Final le arthrology guide table 25

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Arthrology Guide of the Lower Extremity

Kylie Bauman, Jessie Brown, Sivan Fogel, Mariah Granzella, Michael Kaspin, Kelsey Poos-‐Benson, Megan Smith, Allie Stone

Lower Extremity Arthrology

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Table of Contents Hip Joint Complex _________________________________________________________________________________________ 6

Introduction _____________________________________________________________________________________________________ 6 Muscles of the Hip Joint Complex ______________________________________________________________________________ 6

Symphysis Pubis Joint ____________________________________________________________________________________________ 8 Overview ________________________________________________________________________________________________________ 8 Tissue Layers ___________________________________________________________________________________________________ 8 Joint Motion _____________________________________________________________________________________________________ 9 Biomechanics ___________________________________________________________________________________________________ 9 Joint Configuration ____________________________________________________________________________________________ 10 Ligaments of the Symphysis Pubis ___________________________________________________________________________ 10 Common Joint Pathology ______________________________________________________________________________________ 11

Sacroiliac Joint ___________________________________________________________________________________________________ 11 Overview _______________________________________________________________________________________________________ 11 Tissue Layers __________________________________________________________________________________________________ 13 Joint Motions ___________________________________________________________________________________________________ 13 Biomechanics __________________________________________________________________________________________________ 13 Joint Configuration ____________________________________________________________________________________________ 17 Ligaments of the Sacroiliac ___________________________________________________________________________________ 18 Common Joint Pathology ______________________________________________________________________________________ 18

Femoroacetabular Joint _________________________________________________________________________________________ 19 Overview _______________________________________________________________________________________________________ 19 Tissue Layers __________________________________________________________________________________________________ 20 Joint Motions ___________________________________________________________________________________________________ 21 Biomechanics __________________________________________________________________________________________________ 21 Joint Configuration ____________________________________________________________________________________________ 25 Ligaments of the Femoral Acetabular ________________________________________________________________________ 27 Common Joint Pathology ______________________________________________________________________________________ 28

Knee Joint Complex ______________________________________________________________________________________ 30 Introduction ____________________________________________________________________________________________________ 30 Muscles of the Knee Joint Complex ___________________________________________________________________________ 31

Tibiofemoral Joint _______________________________________________________________________________________________ 32 Overview _______________________________________________________________________________________________________ 32 Tissue Layers __________________________________________________________________________________________________ 32 Joint Motions ___________________________________________________________________________________________________ 34 Biomechanics and Joint Configuration _______________________________________________________________________ 34 Ligaments of the Tibiofemoral ________________________________________________________________________________ 37 Common Joint Pathology ______________________________________________________________________________________ 38

Patellofemoral Joint ______________________________________________________________________________________________ 40 Overview _______________________________________________________________________________________________________ 40 Tissue Layers __________________________________________________________________________________________________ 41 Joint Motion ____________________________________________________________________________________________________ 42 Biomechanics __________________________________________________________________________________________________ 42 Ligaments of the Patellofemoral Joint ________________________________________________________________________ 45 Common Joint Pathology ______________________________________________________________________________________ 45

Lower Extremity Arthrology Guide 3

Foot and Ankle Joint Complex __________________________________________________________________________ 48 Overview _______________________________________________________________________________________________________ 48 Muscles of the Ankle Joint Complex __________________________________________________________________________ 49 Muscles of the Foot Joint Complex ___________________________________________________________________________ 50

Proximal Tibiofibular Joint _____________________________________________________________________________________ 51 Overview _______________________________________________________________________________________________________ 51 Tissue Layers __________________________________________________________________________________________________ 52 Joint Motion ____________________________________________________________________________________________________ 53 Biomechanics __________________________________________________________________________________________________ 53 Joint Configuration ____________________________________________________________________________________________ 54 Ligaments of the Proximal Tibiofibular ______________________________________________________________________ 55 Common Pathology ____________________________________________________________________________________________ 55

Distal Tibiofibular joint _________________________________________________________________________________________ 56 Overview _______________________________________________________________________________________________________ 56 Tissue Layers __________________________________________________________________________________________________ 56 Joint Motions ___________________________________________________________________________________________________ 57 Biomechanics and Joint Configuration _______________________________________________________________________ 57 Ligaments of the Distal Tibiofibular __________________________________________________________________________ 58 Common Joint Pathology ______________________________________________________________________________________ 58

The Talocrural Joint _____________________________________________________________________________________________ 59 Overview _______________________________________________________________________________________________________ 59 Tissue Layers __________________________________________________________________________________________________ 59 Joint Motions ___________________________________________________________________________________________________ 60 Biomechanics and Joint Configuration _______________________________________________________________________ 60 Ligaments of the Talocrural __________________________________________________________________________________ 62 Common Joint Pathology ______________________________________________________________________________________ 62

Subtalar Joint ____________________________________________________________________________________________________ 63 Overview _______________________________________________________________________________________________________ 63 Tissue Layers __________________________________________________________________________________________________ 64 Joint Motions ___________________________________________________________________________________________________ 65 Biomechanics __________________________________________________________________________________________________ 65 Joint Configuration ____________________________________________________________________________________________ 66 Ligaments of the Subtalar _____________________________________________________________________________________ 67 Common Joint Pathology ______________________________________________________________________________________ 67

Transverse Tarsal Joint (Calcaneocuboid Joint and Talonavicular joint) __________________________________ 69 Overview _______________________________________________________________________________________________________ 69 Tissue Layers __________________________________________________________________________________________________ 69 Joint Motions ___________________________________________________________________________________________________ 70 Biomechanics __________________________________________________________________________________________________ 70 Joint Configuration ____________________________________________________________________________________________ 72 Ligaments of the Transverse tarsal joint (Calcaneocuboid Joint and Talonavicular joint) ______________ 73 Common Joint Pathology ______________________________________________________________________________________ 73

Cuneonavicular joint (Distal intertarsal joint) ________________________________________________________________ 74 Overview _______________________________________________________________________________________________________ 74 Tissue Layers __________________________________________________________________________________________________ 74 Joint Motions ___________________________________________________________________________________________________ 75


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Biomechanics __________________________________________________________________________________________________ 75 Joint Configuration ____________________________________________________________________________________________ 76 Ligaments of the Cuneonavicular or Distal Intertarsal _____________________________________________________ 77 Common Pathology ____________________________________________________________________________________________ 77

Cuboideonavicular Joint ________________________________________________________________________________________ 78 Overview _______________________________________________________________________________________________________ 78 Tissue Layers __________________________________________________________________________________________________ 78 Joint Motions ___________________________________________________________________________________________________ 79 Biomechanics __________________________________________________________________________________________________ 79 Joint Configuration ____________________________________________________________________________________________ 80 Ligaments of the Cuboideonavicular _________________________________________________________________________ 80 Common Joint Pathology ______________________________________________________________________________________ 80

Intercuneiform and Cuneocuboid Joints _______________________________________________________________________ 80 Overview _______________________________________________________________________________________________________ 80 Tissue Layers __________________________________________________________________________________________________ 81 Joint Motions ___________________________________________________________________________________________________ 82 Biomechanics __________________________________________________________________________________________________ 82 Joint Configuration ____________________________________________________________________________________________ 82 Ligaments of the Intercuneiform and Cuneocuboid ________________________________________________________ 83 Common Joint Pathology ______________________________________________________________________________________ 83

Tarsometatarsal Joints __________________________________________________________________________________________ 84 Overview _______________________________________________________________________________________________________ 84 Tissue Layers __________________________________________________________________________________________________ 85 Joint Motions ___________________________________________________________________________________________________ 86 Biomechanics __________________________________________________________________________________________________ 86 Joint Configuration ____________________________________________________________________________________________ 88 Ligaments of the Tarsometatarsals __________________________________________________________________________ 89 Common Joint Pathology ______________________________________________________________________________________ 90

Intermetatarsal Joints ___________________________________________________________________________________________ 90 Overview _______________________________________________________________________________________________________ 90 Tissue Layers __________________________________________________________________________________________________ 91 Joint Motions ___________________________________________________________________________________________________ 92 Biomechanics __________________________________________________________________________________________________ 92 Joint Configuration ____________________________________________________________________________________________ 93 Ligaments of the Intermetatarsal Joints _____________________________________________________________________ 93 Common Joint Pathology ______________________________________________________________________________________ 93

Metatarsophalangeal Joint (MTP joints) ______________________________________________________________________ 95 Overview _______________________________________________________________________________________________________ 95 Tissue Layers __________________________________________________________________________________________________ 95 Joint Motions ___________________________________________________________________________________________________ 96 Biomechanics __________________________________________________________________________________________________ 96 Joint Configuration ____________________________________________________________________________________________ 97 Ligaments of the Metatarsophalangeal ______________________________________________________________________ 98 Common Joint Pathology ______________________________________________________________________________________ 98

Interphalangeal Joints ___________________________________________________________________________________________ 99 Overview _______________________________________________________________________________________________________ 99


Tissue Layers __________________________________________________________________________________________________ 99 Joint Motions _________________________________________________________________________________________________ 100 Biomechanics ________________________________________________________________________________________________ 100 Joint Configuration __________________________________________________________________________________________ 101 Ligaments of the Interphalangeals _________________________________________________________________________ 101 Common Pathology __________________________________________________________________________________________ 101


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Hip Joint Complex Introduction

The hip joint complex is the critical link between the lower extremity and the trunk. This system must

absorb and transmit enormous forces while also allowing a large arc of motion. The hip joint complex is made up

of four joints: the femoroacetabular joint, the right and left sacroiliac (SI) joints, and the pubic symphysis.

Typically, the femoroacetabular joint is referred to as the hip joint. This is the ball and socket articulation where

most of our lower extremity range of motion comes from. However; the SI joints and the pubic symphysis create

the stable ring of the pelvis and may affect how the hip can function in open and closed kinetic chain. The pelvis

is made up of two innominates created by the ileum, ischium and pubis, which are connected anteriorly at the

symphysis pubis and posterior at the right and left sacroiliac (SI) joints. The innominate bones fuse together

forming the acetabulum where the head of the femur articulates wit the pelvis. The SI joint is an articulation

between the sacrum of the spinal column and the ileum bones of the pelvis. The pubic symphysis is the

articulation between the two pubic bones of the pelvis. The common hip joint complex has three distinct

functions, it acts as attachment site for various muscles and connective tissues, supports the organs such as the

urinary bladder and intestines, and helps transmit weight from the appendicular to axial skeleton.

Muscles of the Hip Joint Complex

Category Muscle Function Origin Insertion Nerve Blood Supply Gluteal Region

Gluteus maximus Hip extensor External rotator (H)

Surface of ilium, sacrum and coccyx

Iliotibial tract and gluteal tuberosity of the femur

Inferior gluteal (L5, S1, S2)

Inf. & Sup. Gluteal

Gluteus medius Hip abductor Internal rotator (H)

Surface of ilium Greater trochanter

Superior gluteal

Superior gluteal

Gluteus minimus Hip abductor Internal rotator (H)

Surface of ilium Greater trochanter

Superior gluteal

Superior gluteal

Tensor Fascia Latae

Med rotation, flexion of the hip. Abduction

Outer surface of ilium

Iliotibial tract Superior gluteal

Superior gluteal

Pelvic Region

Gluteus maximus Hip extensor External rotator (H)

Surface of ilium, sacrum and coccyx

Iliotibial tract and gluteal tuberosity of femur

Inferior gluteal

Inf. & Sup. Gluteal

Piriformis External rotator (H)

Sacrum Greater trochanter

Sacral plexus

Inf. & Sup. Gluteal

Superior gemellus External rotator (H)

Ischial spine Greater trochanter

Sacral plexus

Inf. Gluteal


Inferior gemellus External rotator (H)

Ischial tuberosity Greater trochanter

Sacral plexus

Inf. Gluteal

Obturator internus External rotator (H)

Inner surface of obturator foramen

Greater trochanter

Sacral plexus

Inf. Gluteal

Obturator externus External rotator (H)

Outer surface of obturator foramen

Greater trochanter

Obturator Med. circumflex femoral & Obturator

Anterior Thigh

Pectineus

Hip Flexor Hip Adductor

Pubic ramus Upper medial femur

Femoral Med. Circumflex femoral & Obturator

Sartorius

Hip Flexor Hip Abductor External rotator (H) Knee extensor

Anterior superior iliac spine

Upper medial tibia

Femoral Femoral

Rectus femoris Hip Flexor Hip Extensor External rotator (H)

Upper shaft of femur

Patellar ligament Femoral Lateral circumflex femoral

Vastus medialis Hip Extensor External rotator (H)


Patellar ligament Femoral Femoral

Vastus lateralis Hip Extensor External rotator (H)



Vastus intermedius

Hip Extensor External rotator (H)



Category Muscle Function Origin Insertion Nerve Blood Supply Medial Thigh

Gracilis

Knee Flexor Hip Adductor

Pubic ramus Upper medial tibia

Obturator Med circumflex femoral & obturator

Adductor magnus Hip Adductor External rotator (H)

Pubic ramus Posterior surface of shaft of femur


Adductor brevis Hip Adductor External rotator (H)



Adductor Longus Hip Adductor External rotator (H)



Posterior Thigh

Semitendinosus Hip Extensor Knee Flexor

Ischial tuberosity Medial condyle of tibia

Tibial Perforating br. Of deep femoral

Semimembranosus Hip Extensor Knee Flexor

Ischial tuberosity Medial condyle of tibia


Long head of biceps femoris

Hip Extensor Knee Flexor External rotator (H)

Ischial tuberosity Fibular head Tibial Perforating br. Of deep femoral

Short head of biceps femoris

Knee Flexor External rotator (H)

Lateral shaft of femur

Fibular head Fibular Perforating br. Of deep femoral

Hamstring part of adductor magnus

Hip Extensor

Ischial Tuberosity Medial shaft of femur (adductor tubercle)



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Symphysis Pubis Joint

Overview

The symphysis pubis joint primarily acts as a stabilizer to allow some mobility in the pelvic ring without

compromising stability of the lower extremity and trunk. It is a

synarthrosis fibrocartilaginous joint, joined together by a fibrocartilaginous

disc; called the interpubic disc. The interpubic disc is situated between two

layers of hyaline cartilage that line the medial articular surfaces of the two

pubic bones. The joint is further reinforced by a series of ligaments and

tendinous sheaths that stabilize the symphysis pubis and prevent excessive

separation, compression, shift, or rotation from occurring.

The symphysis pubis helps to disperse force transmitted from the lower extremity up through the pelvic

ring to the axial skeleton during gait and impact activity. It is not commonly injured, but joint laxity during

pregnancy and postpartum can result in pelvic dysfunction and symphysis pubis pain. As it is not a synovial joint,

no joint capsule exists and instead the joint articulates via the interpubic disc. This joint does not act in

physiological kinematics and arthrokinematics beyond a few degrees of shift or rotation are indicative of

dysfunction and may lead to pain. Even so, the symphysis pubis is key to allowing pelvic ring pliability during

childbirth while maintaining a stable structure for large force distribution in everyday activity.

Tissue Layers • Skin

o Epidermis o Dermis o Hypodermis

• Subcutaneous tissue o Camper’s Fascia o Scarpa’s Fascia

• Rectus Abdominis Sheath o External Oblique mm. and aponeurosis o Internal Oblique mm. and aponeurosis o Transversus Abdominis mm. and aponeurosis o Rectus abdominis mm. o Transversalis Fascia

Figure 1 Interpubic disc


• Tendons o Adductor Brevis o Adductor Longus o Pectineus o Gracilis o Adductor magnus o Quadratus o Obturator externus

• Neurovasculature o Obturator aa. and vv. o Inferior epigastric aa. and vv. o Pudendal nn. o Genital branch of genitofemoral nn. o Iliohypogastric/ilioinguinal nn.

• Ligaments o Superior pubic ligament o Anterior pubic ligament o Inferior pubic (arcuate) ligament o Posterior pubic ligament o Inguinal Ligament

• Bones o Pubic Bones

• Interpubic disc

Joint Motion Joint Motion* Primary Movers Secondary Movers

2mm Shift (inferior/superior) Gravity, ground reaction force through LE Adductor brevis, longus, gracilis, rectus abdominis, external oblique aponeurosis

N/A

1° Rotation Same* N/A *Due to the stability of the pubic symphysis, no muscles act directly on it. Rather, gravity and ground reaction forces indirectly shift and rotate its approximation as well as conjunct movement of muscles that attach here.

Biomechanics

The two pubic bones have medial hyaline cartilage-covered articulating surfaces. They articulate at

midline as reinforced by many ligaments and fibrocartilage connections. The articulating surfaces contain small

ridges to increase stability and resist shear forces. The interpubic

disc lies in between the joint surfaces providing a binding surface.

The joint is primarily subject to compression forces at its superior

border and tensile forces at its inferior border with everyday

activity of sitting and walking; especially during single limb

stance due to activity of the rectus sheath superiorly and the Figure 2 Muscular reinforcement of pubic symphysis


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adductor tendons inferiorly as Figure 2 illustrates. The joint allows up to 2mm of translation in the sagittal plane

and 1° of rotation. The average displacement of the pubic bones in any direction (most prominently during single

limb stance) is 1-2mm higher in women who have bore children compared to both men and nulliparous women.

The joint is strongly reinforced via four ligamentous structures. According to Ibrahim & El-Sherbini in 1961, the

ligaments from strongest to weakest were anterior: inferior: superior; with no data provided on the posterior pubic

ligament. The strength of these ligaments were strongest in men, then nulliparous women, then women who had

children, and weakest in women during their third trimester of pregnancy.

Joint Configuration

According to Becker et al. the most current anatomical and arthrodial evidence reported on the symphysis

pubis is from 1990. In Becker et al.’s 2010 systematic review, they concluded that the articular surfaces of the

pubic bones are slightly convex, oval shaped and running posteroinferiorly in a craniocaudal direction.

Posteriorly the surfaces are parallel but separate anterior and superiorly. The subchondral bone begins rough and

uneven in childhood, but is relatively smooth by 30 years of age. As degenerative changes occur in late adulthood,

the subchondral bone surface roughens again by age 60.

Ligaments of the Symphysis Pubis

Ligament Attachments Function Other constraints Superior Pubic Ligament Bilateral pubic crests as far laterally as pubic

tubercles, interpubic disc, pectineal ligament, linea alba

Controversial but most likely reinforcement of superior portion of joint

Stability

Inferior Pubic Ligament (subpubic, arcuate)

Inferior pubic rami bilaterally, interpubic disc Reinforce inferior portion of joint

Stability

Anterior Pubic Ligament Anterior pereosteum of pubic bones bilaterally. Interpubic disc

Reinforce anterior symphysis pubis

Strongest ligament of symphysis pubis.

Posterior pubic ligament A few thin fibers spanning posterior symphysis pubis, blending with pubic rami pereosteum and superior and inferior pubic ligaments.

Reinforce symphysis pubis joint

Stability

Interpubic Disc (fibrocartilaginous)

Medial articular surfaces of bilateral pubic bones, fused with superior, inferior, anterior, posterior pubic ligaments

Withstand compressive and tensile stresses

Stability, maintain pelvic ring integrity

Figure 3 Bony features of symphysis pubis


Common Joint Pathology

Parturition-Induced Pelvic Instability. The symphysis pubis is relatively immobile and so most

pathologies related to its anatomy are due to excessive mobility. The most common pathology of the symphysis

itself is parturition-induced pelvic instability. This is excessive mobility and pain of the symphysis pubis due to

increases in relaxin and progesterone hormones during and after childbirth in women. The symphysis can widen

in women after childbirth 3-7mm and is treated conservatively with a brace to promote compression of the

symphysis, muscular strengthening to increase dynamic stability and modified activity.

Pelvic Fracture. In addition to childbirth, acute trauma can cause mass instability of the symphysis pubis.

An open book pelvic fracture is a fracture to the pelvic ring induced from an anterior to posterior compression

force. This causes the symphysis pubis to separate and open the pelvis up like a book. This fracture is often

accompanied by sacroiliac joint pain and pathology. This is a devastating injury necessitating surgery to repair

arteries and manage blood loss as well as reapproximate the symphysis pubis.

Osteitis Pubis. An additional common pathology of the symphysis pubis is osteitis pubis. This is

inflammation of the symphysis pubis due to a variety of irritants. The most common causes of osteitis pubis are

high level of athletic activity disrupting adductor tendon attachments to the pubis, childbirth disruption of the

joint, or secondary effects of urologic or gynecologic surgery.

Sacroiliac Joint

Overview

Sacroiliac (SI) joint is the articulation between the ilium and the sacrum. This joint is designed for

stability and transfer of either light loads or heavy loads. These loads are

transferred through vertebral column, lower extremities, and the ground.

The SI joint is made up of the articulation of the sacrum with the

ilium on each side. The articular surfaces are ear shaped, containing

irregular ridges and depressions. The concave sacral surface is Figure 4 Sacroiliac bony structure


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covered with thick hyaline cartilage and the convex iliac surface is lined with thin fibrocartilage. The joint

is comprised of strong and dense ligamentous structures that contribute to the SI joint being one of the

most stable joints in the body. Numerous muscles also attach to the SI joint that assist in stabilizing the

joint.

The SI joint configuration undergoes changes during aging that are related to dysfunction. In

adolescence the SI joint is mostly synovial with smooth articular surfaces. This smooth surface of the joint

in early childhood permits gliding motions in all directions. Through puberty and entering adulthood, the joint

characteristics change. The joint becomes part syndesmosis and part synovial. The articular surfaces also

change from smooth to more rough and irregular between puberty and adulthood. The irregular and rough

surface changes happen on both the articular surfaces and the subchondral bone. The joint also becomes

less mobile through the aging process. The ligaments that cover the joint become more fibrotic and less

elastic. The hyaline cartilage that covers the concave sacral surface thins and may cause adhesions to occur

between the sacrum and the ilium. Due to these changes, motion (primarily rotation) becomes minimal and

the joint becomes more mature and stable.

Anatomical features of the joint also differ with gender. The female sacrum is shorter, wider, and

more posteriorly curved than the male sacrum to provide more room for the passage of the newborn through the

birth canal during childbirth. The male sacrum is long, narrow, straighter, and has a more pronounced sacral

promontory. These differences are due to greater imposed forces on the joint in males compared to females

according to Vleeming et al. The sacroiliac ligaments in women are more elastic than men’s, allowing the

mobility necessary for childbirth.

Neurovasculature. Blood supply to the joint is derived from iliolumbar, superior gluteal, and lateral

sacral arteries. The sacroiliac joint is also well innervated. According to Forst SL; histological analysis of the

sacroiliac joint has verified the presence of nerve fibers within the joint capsule and adjoining ligaments. It has

been variously described that the sacroiliac joint receives its innervations from the ventral rami of L4 and L5, the

superior gluteal nerve, and the dorsal rami of L5, S1, and S2.


Tissue Layers • Integumentary


• Superficial fascia o Subcutaneous tissue o Stored fat o Loose connective tissue o Neurovasculature

• Muscles/Fascia o Thoracolumbar fascia

§ Posterior layer § Lateral raphe § Middle layer § Anterior Layer

o Erector Spinae § Iliocostalis § Longissimus

o Gluteus maximus o Gluteus medius o Gluteus minimus o Piriformis o Iliacus o Psoas Major

• Ligaments • Joint articular surfaces

Joint Motions

Joint Motion* Associated Muscles

Stability Biceps femoris, Gluteus maximus, Latissimus dorsi, Iliacus, Piriformis Erector spinae, Lumbar multifidi, Rectus abdominis, Internal abdominal obliques, Transversus abdominis

Nutation Biceps femoris, Erector spinae, Rectus abdominis Counternutation Rectus femoris, Tensor fascia latae, Adductor longus, Pectineus * It should be noted that movement at the SI joint occurs secondarily due to movement of the innominate bones. No muscle directly acts on the SI joint.

Biomechanics

The articular surface of the ilium is convex and the articular surface of the sacrum is slightly concave.

The SI joint permits a small amount of motion that varies among individuals. The smooth SI joint surfaces in

early childhood permit gliding motions in all directions, which is typical of a synovial plane joint. However, after

puberty, the joint surfaces change their configuration and motion in the adult is restricted to a few millimeters.

Due to the congruency of the joint, movement is described as the concave sacrum moving on the convex ilium.


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When the movement does occur at the ilium, the movement that describes the movement at the sacrum is

described as nutation and counternutation.

These motions occur around its mediolateral

axis at the level of S2 and are limited to the

near sagittal plane. Nutation occurs as the

sacrum moves anteriorly and inferiorly while

the coccyx moves posteriorly relative to the ilium.

Nutation occurs with a posterior iliac tilt. Counternutation is simply the opposite and occurs when the sacrum

moves posteriorly and superiorly while the coccyx moves anteriorly relative to the ilium. Counternutation occurs

with anterior pelvic tilt. Ilium-on-sacral rotation, sacral-on ilium rotation, or complimentary motion of both can

accomplish nutation and counternutation. These motions help transfer the forces between the axial skeleton and

lower extremities.

During gait, the SI joint is very important as it is the location for force transmission from the trunk to the

ground and from the ground to the trunk. In order for the forces to be transferred efficiently the joint has to be

stable. Stability of the joint comes from strong, fibrous ligaments, the irregular articular surfaces of the ilium and

sacrum, and muscular stabilizers. Stability of the SIJs is extremely important because these joints must support a

large portion of the body weight. In normal erect posture, the weight of head, arms, and trunk (HAT) is

transmitted through the fifth lumbar vertebra and lumbosacral disk to the first sacral segment. The joint must

support significantly more than the weight of the body if an individual is lifting or carrying weighted objects

As noted earlier the SI joint is very stable joint with minimal movement. The movement that does occur

at the joint is very important for stress relief during walking, running, and during childbirth in women. During

walking, the pelvis rotates from side to side as the lower extremity changes from a position of flexion to

extension. In normal gait with typical speed, the heel of advancing lower limb strikes the ground as the toes of the

opposite limb are still in contact with the support. It is this point in gait that the ligaments and muscles at the hips

create oppositely directed torsions on the right and left iliac crests. Torsions are most notable in sagittal and

Figure 5 Nutation and Counternutation of SI joint


horizontal plane. If the SI joint was a solid and continues structure, the SI joint would not be able to dissipate

damaging stress and the pelvic ring would be damaged with everyday activity.

Gravity is the first line of stability for the SI joint. In an upright position the bodies center of mass is just

anterior to S2, which is the midpoint between an imaginary line connecting the two SI joints The downward force

of gravity that is a result from the body weight passing through the vertebra forces the trunk downwards on the

sacrum while the joint transfers weight from the lower extremity to the spine. This creates a nutation moment

about the joint. At the same time, ground reaction forces act on the femoral head, causing an upward directed

compression force through the acetabulum. This forces the ilium to rotate posteriorly. The nutation moment

created by gravity and the ground reaction force causing the ilium to rotate posteriorly creates a locking

mechanism. This locking mechanism relies primarily on gravity and congruity of the joint surfaces rather than the

extra-articular structures such as ligaments and muscles.

Ligaments also provide stability to the joint as the ligaments

of the sacrum are some of the strongest and toughest ligaments in the

body that are difficult to tear, stretch, and mobilize. The primary

stabilizing ligaments of the SI joint are the interosseous sacroiliac,

anterior sacroiliac, iliolumbar, and posterior sacroiliac ligaments as

illustrated in Figure 6 and 7. The secondary ligaments that stabilize

the sacrum are the sacrotuberous and sacrospinous ligaments.

The interosseous sacroiliac ligament strongly and rigidly

binds the sacrum with the ilium. The major function of the

interosseous sacroiliac ligament is to prevent abduction or distraction

of the sacroiliac joint. It is also the interosseous sacroiliac ligaments

that are responsible for transferring the weight from the axial

skeleton to the appendicular skeleton. The anterior sacroiliac

Figure 7 Ligaments of Posterior Sacrum

Figure 6 Ligaments of Anterior Sacrum


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ligaments are thin anterior parts of the fibrous capsule of the synovial part of the joint. Iliolumbar ligaments blend

in with the anterior sacrospinous ligaments and radiate from transverse processes of L5 vertebra to the ilia.

Posterior sacroiliac ligaments connect the PSIS with the lateral crests of the third and fourth segments of the

sacrum and are very strong and tough. The short band of the posterior sacroiliac ligament also provides stability

against all movements. Due to the posterior sacroiliac and interosseous sacroiliac ligaments running obliquely

upward and outward from the sacrum, the axial weight pushing downward on the sacrum forces the ilia medially.

This causes the sacrum to be compressed between the ilia and locks the irregular but congruent surfaces of the

sacroiliac joints together. Iliolumbar ligaments act as accessory ligaments and assist in this mechanism.

Sacrotuberous and sacrospinous ligaments offer secondary support posteriorly. They do not actually cross the

joint, but they indirectly assist stabilization by resisting nutation.

Stability is adequate for activities that involve relatively low static loading such as sitting and standing.

For larger more dynamic loading, the SI joint is reinforced by ligaments and muscles. Nutation torque stretches

many of the connective tissues at the SI joint. Increased tension in these ligaments further compresses the surface

of the SI joint and thereby adds to their transarticular stability.

In addition to ligaments, several hip and trunk muscles reinforce and stabilize the sacroiliac joints. Such

muscles are erector spinae, lumbar multifidi, rectus abdominis, obliques abdominis internus and externus,

transversus abdominis, gluteus maximus, latissimus dorsi, iliacus and piriformis. These muscles stabilize the SI

joint by (1) generating active compressive forces against the articular surfaces, (2) increasing magnitude of

nutation torque and subsequently engaging the active locking mechanism, and (3) pulling on connective tissues

that reinforce the joints. As an example, let's consider erector spinae and bicep femoris. Erector spinae muscle

will rotate the sacrum anteriorly and biceps femoris will rotate the ileum posteriorly and thus both of these actions

create nutation. It is then safe to assume that anterior tilt of the pelvis will create counternutation. The muscles

that create anterior tilt at the pelvis could create counternutation at the sacrum. Some of these muscles include

iliopsoas, rectus femoris, tensor fascia latae, adductor longus, and pectineus.


Mechanical stability of the SI joint is provided by thoracolumbar fascia. Thoracolumbar fascia consists of

three different layers that surround the posterior muscles of the lower back. Those layers are anterior, middle, and

posterior. The anterior and middle layers are anchored medially to the transverse processes of the lumbar

vertebrae and inferiorly to the iliac crest. The posterior layer covers the posterior surface of the erector spinae and

latissimus dorsi muscle. The posterior layer attaches to the spinous processes of lumbar vertebrae, the sacrum, and

the ilium, adding stability to the SI joint. Posterior layer stability to the joint is provided by erector spinae muscle

creating a nutation torque by rotating the sacrum anteriorly and thus locking the joint and stabilizing it. Medial

and posterior layers of thoracolumbar fascia fuse at their lateral margins and thus blend with internal oblique and

transversus abdominis musculature. The internal oblique and transversus abdominis muscles compress the ilia

toward the sacrum, increasing joint stability. Stability is further enhanced by the superficial attachments of

latissimus dorsi and gluteus maximus to thoracolumbar fascia resulting in an increased compression of the SI

joint. The iliacus and piriformis muscles provide secondary stability at the SIJ articulation by attaching directly to

the capsule or margins of the SI joint.

Pregnancy plays a large role in SI joint biomechanics in women. The release of relaxin during pregnancy

decreases the intrinsic strength and rigidity of collagen. The action of relaxin is responsible for the softening of

the ligaments supporting the SI joint and the symphysis pubis. This causes the joint to become more mobile, less

stable and increase the size of pelvic outlet during childbirth. There is less resistance to these hormonal-induced

changes due to the smoother articular surfaces of the SI joints of women being pregnant.

Joint Configuration

The SI joint is the articulation between the auricular surface of the sacrum and the ilium. SI joint is

formed within sacral segments S1, S2 and S3. As mentioned previously the articular surface of the ilium is

convex and faces anteriorly and inferiorly. The articulating surface of the sacrum is concave and faces more

posterior and inferiorly compared to the ilium. The articulating surfaces on the sacrum are C-shaped and are

located on the sides of the fused sacral vertebrae lateral to the sacral foramina. The SI joint consists of an anterior

synovial joint and a posterior syndesmosis. The articular surfaces of this synovial joint have irregular but


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congruent elevations and depressions that interlock. The articulating surface of the sacrum is covered by hyaline

cartilage. The ilium-articulating surface is covered by fibrocartilage. The overall mean thickness of the sacral

cartilage is greater than that of the iliac cartilage.

Ligaments of the Sacroiliac

Ligaments Attachments Function Associated Constraints

Anterior Sacroiliac

3rd sacral segment to the lateral side of the pre-auricular sulcus

Primary source of stability; reinforce the anterior side of the SI joint

Nutation

Iliolumbar Tip and anteroinferior aspect of the transverse process of L5 to (1) the posterior margin of the iliac fossa and (2) to the iliac crest anterior to the sacroiliac joint

Primary source of stability; reinforce the anterior side of the SI joint; stabilizes L5 on the ilium

Nutation

Interosseous Sacroiliac

Deep portion: superior and inferior bands from depressions posterior to the sacral auricular surface to those on the iliac tuberosity Superficial: sheet connecting the poster superior margin posterior to the sacral auricular surface to the corresponding margins of the iliac tuberosity

Forms part of the sacroiliac articulation (syndesmosis): binds the sacrum to the ilium; Primary source of stability

Stability in all motions

Posterior sacroiliac (short and long)

Short: posterior- lateral side of the sacrum to the ilium, near the iliac tuberosity and the PSIS Long: 3rd and 4th sacral segments to PSIS

Primary source of stability; reinforce the posterior side of the SI joint

Short: all pelvic and sacral movement Long: Counternutation

Sacrotuberous Posterior superior iliac spine (PSIS), lateral sacrum, and coccyx, attaching to the ischial tuberosity

Secondary source of stability Nutation

Sacrospinous Lateral margin of caudal end of sacrum and coccyx, attaching to the ischial spine

Secondary source of stability Nutation


Osteoarthritis. As with most other joints in the body, the SI joints have a cartilage layer covering the

bone. When this cartilage is damaged or worn away osteoarthritis may occur. This could cause severe pain and

discomfort for the patient. As the condition progresses at the SI joint, the joint cleft narrows and osteophytes may

form within the ligaments. These osteophytes could ossify the ligaments and fuse the sacrum to the ilium and

cause complete immobilization of the SI joint.

Parturition-Induced SIJ Pain. Laxity of the sacroiliac joint could also cause symptomology. Women

are more likely to experience this than men because of childbearing. During childbirth, release of relaxin and

progesterone cause more mobility and an increase in synovial fluid. Hypermobility and ligament laxity could

cause increased risk of injury such as dislocation and pelvic girdle pain postpartum.


Ankylosing spondylitis. Ankylosing spondylitis is an inflammatory condition of the joints, especially in

the spinal column. Inflammation within joints can lead to severe pain and discomfort. In very severe cases the

inflammation can induce fibrosis and cause the bones to fuse, resulting in massive restrictions to mobility. Typical

patient complaints are persistent low back pain and stiffness that is worse in the morning and night, but improves

with activity. Patients often complain of unilateral or alternating buttock pain. Also, patients tend to complain of

pain during the second half of sleep only. Differential diagnosis for ankylosing spondylitis include stress fracture,

muscle spasm, lumbar disk herniation, osteoarthritis, gout, cancer, infection, and rheumatoid arthritis. The disease

most commonly presents in young males, ages 15-30 years old.

Femoroacetabular Joint

Overview

The femoroacetabular (FA) joint, more commonly known as the hip joint is a ball and socket joint and is

created with an articulation between the femoral head and the socket of the

acetabulum on the pelvis with three degrees of freedom. Three bones of the pelvis;

the ischium, ilium, and pubis form the acetabulum. The femur is the longest and

strongest bone in the body. The femoral head projects medially and slightly

anteriorly for an articulation with the acetabulum. The femoral head is secured

within the acetabulum by an extensive set of connective tissues and muscles. Thick

layers of articular cartilage, muscle, and cancellous bone in the proximal femur help reduce the large forces that

cross the joint. The hip is required to operate in both open and close kinetic chain and so stability is very

important at this joint. The stability to the joint mostly comes from the joint configuration as well as the

ligamentous design. Muscles also contribute to joint stability as the joint must

withstand high loads during activity such as running, jumping, and walking.

Neurovasculature. The femoroacetabular joint receives its blood supply

from the artery to the head of the femur, but the primary blood supply to the joint

Figure 8 Femoroacetabular Joint Surfaces

Figure 9 Bones of Acetabulum


20

comes from the medial and lateral circumflex femoral arteries, which come off the deep femoral artery. The joint

is also highly innervated as the sacral and lumbar plexus are close in proximity to it and provide numerous

innervating branches. The joint gets innervations from femoral nerve (anteriorly), obturator nerve (inferiorly),

nerve to quadratus femoris (posterior), and the superior gluteal nerve (superior).



• Subcutaneous tissue o Fascia lata o Subcutaneous adipose tissue

• Muscle o Anterior compartment

§ Pectineus § Iliopsoas § Rectus femoris § Sartorius

o Medial compartment § Adductor longus § Adductor brevis § Adductor magnus § Gracilis § Obturator externus

o Posterior compartment § Semitendinosus § Semimembranosus § Biceps femoris (long head)

o Gluteal region § Gluteus maximus § Gluteus medius § Gluteus minimus § Tensor fasciae latae § Piriformis § Obturator internus § Superior gemellus § Inferior gemellus § Quadratus femoris

• Ligaments and joint capsule • Joint articular surfaces and deep ligaments


Joint Motions

Biomechanics

Since the hip is a ball and socket joint, it is capable of a variety of motions in different planes. The

femoral head is convex and the acetabular socket is concave. The hip joint is capable of working in both open

chain and closed chain positions. In open chain, the femur tends to move on the pelvis in order to create motion.

Since the femur is moving on the pelvis, the convex is moving on the concave, the roll and glide of the femoral

head are in opposite directions. The hip has 120 degrees of flexion in the sagittal plane when the femur spins

around the mediolateral axis. In the frontal plane of open chain movement, the hip has about 40 degrees of

abduction and 25 degrees beyond the neutral line of adduction around the anteroposterior axis. The femur will roll

superior and glide inferior for abduction

and will roll inferior and glide superior for

adduction. In the sagittal plane, the hip also

has 20 degrees of extension with the femur

spinning around the mediolateral axis.

Finally, in the transverse plane, the femur

Joint Motion

Primary Movers Secondary Movers

Flexion Iliopsoas, Sartorius, Tensor fasciae latae, Rectus femoris, Adductor longus, Pectineus

Adductor brevis, Gracilis, Gluteus minimus (anterior fibers)

Extension Gluteus maximus, Biceps femoris (long head), Semitendinosus, Semimembranosus, Adductor magnus (posterior head)

Gluteus medius (posterior fibers), Adductor magnus (anterior head)

Abduction Gluteus medius, Gluteus minimus, Tensor fasciae latae Piriformis, Sartorius

Adduction Pectineus, Adductor longus, Gracilis, Adductor brevis, Adductor magnus

Biceps femoris (long head), Gluteus maximus (lower fibers), Quadratus femoris

Internal rotation

NA Gluteus minimus (anterior fibers), Gluteus medius (anterior fibers), Tensor fasciae latae, Adductor longus, Adductor brevis, Pectineus

External rotation

Gluteus maximus, Piriformis, Obturator internus, Superior gemellus, Inferior gemellus, Quadratus femoris

Gluteus medius (posterior fibers), Gluteus minimus (posterior fibers), Obturator externus, Sartorius, Biceps femoris (long head)

Figure 10 Muscle Actions at Sacroiliac Joint


22

can rotate internally about 35 degrees and externally about 45 degrees around the long axis of the femur. During

external rotation, the femoral head rolls posteriorly and glides anteriorly and during internal rotation the femoral

head rolls anterior and glides posterior. In closed chain, the arthrokinematics flip as the roll and glide of the

acetabulum on the femur are in the same direction because the concave surface is moving on the convex surface.

The pelvis may also move in all three planes around all three axes, although the motions have different

names, and there is a smaller range available. In the frontal plane in closed chain, the pelvis can abduct away from

the femur about 30 degrees and adduct toward the femur about 20 degrees from neutral around the anteroposterior

axis. In closed chain, a superior roll and glide creates abduction, while an inferior roll and glide creates adduction.

In the sagittal plane, the pelvis is capable of anteriorly tilting 30 degrees, and posteriorly tilting 15 degrees by

spinning around the mediolateral axis. Finally, in the horizontal plane, the pelvis can internally and externally

rotate about 15 degrees in each direction, with a total arc of 30 degrees of motion around the transverse axis.

During internal rotation, the acetabulum must anteriorly roll and glide. The opposite is true to create external

rotation

The FA joint has very complex biomechanics. Motion that occurs at the hip joint occurs either in open

chain or in closed chain. In open chain the femur moves on the acetabulum, but in closed chain the acetabulum

moves on the femur. Let's take hip flexion for example, we can take our thigh into flexion while keeping the

pelvis stable, this constitutes as open chain. Closed chain hip flexion would occur when the trunk moves into

flexion while keeping the lower limb stable. When considering movement done on a stable pelvis, we must

consider lumbopelvic rhythm due to the close relationship between the hip and the lumbar spine. The movement

that occurs is in the sagittal plane and is considered to be either ipsidirectional lumbopelvic rhythm or

contradirectional rhythm. Ipsidirectional lumbopelvic rhythm describes a movement in which the lumbar spine

and pelvis rotate in the same direction amplifying overall trunk motion. An example of this motion would be

reaching down to pick something from the ground. Contradirectional rhythm describes a movement in which the

lumbar spine and pelvis rotate in opposite direction. This type of movement is important as it allows for

separation of the pelvis and lumbar spine during activities where the head and neck need to maintain neutral


position. Other motions that occur in closed chain are anterior and posterior pelvic movements. Pelvic tilting is

defined based on the position of the anterior superior iliac spine (ASIS) of the pelvis. When the ASIS moves

anterior and inferior, it is considered an anterior pelvic tilt and results in hip flexion. When the ASIS moves

posterior and superior, it is considered a posterior pelvic tilt and results in hip extension.

Since the hip is a ball and socket joint there is three degrees of freedom and thus mobility will be

influenced by muscular activation. We will first discuss hip flexion of the joint. Iliopsoas, sartorius, tensor fascia

latae, rectus femoris, adductor longus, and pectineus are all considered to be primary hip flexors in an open chain

position. The main hip flexor muscles out of these would have to be iliopsoas due to its large size, line of pull,

and cross-sectional area. The iliopsoas tendon averts posteriorly to its distal attachment. In full hip extension, this

increases the tendon's angle of insertion creating an optimal line of pull. The secondary hip flexors (adductor

brevis, gracilis, and the anterior fibers of gluteus minimus) do not have direct lines of pull into hip flexion, but

they can produce some force in that direction. Additionally, any muscle that is considered a hip flexor in the open

chain position can also produce an anterior pelvic tilt in closed chain. An anterior pelvic tilt is also achieved by

force coupling that occurs between the hip flexors and back extensors on a fixed femur.

In the open chain position, gluteus maximus, the hamstrings (biceps femoris (long head), semitendinosus,

and semimembranosus), and the posterior head of the adductor magnus are considered to be primary hip

extensors. Gluteus maximus is considered to be the primary hip extensor due to its large cross sectional area, line

of pull, and moment arm. Adductor magnus (posterior part) is also considered to be a primary mover due to its

large moment arm. It is at 70 degrees at hip flexion and beyond that most adductors (exception to pectineus) are

capable of assisting with hip extension. The hamstring group is also primary mover due to the line of pull and

large moment arm. All three of those muscles are considered to be the primary movers for hip extension. The

posterior fibers of the gluteus medius and the anterior head of the adductor magnus are secondary movers into hip

extension. Neither one of these muscles has a great line of pull into extension from the anatomical position.

Additionally, the posterior fibers of gluteus medius do not have as much cross sectional area as the other hip

extensor muscles. Similar to the hip flexors, the hip extensors in open chain are all capable of producing a


24

posterior pelvic tilt in closed chain. A force couple between the abdominal muscles and the hip extensors creates

this motion. Additionally, the hip extensors are responsible for eccentrically controlling a forward lean of the

body. The primary extensor muscle group that is responsible for this is the hamstrings. As the body leans forward

the displacement of body weight moves farther in front of the hips requiring a greater activation from the

hamstrings. This is because the moment arm of the gluteus maximus is decreased as the hip flexes, but the

moment arm of the hamstrings is increased.

The primary movers into hip adduction are pectineus, adductor longus, gracilis, adductor brevis, and

adductor magnus. The adductors also are able to work in all three planes; not just the frontal plane. This largely

has to do with their distal attachment not being located precisely in midline. The biceps femoris (long head),

gluteus maximus (lower fibers), and quadratus femoris are all considered to be secondary movers into adduction

because some of their fibers have a line of pull in this direction so they can produce some amount of force into

adduction. Adductors also assist in internal rotation of the hip joint.

The primary hip abductors are the gluteus medius, gluteus minimus, and tensor fasciae latae. The

secondary abductors of the hip joint are considered to be the piriformis and sartorius. Gluteus medius is

considered the main hip abductor. The distal attachment of gluteus medius causes it to have the largest moment

arm of all the other abductors. Gluteus medius also has the largest cross sectional area out of all the other

abductors making it the primary mover in abduction. Gluteus minimus occupies 20% of the total abductor

moment. Tensor fasciae latae occupies 11% of total abductor moment. The hip abductors also contribute to hip

internal rotation. The abductor torque produced by the hip abductor muscles is essential to the control of the

frontal plane pelvic-on-femoral kinematics during walking. During the

stance phase the hip is stabilized over the relative fixed femur by the hip

abductors. The hip abductors also play a crucial role during the single-limb

support phase of gait. Without adequate torque on the stance limb, the

pelvis and the trunk may drop toward the side of the swinging limb. The Figure 11 Trendelenburg Sign


observation of a contralateral hip drop during gait is known as a Trendelenburg gait pattern, and is due to lack of

strength or control of the abductor muscles.

External rotation of the hip is done by gluteus maximus, piriformis, obturator internus, superior gemellus,

inferior gemellus, and quadratus femoris. Gluteus maximus has the largest cross-sectional area and so is

considered the primary external rotator of the hip. The others have fairly small cross-sectional areas but have a

direct line of pull and they provide stability to the posterior aspect of the joint. The gluteus medius (posterior

fibers), gluteus minimus (posterior fibers), obturator externus, sartorius, and biceps femoris (long head) are all

secondary movers into external rotation, due to their indirect lines of pull. Hip external rotators are most

functional during closed chain movements such as cutting, pivoting, and changing direction very rapidly. The

external rotators can also function in open chain movements. Open chain external rotation of the hip will rotate

the foot so the toes point more laterally and the heel is more medial.

The last motion produced by the hip is internal rotation. There are no primary internal rotators of the hip.

This is due to the need of muscles to be oriented in a horizontal plane of motion during standing and that does not

occur. There are many secondary hip internal rotators, though. Secondary movers are gluteus minimus (anterior

fibers), gluteus medius (anterior fibers), tensor fasciae latae, adductor longus, adductor brevis, and pectineus. As

the hip moves from 0 degrees to 90 degrees of flexion, the line of pull and moment arm of many of these muscles

becomes more optimally oriented to create internal rotation at the hip. As the hip moves into 90 degrees of

flexion, some external rotators change their action and assist with internal rotation.

Joint Configuration

During weight bearing the hip must translate immense loads; its closed kinetic chain kinematics help it

provide stability. To promote congruency and stability the acetabular socket of the hip joint is fairly deep. The

acetabular labrum also helps promote stability as it deepens the socket of the joint by an additional 30%. The

labrum also forms a seal around the joint to maintain negative intra-articular pressure and thus create suction that

prevents distraction of the joint. The seal also holds the synovial fluid within the joint and enhances the


26

lubrication of the joint and its ability to dissipate load. The acetabulum and the femoral head also have thick

layers of articular cartilage to prevent wear and tear of the joint surfaces.

The bony anatomy of the hip is somewhat variable and may affect how the

joint can function. Two measurements of the femur are considered: the angle of

inclination and femoral torsion. The angle of inclination occurs in the frontal plane

between an axis through the femoral head and neck and the longitudinal axis of the

femoral shaft. At birth, the angle of inclination is about 140 to 150 degrees. Due to loading across the femoral

neck, the angle reduces to 125 degrees near adulthood. When the angle of inclination varies greatly from typical,

it is referred to either as coxa vara or coxa valga. When the angle is less than 125 degrees it is described as coxa

vara and can lead to genu valgum at the knee. An angle greater than 125 degrees is considered to be coxa valga

and can lead to genu varum at the knee. These varying conditions of the angle of inclination are illustrated in

Figure 12. Femoral torsion occurs in the transverse plane between an axis through the femoral head and neck and

an axis through the distal femoral condyles. At birth, the healthy infant is born with about 40 degrees of femoral

torsion. By age 16 this angle decreases due to bone growth, muscular activity, and weight bearing. Typically, the

femoral head sits 15 degrees anterior to the mediolateral axis, running through the femoral condyles. This is

known as normal anteversion. Any rotation greater than 15 degrees

anterior to the mediolateral axis is described as excessive

anteversion, and is associated with in toeing at the foot.

Conversely, an femoral torsion less than 15 degrees is described as

retroversion and is associated with toe-out at the foot.

Measurements at the acetabulum should also be noted. There are

two commonly used measurements to describe the extent to which the acetabulum covers and secures the femoral

head: center-edge angle and acetabular anteversion angle. The center-edge angle describes the position of the

acetabulum and the amount of coverage it provides over the femoral head. A normal center-edge angle is

approximately 35 degrees. Any significant decrease in this angle will decrease the coverage of the femoral head,

Figure 13 Angle of Inclination

Figure 12 Femoral Torsion


and therefore predispose the hip to dislocations. The acetabular anteversion angle measures the extent to which

the acetabulum projects anteriorly in relation to the pelvis. Normally, acetabular anteversion is about 20 degrees.

When a hip demonstrates excessive acetabular anteversion, the anterior portion of the femoral head is exposed.

When the angle is severe, the hip is more prone to dislocation and labral lesions. The open packed position of the

hip joint is in 30 degrees of flexion, 30 degrees of abduction, and slight external rotation. The closed packed

position is with the hip in full extension, combined with slight external rotation and abduction.

The hip also has a variety of ligaments that attach to restrain certain movements and help keep the joint

stable. The primary ligaments of the joint are iliofemoral, pubofemoral, and ischiofemoral ligaments. All three of

these ligaments blend with the joint capsule and are taut in extension. Out of the three, the iliofemoral ligament is

the strongest. In standing posture, the femoral head moves anteriorly and pushes against the iliofemoral ligament.

Iliofemoral ligament is also taut in external rotation. The pubofemoral ligament is taut in hip abduction and

external rotation. The ischiofemoral ligament is the opposite, and is taut in hip adduction and internal rotation.

Knowledge of these ligaments is useful therapeutically during attempts to stretch the entirely of the hip capsule.

With full hip extension, combined with slight internal rotation and abduction, twists most of the ligaments into

their taut position and so this is called closed packed position. The opposite of this position would be to the open

packed position of the hip joint is in 30 degrees of flexion, 30 degrees of abduction, and slight external rotation.

The ligamentum teres and transverse acetabular ligament also stabilize the hip. The ligamentum teres runs from

the head of the femur directly to the acetabular fossa, which helps to maintain the alignment of the femoral head

in the fossa. The transverse acetabular ligament completes the acetabular ring, reinforcing the inferior aspect of

the joint.

Ligaments of the Femoral Acetabular

Ligaments Attachments Function Associated constraints of the joint Iliofemoral Anterior inferior iliac spine,

intertrochanteric line of the femur Reinforces the joint capsule Limits extension of the femur

Ischiofemoral Ischium posterior to the acetabulum, greater trochanter, iliofemoral ligament

Reinforces the joint Assists iliofemoral ligament in limiting extension of the femur

Pubofemoral Iliopubic eminence, superior pubic ramus, fibrous joint capsule

Reinforces the joint capsule Limits abduction of the femur


28

Ligamentum teres

Fovea of the femoral head, acetabular notch

Attaches the femoral head to the acetabular fossa

Prevents distraction/dislocation of the femoral head from the acetabulum

Transverse acetabular

Margins of the acetabular notch Completes the inferior part of the acetabulum

Resists caudal translation of the femoral head


Femoroacetabular impingement (FAI). In FAI, bone spurs develop around the femoral head and/or

along the acetabulum. The bone overgrowth causes the hipbones to hit against each other rather than to move

smoothly. Over time, this can result in the tearing of the labrum and breakdown of articular cartilage

(osteoarthritis). There are three types of FAI: pincer, cam, and

combined impingement. Pincer type of impingement occurs because

extra bone extends out over the normal rim of the acetabulum. The

labrum can be crushed under the prominent rim of the acetabulum.

Pincer type is more common in females. In cam impingement the

femoral head is not round and cannot rotate smoothly inside the

acetabulum. A bump forms on the edge of the femoral head that grinds the cartilage inside the acetabulum. Cam

impingement is more common in males. Combined impingement occurs when both pincer and cam types are

present, which is common. Impingement is most typically felt in hip flexion, adduction and external rotation.

People with FAI usually have pain in the groin area, although the pain may be lateral to the groin. Patients may

complain of a dull ache or sharp stabbing pain with turning, twisting, and squatting.

Labral tears. FAI, trauma or arthritis can all result in labral tears. Planting the leg on the ground and

twisting usually is a cause of traumatic tears. Major trauma such as motor vehicle accidents can also tear the

labrum. As people develop arthritis; they can also develop labral tears. Patients usually complain of clicking, pain,

feeling of giving out, symptoms get worse with prolonged walking, standing, sitting.

Osteoarthritis. In osteoarthritis, the cartilage in the hip joint gradually

wears away over time. As the cartilage wears away, it becomes frayed and rough

and the protective joint space between the bones decreases. This can result in bone

Figure 14 Hip FAI

Figure 15 Hip Osteoarthritis


rubbing on bone. To make up for the lost cartilage, the damaged bones may start to grow outward and form bone

spurs (osteophytes). Osteoarthritis develops slowly and the pain worsens over time and is most common in people

over the age of 50, though younger people are affected by it also. The most common symptom of hip

osteoarthritis is pain around the hip joint. Usually pain has a slow onset, but it may have a sudden onset. Pain and

stiffness may be worse in the morning or after sitting for a long period of time. Over time, painful symptoms may

occur more frequently including during rest or at night. Patients with OA can also present with limited range of

motion especially into internal rotation and flexion.

Hip fractures. Fractures are a very serious and common issue in the United States. The most common

mechanisms of injury for hip fractures are falls and collisions. The older population is more affected by this and

unfortunately the incidence may continue to rise due to the increased life expectancy. The patient with a hip

fracture will have pain over the outer upper thigh or in the groin. There will be significant discomfort with any

attempt to flex or rotate the hip. Fractures are usually treated with surgery. The type of surgery used to treat a hip

fracture is primarily based on the bones and soft tissues affected or on the level of the fracture. Approximately

40% of those with a hip fracture are able to perform their daily functioning needs however; about half will

continue to use an assisted device for walking.


30

Knee Joint Complex

Introduction

The knee joint is formed by articulations between the patella, femur and tibia (Figure 16). The knee is the

largest joint and the most frequently injured joint in the body.

The tibiofemoral portion of the knee joint is a hinge type

synovial joint. It is the most complex diarthrosis of the body.

The knee primary motions include flexion and extension with

some external and internal rotation. The knee is overall

mechanically referred to as a weak joint. The stability and

strength of this joint is fully dependent on the strength of the

muscles and tendons surrounding joint entirety, as well as the

ligaments connecting the tibia and the femur.

The knee has up to 14 bursae of various sizes in and around the knee joint complex. Bursae help provide

an extra amount of friction control for the joint to move fluidly. Bursae around the patella include the prepatellar

bursa, the superficial and deep infrapatellar bursae, and the suprapatellar bursa. Bursae of the complex that are not

in close anatomical proximity to the patella include the pes anserine bursa, the iliotibial bursa, the tibial and

fibular collateral ligament bursae and the gastrocnemius-semimembranosus bursa. These fluid filled sacs cushion

the joint and reduce friction between muscles, bones, tendons and ligaments.

The knee is important biomechanically during walking. In the stance phase, the knee is slightly flexed.

This allows shock absorption, energy conservation, and transmission of forces to the lower limb. In swing phase,

the knee is flexed in order to shorten the functional length of the lower limb, which helps the foot clear the

ground. Gait has functional requirements of both stability and mobility for the knee to allow proper energy-

efficient and safe propulsion over ground.

Figure 16 Knee Joint Articulations


Muscles of the Knee Joint Complex

Muscles Proximal attachment Distal attachment Action Segmental Innervation

Peripheral innervation

Sartorius anterior superior iliac spine

medial aspect of the proximal tibia

flexes and assists internal rotation of the knee

(L2-3 [4]) Femoral nerve

Rectus femoris

anterior inferior iliac spine and groove superior to the acetabulum

the base of the patella extends knee (L2-3-4) Femoral nerve

Vastus intermedius

anterior aspect of the proximal 2/3rds of the femoral shaft

lateral border of the patella actions- extends knee

Extends knee (L2-3-4) Femoral nerve

Vastus lateralis

Intertrochanteric line, greater trochanter, gluteal tuberosity and linea aspera

Base and lateral border of the patella

Extends knee (L2-3-4) Femoral nerve

Vastus medialis

Intertrochanteric line, spiral line, linea aspera and medial supracondylar line

Base and medial border of the patella

Extends knee (L2-3-4)

Femoral nerve

Tensor fasciae latae

ASIS & external lip iliac crest

iliotibial tract assists in maintaining knee extension

(L4-5-S1) Superior gluteal nerve

Gracilis body of the pubis & inferior pubic ramus

medial surface of tibia, distal to condyle, proximal to insertion of semitendinosus, lateral to insertion of sartorius

flexes & medially rotates the knee

(L2-3-4)

Obturator nerve

Biceps femoris

ischial tuberosity & sacrotuberous lig. (long head) ; lateral lip of linea aspera & lateral supracondylar line (short head)

lateral side of fibular head Both heads: Flex knee Long Head: Extends hip

Long head: (L5-S1-2-3) Short head: (L5-S1-2)

Long head: tibial branch of sciatic nerve Short head: Fibular branch of sciatic nerve

Semimembranosus

Posterior aspect of the medial tibial condyle

posterior aspect of the medial tibial condyle

Ischial tuberosity (L4-5-S1-2) Tibial division of the sciatic

Semitendinosus

ischial tuberosity proximal, medial tibia flexes & medially rotates knee

(L4-5-S1-2)

Tibial division of the sciatic

Gastrocnemius

posterior aspect of the condyles and joint capsule

Posterior calcaneal surface flexes knee (S1-2) Tibial nerve

Popliteus lateral femoral condyle and oblique popliteal ligament

Soleal line of the tibia In NWB, IR of tibia and knee flexion; in WB insertion is fixed: ER of femur and knee flexion; unlocks the knee from extension into early flexion

(L4-5-S1) Tibial nerve

Articularis Genu

Distal anterior shaft of femur

Proximal portion of synovial membrane of knee joint

Pulls articular capsule proximally

(L2-3-4) Femoral


32

Tibiofemoral Joint

Overview

The tibiofemoral joint is formed by the condyles of the femur and the tibial plateau. The joint is a

modified hinge joint with two degrees of freedom. The primary motion is flexion and extension in the sagittal

plane. Some internal and external rotation can occur with slight flexion of the knee. The quadriceps femoris is

considered to be the most important muscle for stabilization of the tibiofemoral joint. The knee is considered

most stable in a fully extended position. This is the position where the femur’s contact on the tibia, is most

congruent and the ligaments associated with the tibiofemoral joint are the most taut. In this position, many of the

tendons surrounding the joint act as supporting structures as well.

Neurovasculature. There are 10 vessels that come together to form the periarticular genicular

anastomoses around the knee to supply blood to the knee joint. These 10 vessels include: genicular branches of

the femoral, popliteal, and anterior and posterior recurrent branches of the anterior tibial recurrent and circumflex

fibular arteries. Other supporting features of the tibiofemoral joint including the joint capsule, the cruciate

ligaments, the outer portions of the menisci, and the synovial membrane are supplied by the middle genicular

branches of the popliteal artery. The tibiofemoral is innervated by all the nerves supplying the muscles that cross

the knee joint. Branches from the femoral nerve innervate the anterior aspect of the knee. The tibial nerve supplies

the posterior aspect, and the common fibular nerve innervates the lateral aspect. Articular branches from both the

obturator and saphenous nerves supply the medial aspect of the knee.



• Superficial fascia (fascia lata) o Subcutaneous tissue

• Deep fascia • Muscles and tendons

o Quadriceps femoris § Rectus femoris § Vastus lateralis § Vastus medialis § Vastus intermediate


o Hamstrings § Biceps femoris § Semimembranosus § Semitendinosus

o Gracilis o Sartorius o Gastrocnemius o Popliteus o Iliotibial band

• Vascular supply o Popliteal artery o Descending genicular o Anterior tibial recurrent artery o Posterior tibial recurrent artery o Circumflex fibular artery o Inferior medial genicular artery o Inferior lateral genicular artery o Middle genicular artery o Superior medial genicular artery o Superior lateral genicular artery

• Innervation o Obturator o Femoral o Tibial o Common fibular o Saphenous o Nerve to the popliteus o Nerve to gastrocnemius

• Ligaments o Medial collateral ligament o Lateral collateral ligament o Oblique popliteal ligament o Arcuate popliteal ligament o Coronary ligament o Transverse ligament of the knee o Meniscofemoral ligament

• Fibrous joint capsule o Synovial membrane o Ligaments

§ Anterior cruciate ligament § Posterior cruciate ligament

o Menisci § Medial menisci § Lateral menisci

o Bursa § Prepatellar bursa § Suprapatellar bursa § Superficial infrapatellar bursa § Deep infrapatellar bursa § Semimembranosus bursa § Pes anserine bursa


34

o Plicae § Suprapatellar plica § Infrapatellar plica § Medial plica

o Fat pads § Infrapatellar fad pad

o Synovial fluid o Articular cartilage

Joint Motions

Motion Primary Movers Secondary Movers Degrees Possible

Knee flexion

Hamstrings (semitendinosus, semimembranosus, long head of the biceps); short head of the biceps

Gracilis, sartorius, gastrocnemius, popliteus

135 degrees

Knee extension

Quadriceps femoris Weakly: tensor of fascia lata

0 degrees, hyperextension may be available up to 10-15 degrees

Knee external rotation

Biceps femoris when the knee is in a flexed position

NA 40 degrees; may be difficult to establish neutral rotation

Knee internal rotation

Semitendinosus and semimembranosus when knee is flexed; popliteus when non-weight bearing and with the knee extended

Gracilis, sartorius 30 degrees; may be difficult to establish neutral rotation

Biomechanics and Joint Configuration

The tibiofemoral joint primary motions are flexion and extension; which occur about the mediolateral axis

of rotation. The range of motion of the knee is 130 to 150 degrees of knee flexion and 5 to 10 degrees of knee

extension beyond neutral position. External and internal rotation of the knee occurs about a longitudinal axis of

rotation. These rotations increase with knee flexion. At 90 degrees of knee flexion, the knee can rotate internally

about 30 degrees and externally at about 45 degrees. Beyond 90 degrees of flexion, rotation decreases due to

limitations by soft tissues.

An important concept, which helps with the stability of the knee, is the screw home mechanism. During

the last portion of active range of motion into extension a rotation between the tibia and the femur occurs. This

rotation produces the screw home mechanism, or “locking” of the knee. The rotation happens during the last 30

degrees of knee extension. Anterior tibial glide persists on the tibia's medial condyle because its articular surface

is longer in that dimension than the lateral condyle. Prolonged anterior glide on the medial side produces external


tibial rotation. There are three factors that affect the rotation mechanism; the shape of the medial femoral condyle,

the passive tension of the anterior cruciate ligament, and the lateral pull of the quadriceps muscle. This rotation is

not under voluntary control. This helps the knee’s stability for standing upright. The screw-home mechanism

decreases the work of the quadriceps femoris muscle. The muscle can relax once the knee joint is fully extended.

To unlock the extended knee, the joint internally rotates first. The popliteal muscle rotates the femur externally or

rotates the tibia internally to initiate flexion from a fully extended starting position.

The distal femoral condyles create a convex surface and the proximal tibial plateau creates concave

surface. The tibial condyles slide posteriorly on the femoral condyles during flexion, and slide anteriorly during

extension. In unloaded movement, open chain, the concave surface will glide in the same direction of the rotation.

In loaded movement, closed chain, the convex surface will glide in the opposite direction of the rotation.

The medial meniscus has an oval shape (Figure 17) and it

attaches to the deep layer of the medial collateral ligament and

capsule. The lateral meniscus has circular shape and it attaches only

to adjacent capsule. The quadriceps and semimembranosus attach to

both menisci and the popliteus attaches only to the lateral meniscus.

These muscles help to stabilize the menisci.

Neurovasculature supply of the menisci is greatest at the

external borders, while the internal border has no blood and nerve supply. The menisci are designed to absorb

shock, therefore, they reduce the compressive stress across the joint. During walking the compressive forces at the

joint reach 2.5-3x the body weight and increase to 4x the body weight with stair climbing. The menisci help to

reduce the pressure on the articular cartilage by increasing the contact area, which protects the knee joint. In

addition, it also increases stability of the knee by deepening the tibial plateaus, decreasing friction by 20%, and

increasing contact area by 70%. Increasing the contact area helps to disperse force over a greater surface area, and

decrease the total force experienced by any one point in the joint. The menisci serve a vital role in maintaining the

integrity and functionality of the tibiofemoral joint.

Figure 17 Tibial Plateau Anatomy


36

The ligaments that surround the knee are

important in stabilizing the knee. The cruciate

ligaments also guide the knee in natural

arthrokinematics by creating tension, and contribute to

the proprioception of the knee. The anterior cruciate

ligament (ACL) runs from posterior femur to anterior

side of the tibia (Figure 18). Its tension changes as the

knee flexes and extends. The anteromedial bundle is taut in

flexion and the posterolateral bundle is taut in extension. It is mainly taut as the knee reaches to full extension.

The posterior cruciate ligament (PCL) runs from the posterior intercondylar area of the tibia to the lateral side of

the medial femoral condyle (Figure 18). Most fibers of this ligament become taught with increasing knee flexion.

Tension peaks between 90 and 120 degrees of knee flexion. The primary role of the collateral ligaments is to limit

excessive motion of the knee in the frontal plane. The ligaments also play a role in

providing resistance to extreme external and internal rotation of the knee. The

medial collateral ligament (MCL) is a flat, broad ligament (Figure 19). It had two

layers, superficial and deep, the run from the femur to the tibia and the medial

meniscus. The superficial fibers blend with the medial patellar retinaculum fibers.

The deep fibers attach to the posterior-medial joint capsule, medial meniscus, and

tendon of the semimembranosus muscle.

The MCL resists valgus force. Since the

deeper fibers are shorter, they are more commonly injured than the

superficial fibers during excessive valgus trauma. The lateral collateral

ligament (LCL) is a round ligament that runs from the lateral epicondyle

of the femur and the head of the fibula (Figure 20). The LCL does not

attach to the lateral meniscus. It resists varus force.

Figure 18 Ligamentous Contribution to Knee

Figure 19 Medial Collateral Ligaments

Figure 20 Lateral Collateral Ligament


The knee has a crucial role during gait. During heel contact, the knee is in 5 degrees of flexion and it

continues to flex to 15 or 20 degrees during loading response. The quadriceps eccentrically control this flexion.

This helps with weight acceptance as the weight of the body shifts to the lower extremity. After slight flexion, the

knee extends until heel off. The knee then begins to flex again to 35 degrees during toe off. By mid swing knee

flexion reaches a maximum knee flexion of 60 degrees. This knee flexion is to shorten the length of the lower

limb and assist toe clearance. In mid and terminal swing the knee extends again. During gait, the knee requires

range of motion from full knee extension to 60 degrees of knee flexion. Gait impairments are noted when a lack

of knee range is available. A lack of knee flexion and extension will impair toe clearance and functional length.

Ligaments of the Tibiofemoral Ligament Proximal attachment Distal attachment Function

Anterior cruciate ligament (ACL)

posterior femur anterior side of the tibia Resist extension Resist extremes of varus, valgus, and axial rotation

Posterior cruciate ligament (PCL)

anteroinferior femur posterior side of the tibia Resist knee flexion Resist extremes of varus, valgus, and axial rotation

Lateral collateral Ligament (LCL)

Femur Fibula resist varus resist knee extension resist extremes of axial rotation

Medial collateral ligament (MCL)

Femur *Two layers (deep and superficial)

Tibia and the medial meniscus Resist valgus Resist knee extension Resists extremes of axial rotation

Oblique popliteal ligament Tendon of the Semimembranosus Posterior lateral condyle of the femur

Stabilizes the posterior aspect of the knee joint Limits external rotation of the tibia

Transverse ligament of the knee

Anterior edge of menisci crosses anterior intercondylar area

holds menisci together during knee movement

Coronary ligament of the knee

Inferior edges of the medial lateral menisci to the joint capsule of the knee

limiting rotation of the knee stabilizes medial and lateral menisci

Arcuate popliteal ligament Posterior fibular head posterior surface of the knee reinforces posterior lateral joint capsule

Meniscofemoral ligament: 1. Anterior 2. Posterior

Posterior horn of the lateral meniscus Extends from the posterior horn of lateral meniscus

Distal edge of the femoral PCL Medial femoral condyle

Stabilizes the lateral meniscus


38


Knee Fracture. With injury to the knee, it is important to rule out a suspected fracture. There are two

prediction rules for use in determining the need for a radiograph of the knee; the Ottawa Knee Rules, and the

Pittsburgh Knee Rules.

Ottawa Knee Rules

• age 55 or older

• isolated tenderness of the patella

• tenderness over the fibular head

• inability to flex knee >90 degrees

• inability to weight bear immediately, or in the emergency room for 4 steps

Pittsburgh Knee Rules

• Blunt trauma or fall as the mechanism of injury as well as either of the following:

• older than 50 years or younger than 12 years

• inability to walk 4 weight bearing steps in the emergency department

Medial Collateral Ligament Injuries (MCL). The most common mechanism of injury to MCL is a force to

the lateral aspect of the knee, creating a valgus force and placing strain on the MCL. This ligament may also be

injured by a rotational stress at the knee. In order to test for this injury, a valgus stress test can be completed in

both full extension and in 25-30 degrees of knee flexion. If there is laxity in the full extension position, this

indicates a possible sprain of the MCL, the cruciate ligaments, or the medial capsule. If there is laxity in 25-30

degrees of flexion, this indicates an MCL sprain specifically. Most injuries to the MCL can be managed non-

operatively with bracing due to the good blood supply to the MCL.

Lateral Collateral Ligament Injuries (LCL). This ligamentous injury is much less common than injury

to the MCL. The most common mechanism of injury is a force to the medial aspect of the knee, creating a varus

force and placing strain on the LCL. This injury is rarely isolated and may also cause injury to the cruciate

ligaments and knee joint capsule. In order to test for this injury, a varus stress test can be completed in both full

extension and in 25-30 degrees of knee flexion. If there is laxity in knee full extension, it may indicate damage to


the LCL, cruciate ligaments, or lateral capsule. If there is laxity of 25-30 degrees of knee flexion, it indicates

specifically an LCL sprain. Apley’s distraction test and the dial test are other tests that can also be completed.

With this injury, it is important to rule out fibular nerve injury due to the close location of the fibular nerve. The

LCL does not have a good blood supply and may need surgical repair.

Anterior Cruciate Ligament Injuries (ACL). Most injuries to the ACL are non-contact rotational forces

to the knee or the knee being put into a position of hyperextension. This may be an isolated injury or other

structures such as the joint capsule, the menisci, or the MCL may also be injured. With injury to the ACL, the

patient may state there was a “pop” or state “my knee gave out”. This injury is often accompanied by immediate

onset of swelling in the knee and is often treated surgically depending on the level of performance of the patient.

An injury to the ACL is more common in women than men due to specific anatomical differences. In order to test

for injury to the ACL, and anterior drawer test and Lachman’s test can be completed in order to look for excess

anterior displacement of the tibia on the femur. A pivot shift test is also used to determine if there is injury to the

ACL. For post-surgical rehabilitation, open chain knee extension is contraindicated.

Posterior Cruciate Ligament Injuries (PCL). The PCL is one of the strongest ligaments in the body.

The most common mechanism of injury to the PCL is hitting the dashboard in a motor vehicle accident or falling

on a bent knee, placing a posterior force on the tibia. This ligament can also be damaged as the result of a

rotational force or hyperextension. Special tests used in order to test for injury to this joint include, posterior

drawer test and the sag sign, looking for posterior displacement of the tibia on the femur. Depending on the

severity of the injury, injury to the PCL may be treated surgically or nonsurgically. For post-surgical

rehabilitation, open chain knee flexion is contraindicated.

Medial and Lateral Meniscus Injuries. The outer ⅓ of the menisci is the only area of the menisci that

has a good blood supply and a good potential to heal without surgery. The middle ⅓ of the menisci may have

healing potential and the inner ⅓ of the menisci has no blood supply and will not heal, requiring surgical

management. The most common mechanism of injury to the menisci is a forced rotation while flexing or

extending the knee. Forced tibia external rotation usually results in injury to the medial meniscus, and forced

tibial internal rotation usually results in injury to the lateral meniscus. With a meniscal injury, the patient may


40

complain of a “locking” feeling in the knee and a slower onset of swelling. Four clinical features suggestive of a

meniscal injury include: joint line tenderness, mild to moderate effusion that occurs over 1-2 days, positive

McMurray’s, Apley’s, Thessaly’s test, or functional squat, and quadriceps atrophy over the first week or two

following the injury.

Patellofemoral Joint

Overview

The patellofemoral joint is between the articular side of the patella and the intercondylar groove of the

femur. This joint is arthrodial (plane), non-axial, multiplanar. The movement of the joint is dictated by the

trochlear groove. The patellofemoral joint slides superiorly when the knee extends and inferiorly when the knee

flexes. A slight amount of medial and lateral deviation, as well as tilting, takes place during normal movement.

The joint is stabilized by the forces produced by the quadriceps muscle, the fit of the joint surfaces, and passive

restraint from the surrounding retinacular fibers and capsule.

The patella is the largest sesamoid bone in the body. The patella is attached to the tibial tuberosity by the

patellar tendon and is buried within the quadriceps tendon superiorly. Two facets exist on the posterior articular

surface of the patella (Figure 21). The lateral facet is larger and slightly concave and it moves along the lateral

condyle of the femur. The medial facet has different variations. It moves along the medial condyle of the femur.

Most patellae also have an odd facet, which is a

second vertical ridge between the medial border

that separates the medial facet from an extreme

medial edge. An important stabilizer of the

patella is the vastus medialis obliquus muscle,

which helps with the patella alignment.

Neurovasculature. The circulatory blood supply to the patella is made up of branches of six main

arteries: the descending genicular, the superior medial and lateral genicular, the inferior medial and lateral

genicular, and the anterior genicular. These branches anastomose, forming the prepatellar arterial network and,

Figure 21 Patellar Anatomy


with the transverse infrapatellar artery, form the extraosseous patellar supply. Other smaller arteries originating

from the popliteal and quadriceps arteries supply the patella entering at the base and the lateral sides. The

infrapatellar branch of the saphenous nerve innervates the anterior aspect of the knee, which is a sensory nerve.

Tissue Layers

• Skin o Epidermis o Dermis o Hypodermis

• Superficial fascia- fascia lata o Subcutaneous tissue

• Deep fascia • Muscles and tendons

o Quadriceps tendon • Arterial supply

o Descending genicular artery o superior medial genicular artery o lateral genicular artery o Inferior medial genicular artery o Anterior genicular artery o Popliteal artery

• Innervation o Saphenous nerve o Posterior tibial nerve o Obturator nerve o Femoral nerve

• Ligaments

o Patellar ligament • Fibrous joint capsule

o Synovial membrane o Ligaments

§ Medial patellofemoral ligament § Lateral patellofemoral ligament § Medial patellar retinaculum § Lateral patellar retinaculum § Iliotibial tract

o Bursa § prepatellar bursa § suprapatellar bursa § superficial infrapatellar bursa § deep infrapatellar bursa

o Plicae § suprapatellar plica § infrapatellar plica § medial plica

o Fat pads


42

§ Infrapatellar fad pad o Synovial fluid

Joint Motion

Joint motion Primary Movers Secondary Movers Degrees Possible

Superior glide Quadriceps muscle NA

Inferior glide (with knee flexion) Passive as quadriceps relax Hamstring to flexion the knee and thereby allow glide of the patella

NA

Biomechanics

The contact area of patellofemoral joint is different among the different arcs of motion at the knee. At 135

degrees of knee flexion, the contact area of the patella on the femur is mostly at the superior pole. At this position,

the patellar lateral and “odd” facet contact the femur. At 90 degrees of knee flexion, the contact area of the patella

starts to shift to its inferior pole (Figure 22). Between 90 and 60 degrees of knee flexion, the contact area is the

greatest since the patella is within the

intercondylar groove of the femur (Figure 22).

Even though the patella is in its greatest contact

area within this arc motion, only one third of the

patella surface area is in contact with the femur.

At 20 to 30 degrees of knee flexion, the contact

area of the patella migrates to the inferior pole as

illustrated in Figure 22. This leads to a decrease in the mechanical engagement with the intercondylar groove. In

full knee extension, the patella rests against the suprapatellar fat pad. In this position, the quadriceps muscle is

relaxed and the patella can move easily, which makes this position the least stable for the patella.

The patella glides inferiorly and superiorly with knee flexion and superiorly extension. During flexion,

the posterior motion of the tibia causes the patellar ligament to pull the patella inferiorly. During extension, the

quadriceps muscle pulls the patella superiorly. Lateral and medial glides are not directly associated with knee

joint motion. From extension to flexion, the patella glides slightly medially and then laterally. The patella laterally

Figure 22 Patellar Force-‐Angle Relationships


rotates approximately 5 degrees as the knee flexes from 20 to 90 degrees due to the asymmetrical configuration of

the femoral condyles. Since there is a variation of the patella and femur among the population, it is hard to state

the concave/convex relationship of this bone. Also, the patella has the medial, lateral, and sometimes the odd facet

that have varying degrees of convexity and concavity. All these facets do not have maximal contact with the

femur at once throughout the knee range of motion, which adds another factor for the conclusive understanding of

the joint relationship.

Interposed between the quadriceps tendon and the femoral condyles the

patella acts as a “spacer”. This helps to protect the tendon by reducing the

friction and compressive stress and minimizes the concentration of stress by

transmitting forces evenly to the underlying bone. The “spacer” between the

femur and quadriceps muscle increases the internal moment arm of the knee

extensor mechanism, shown in Figure 23. This allows more effective knee

flexion and increased quadriceps strength by 33–50%. The internal moment arm

refers to the perpendicular distance between the mediolateral axis of rotation and the line of force of the muscle.

The internal moment arm of the extensor muscles change throughout the flexion-extension arc of motion of the

knee. The internal moment arm is the greatest between 20 and 60 degrees of knee flexion. Few factors affect the

moment arm length: the shape of the patella, the position of the patella, the shape of the distal femur, and the

migrating mediolateral axis of rotation at the knee.

One of the main functional roles of the patella is to protect the knee from high

compressive forces. The patellofemoral contact pressure is 0.5 times body weight while

walking. It increases to 2.5 to 3.3 times body weight with stair ascending and

descending and up to 7 times body weight with running. The magnitude of the force is

affected by the amount of knee flexion with quadriceps muscle activation. With knee

flexion, the quadriceps tendon and the patellar tendon pull the patella, as Figure 24

illustrates. The combination of the forces leads to joint compression force at the

Figure 23 Quadriceps Moment Arm

Figure 24 Forces Acting on Patella


44

intercondylar groove of the femur. With an increase in knee flexion, the force demands increase throughout the

extensor mechanism and on the patellofemoral joint. The joint distributes compressive stress on the femur by

increasing contact between patellar tendon and femur. The compressive forces and the contact area are at

maximum between 60 and 90 degrees of knee flexion. Since the contact area of the patellofemoral joint is the

greatest when the compression force is the highest, the joint is protected from stress induced cartilage

degeneration.

Abnormal “tracking” of the patella will occur when the forces are not

distributed evenly and with structural abnormalities. This can increase the joint

contact stress and lead to degenerative lesions and pain. Excessive lateral

tracking of the patella can be caused due to lateral line of pull of the quadriceps

muscle relative to the patella. This line of pull is clinically meaningful and often

measured. This is referred to as the Q angle. The Q Angle is the angle between

the quadriceps muscle and the patellar tendon (Figure 25). It is from the ASIS to

the midpoint of the patella and from the tibial tuberosity to the midpoint of the

patella. It tends to be greater in females, typically 15-17 degrees, due to wider

pelvis. The typical Q angle of the male is 10-14 degrees.

The knee is normally in 5-10 degrees of slight valgus. Any

deviation from the normal alignment is either genu valgum or genu

varum. Genu valgum refers to a frontal deviation of the position of the

knee (Figure 26). Commonly referred to as “knock-knee” due to the

distal segments being positioned more laterally. Genu varum refers to

a frontal deviation of the position of the knee (Figure 27). Excessive

valgus can cause excessive stress on the patellofemoral joint and the

ACL. Genu varum, referred to as “bow-leg” is the opposite condition.

During the loading phase of the gait cycle with genu varum, the Figure 26 Genu Valgum

Figure 25 Q-‐Angle Measure

Figure 27 Genu Varum


ground reaction force passes medially to the knee. This ground reaction forces creates varus torque at the knee .

This creates tension in the lateral collateral ligament and iliotibial band. This asymmetrical load on the knee can

also cause wear of the articular cartilage, which can lead to osteoarthritis of the medial knee.

Abnormal alignment of the knee in the sagittal plane is referred to as genu recurvatum. This is

hyperextension of the tibiofemoral joint beyond 10 degrees of neutral placing excessive stress on the structures in

the popliteal space. The main cause of genu recurvatum is a great knee extensor torque that stretches the posterior

structures of the knee over time.

Ligaments of the Patellofemoral Joint Ligament Proximal

attachment Distal attachment Function

Medial patellofemoral ligament Femoral medial epicondyle

Medial edge of patella Restraint to lateral patellar displacement.

Lateral patellofemoral ligament Femoral lateral epicondyle

Lateral edge of patella Restraint to medial patellar displacement.

Patellar ligament (patellar tendon)

Apex of the patella Tibial tuberosity Work with the quadriceps muscle to extend the knee

Medial patellar retinaculum Medial edge of the patella

medial epicondyle of the tibia Stabilizes patella in transverse plane; lateral translation of the patella

Lateral patellar retinaculum Iliotibial band Longitudinal fibers of vastus lateralis

Stabilizes patella in transverse plane; medial translation of the patella

Iliotibial tract Tensor fascia latae Fibular head Resists medial displacement of patella


Patellar subluxation/dislocation. Patellar subluxation/dislocation is the slippage of the patella out of the

trochlear groove. It usually presents with significant swelling and often involves tearing of the VMO in addition

to medial retinaculum/medial patellofemoral ligament. Lateral displacement is the most common. It commonly

occurs with the knee in 20 to 30 degrees of flexion and may also have valgus load at the knee. Some risk factors

include: patellar hypermobility, tight lateral retinaculum, flattened posterior patella or shallow trochlear groove

between femoral condyles, increased Q angle, tibial torsion and faulty movement pattern. Treatment usually

involves immobilization of the knee between 1 to 6 weeks. The initial need is to reduce inflammation, then restore


46

range of motion and strengthen quads, hamstrings, and hips. It may be necessary to use a brace if the knee is

unstable. Subluxation is treated as patellofemoral pain while being aware of instability. With repeated

subluxation/ dislocation of the patella may need a surgery to repair the medial patellofemoral ligament.

Patellar tendinitis/tendinosis. Patellar tendinitis is an acute injury to the patellar tendon accompanied by

inflammation. Tendinosis is chronic degeneration without inflammation, beyond 10-15 days. Tendinosis is an

accumulation over time of microscopic injuries that don't heal properly. Inflammation is involved in the initial

stages of the injury. The injury is usually at the inferior pole of the tendon. The site of irritation may also be at the

tibial insertion, superior pole of the patella or in tendon mid-substance. It is usually an overuse injury caused by

repetitive strain or eccentric activity. It is more common in running and jumping activities. It occurs with

decreased quadriceps flexibility and occasionally with strength deficits. There are three phases that may occur:

pain after activity, pain during and after functional activity, pain leading to functional disability. Treatment

usually involves conservative management. Rest and activity modification are necessary.

Osgood-schlatter’s disease (apophysitis). Osgood-Schlatter’s disease is the traction of the patella tendon

on immature bone. It involves pain and inflammation at the tendon-bone interface below the kneecap in children

and adolescents experiencing growth spurts during puberty. It usually occurs in children between the ages of 12

and 16. It is more common in boys. It usually occurs in children who participate in activities that involve running,

jumping and change in direction. Treatment involves rest and activity modification, gentle stretching of extensor

mechanism, correction of muscle imbalances and alignment issues, and modalities for pain and inflammation.

Patellofemoral pain syndrome. The patellofemoral pain syndrome is pain in the anterior portion of the

knee around the patella or kneecap. The pain may also involve inflammation and instability of the muscles that

surround the knee. It can be caused by congenital, traumatic, or mechanical stress. For instance, the pain can be

caused by overuse, injury, excess weight, incorrect alignment of the kneecap (patellar tracking disorder), or

changes under the kneecap. The pain is aggravated especially when the knees are bent during sitting, squatting,

jumping, and descending stairs. Intervention includes restoring muscle balance within the quadriceps and hip

groups, improving range of motion, and modifying pain-inducing activities.


Bursitis. Knee bursitis is inflammation of the prepatellar, suprapatellar and infrapatellar bursa of the

knee. The symptoms may include pain with activity, rapid swelling on the front of the kneecap, tenderness and

warmth to touch. Bursitis can occur when the bursa becomes irritated and produces too much fluid. This causes

the bursa to swell and put pressure on the adjacent parts of the knee. Bursitis is usually caused by repetitive,

minor impact on the area, or from a sudden, more serious injury. It is most often caused by pressure from constant

kneeling. bursitis can also be caused by a bacterial infection. Treatment includes discontinue of activities that

worsen symptoms, modalities, elevation, patient education and anti-inflammatory medications.


48

Foot and Ankle Joint Complex Overview

The ankle and foot, as an integrated complex, serve the crucial role of being a dynamic interface between the

lower extremity and the ground. The complex is a fascinating structure because it is capable of being pliable

enough to absorb repetitive loading and irregular ground forces, yet also be rigid enough to support body weight

and to propel the body during gait and movement. The three major joints of the ankle are the talocrural, subtalar,

and transverse tarsal joints. The talocrural joint permits motion primarily in the sagittal plane (dorsiflexion and

plantarflexion), the subtalar joint permits motion in an oblique axis (pronation and supination), and the transverse

tarsal joint also takes an oblique path of motion, cutting nearly equally through all three cardinal planes in a true

pronation/supination motion. The talus is mechanically involved in all three of these joints. Thus, the unique

shape of the talus is critical to the mechanics of the ankle joint as a whole. During closed chain motion, the leg

and talus as a single unit must rotate over the relatively stationary calcaneus. These three joints work together in

order to accommodate for the unique patterns of movement that a person must make on a daily basis. Motion

from all three joints of the ankle is critical in order to manage the unique task of gait.

The foot also contributes largely to the mobile and stable characteristics of the foot and ankle complex. The

foot must have pliability in order to adapt to various surfaces, as well as stability to form a rigid lever for push off

during gait. The ankle and foot have numerous joints and ligaments. The foot is divided into the hindfoot, midfoot

and forefoot. The hindfoot is comprised of the calcaneous and talus; creating the subtalar joint. The midfoot

contains the navicular, cuboid, and cuneiforms; creating the transverse tarsal, distal intertarsals and

tarsometatarsal joints. The forefoot consists of the metatarsals and phalanges; comprising the intermetatarsal,

metatarsophalangeal, and interphalangeal joints. The primary motions of this region are supination and pronation

of the foot, which are dynamic movements with multiple components. The motions and arthrokinematics required

at these joints for gait will be discussed in detail throughout this section. The extrinsic muscles in this region cross

multiple joints and therefore produce multiple actions. Other muscles have more localized actions, such as the

intrinsic muscles of the foot.


Muscles of the Ankle Joint Complex

Muscle Proximal Attachment Distal Attachment Innervation Action Anterior Crural Muscles

Extensor Digitorum Longus

Lateral tibial condyle, proximal ¾ of the fibula and interosseus mem

Dorsal digital expansions of toes 2-5

Deep fibular nerve (L4-5-S1)

Dorsiflexes ankle, and extends digits 2-5 (IP and MP)

Extensor Hallucis Longus

Middle ½ of fibular surface & interosseous mem

Distal phalangeal base of the 1st toe


Dorsiflexes ankle and extends great toe (MP and IP)

Fibularis Tertius

Distal fibula and interosseus membrane

Base of the 5th metatarsal


Dorsiflexes ankle and everts foot

Tibialis Anterior

Lateral condyle and proximal 2/3 of the tibia’s lateral surface and interosseus membrane

Medial cuneiform and adjacent 1st metatarsal


Dorsiflexes ankle and inverts foot

Lateral Crural Muscles

Fibularis Longus

Head and proximal 2/3 of the fibula

Lateral aspects of the 1st metatarsal and adjacent medial cuneiform

Superficial fibular (fibular) nerve (L4-5-S1)

Everts foot, plantarflexes ankle and depresses 1st metatarsal head

Fibularis Brevis

Distal 2/3 of the fibula Lateral base of the 5th metatarsal

Superficial fibular (fibular) nerve (L4-5-S1)

Everts foot and plantarflexes ankle

Posterior Crural Muscles

Flexor Digitorum Longus

Posterior tibia distal to the soleal line

Plantar surfaces of the distal phalangeal bases

Tibial nerve (L5-S1 [2]) Plantarflexes ankle and flexes digits 2-5 (MP and IP)

Flexor Hallucis Longus

Distal 2/3 of the posterior fibular surface and interosseus membrane

Plantar aspect of the distal phalangeal base of the 1st toe

Tibial nerve (L5-S1-2) Plantarflexes ankle and flexes great toe (MP and IP)

Gastrocnemius Posterior aspect of the femoral condyles and joint capsule

Posterior calcaneal surface

Tibial nerve (S1-2) Flexes knee and plantarflexes ankle

Plantaris Lateral supracondylar line Posterior calcaneal surface

Tibial nerve (L4-5-S1 [2])

Flexes knee and plantarflexes ankle

Popliteus Lateral femoral condyle and oblique popliteal ligament

Soleal line of the tibia

Tibial nerve (L4-5-S1) In NWB, IR of tibia and knee flexion; In WB insertion is fixed: ER of femur and knee flexion; Unlocks knee extension to early flexion

Soleus Post aspect of the head & proximal ¼ of the fibula and tibial soleal line

Posterior calcaneal surface

Tibial nerve (L5-S1-2) Plantarflexes ankle

Tibialis Posterior

Interosseous membrane, lateral tibial surface and medial fibular surface

Navicular, intermediate cuneiform and bases of metatarsals 2-4

Tibial nerve ([L4]L5-S1) Inverts foot and plantarflexes ankle


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Muscles of the Foot Joint Complex

Muscle Proximal Attachment Distal Attachment Innervation Action Muscles of the Foot

Extensor digitorum brevis

Anterolateral surface of the calcaneus, lateral talocalcaneal ligament, and apex of the inferior extensor mechanism

By four tendons to the first through fourth digits via the lateral sides of the extensor digitorum longus tendons to the second, third and fourth digits. The medial slip is the extensor hallucis brevis.

Deep fibular Nerve (L4, L5, S1)

Extension of the second through fifth digits at the metatarsophalangeal and interphalangeal joints

Extensor hallucis brevis

Anterolateral surface of the calcaneus, lateral talocalcaneal ligament, and apex of the inferior extensor retinaculum

Dorsal surface of the base of the proximal phalanx of the great toe

Deep fibular nerve (L4, L5, S1)

Extension of the great toe at the metatarsophalangeal and interphalangeal joints

Flexor digitorum brevis

Medial process of the tuberosity of the calcaneus, central part of the plantar aponeurosis, and adjacent intermuscular septa

Middle phalanx of the second though fifth digits

Medial plantar nerve (L4, L5, S1)

Flexion of the second through fifth digits at the proximal interphalangeal joint

Flexor hallucis brevis

Medial part of the plantar surface of the cuboid bone, adjacent part of the lateral cuneiform bone, and tendon of the tibialis posterior

Medial and lateral sides of the base of the proximal phalanx of the great toe


Flexion of the great toe at the metatarsophalangeal joint

Quadratus plantae – medial head (flexor accessorius)

Medial surface of the calcaneus and medial border of the long plantar ligament

Tendon of the flexor digitorum longus Lateral plantar nerve (S1, S2)

Assists flexor digitorum longus in flexion of the digits

Quadratus plantae – lateral head (flexor accessorius)

Lateral process of calcaneal tuberosity and lateral border of the longer plantar ligament

Tendon of the flexor digitorum longus Lateral plantar nerve (S1, S2)

Assists flexor digitorum longus in flexion of the digits

Flexor digiti minimi

Base of the fifth metatarsal bone, and from the sheath of fibularis longus

Lateral side of the base of the proximal phalanx of the fifth digit Blends with tendon of abductor digiti minimi

Lateral plantar nerve (S1, S2)

Flexion of the fifth digit at the metatarsophalangeal joint

Abductor digiti minimi

Calcaneal tuberosity Lateral side of proximal phalangeal base of the fifth digit


Abducts and flexes the fifth digit

Abductor hallucis

Medial process of calcaneal tuberosity, flexor retinaculum, plantar aponeurosis, and adjacent intermuscular septum

Medial side of the base of the proximal phalanx of the great toe. Some fibers attach to the medial sesamoid bone, and a tendinous slip may extend to the base of the proximal phalanx of the great toe


Abducts and flexes the great toe

Adductor hallucis – oblique head

From the bases of the second through fourth metatarsal bones and the sheath of the tendon of the fibularis longus

Lateral side of the base of the proximal phalanx of the great toe


Adducts the great toe

Adductor hallucis – transverse head

From the plantar metatarsophalangeal ligaments of the third through fifth digits and the deep transverse metatarsal ligament

Lateral side of the base of the proximal phalanx of the great toe


Adducts the great toe

Lumbricals – first

From the medial side of the first flexor digitorum longus tendon

Medial side of the proximal phalanx and dorsal expansion of the extensor

Tibial Nerve (L4, L5, S1)

Flexes the proximal phalanges at the


Proximal Tibiofibular Joint

Overview

The tibia and the fibula are connected with involvement of three components: the proximal tibiofibular

joint, the distal tibiofibular joint, as well as an interosseous membrane that spans the full length of the space

between the tibia and the fibula. The proximal tibiofibular joint is classified as a plane type synovial joint. This

joint is formed by the flat facet of the fibular head articulating with the lateral aspect of the lateral condyle of the

tibia as shown in Figure 28. A joint capsule surrounds this joint and is

reinforced by both anterior and posterior ligaments of the fibular head.

The tendon of the popliteus strengthens the joint posteriorly. The fibula

has very little weight bearing function and is only responsible for about

10% of the weight transmitted through the femur. Due to limited weight

bearing, the hyaline cartilage of the proximal tibiofibular joint is

dependent on joint motion to maintain nutrition of the cartilage. There is

little motion that occurs at this joint. Stability is needed to ensure forces

digitorum longus tendon of the second through fifth digits

metatarsophalangeal joint, and extends the interphalangeal joint

Lumbricals - second

From the adjacent side sides of the first and second flexor digitorum longus tendons

Medial side of the proximal phalanx and dorsal expansion of the extensor digitorum longus tendon of the second through fifth digits

Tibial Nerve (L4, L5), S1, S2

Flexes the proximal phalanges at the metatarsophalangeal joint, and extends the interphalangeal joint

Lumbricals – third

From the adjacent sides of second and third flexor digitorum longus tendons



Flexes the proximal phalanges at the metatarsophalangeal joint, and extends the interphalangeal joint

Lumbricals - fourth

From the adjacent sides of the third and fourth flexor digitorum longus tendons



Flexes the metatarsophalangeal joint of the digits, and extends the interphalangeal joints

Plantar interossei

Base and medial side of bodies of metatarsals 3-5

Dorsal digital expansions of digits 3-5 Lateral plantar nerve (S1, S2)

Adducts and flexes the metatarsophalangeal joints of digits 3-5

Dorsal Interossei

Metatarsal shafts, each with two heads originating from adjacent metatarsals

Proximal phalangeal bases and dorsal digital expansion of digits 2-4


Abducts and flexes the metatarsophalangeal joints of digits 3-5

Figure 28 Articulation of Tibia and Fibula


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from the biceps femoris muscle and the lateral collateral ligament of the knee are efficiently transferred from the

fibula to the tibia. Movement at the proximal tibiofibular joint occurs in combination with movement at the distal

tibiofibular joint. Most movement that does take place, occurs as a result of dorsiflexion of the ankle. With

dorsiflexion, the trochlea of the talus wedges between the medial and lateral malleoli, resulting in movement at

both the proximal tibiofibular and distal tibiofibular joints. The main blood supply of the proximal tibiofibular

joint is from the inferior lateral genicular and anterior tibial recurrent arteries. The common fibular nerve and the

nerve to the popliteus innervate this joint.



§ Adipose tissue § Loose connective tissue

• Superficial Fascia o Small saphenous vein o Sural nerve o Great saphenous vein

• Deep Fascia • Muscles and Tendons

o Anterior Compartment near proximal joint § Extensor digitorum longus muscle § Tibialis anterior muscle

o Lateral Compartment near proximal joint § Fibularis longus muscle § Biceps femoris tendon

o Posterior Compartment near proximal joint § Gastrocnemius muscle § Soleus muscle § Tibialis posterior muscle § Popliteus muscle and tendon

• Nerves o Common fibular nerve (close approximation to fibular head) o Nerve to popliteus

• Veins o Posterior tibial vein

• Arteries o Posterior tibial recurrent artery o Anterior tibial artery o Inferior lateral genicular artery

• Ligaments


o Lateral collateral ligament o Arcuate popliteal ligament o Posterior ligament of the head of the fibula o Anterior ligament of the head of the fibula

• Articular capsule of Proximal Tibiofibular Joint o Outer fibrous layer of capsule o Inner synovial membrane of capsule o Articular cartilage covering surface of tibia and fibula o Fibular head and tibia articulation

Joint Motion Motion Primary Movers Secondary Movers

Anterior Glide: with knee flexion and with dorsiflexion of the ankle

There are no primary movers that function to provide motion to the proximal tibiofibular joint independently

There are no muscles that act directly on the proximal tibiofibular joint to move the joint independently. Motion that occurs at this joint occurs secondary to knee flexion/ extension and ankle dorsiflexion/ plantarflexion.

Muscles that function to flex/extend the knee and muscles that function to dorsiflex/ plantarflex the ankle contribute to the motion at the proximal tibiofibular joint

Posterior Glide: with knee extension and with plantarflexion of the ankle

Biomechanics

Stability at the proximal tibiofibular joint is needed to ensure forces from the biceps femoris muscle and

the lateral collateral ligament of the knee are efficiently transferred from the fibula to the tibia. The proximal

tibiofibular joint is enclosed by a joint capsule that is thicker anteriorly than it is posteriorly. The anterior and

posterior ligaments of the fibular head, as well as the tendon of the popliteus muscle, cross over the joint

surrounding the joint capsule to provide stability to the joint and allow for the forces discussed to be transferred

from the fibula to the tibia. These ligaments also assist in resistance to the downward pull placed on the fibula by

8 of the 9 muscles that attach to it. Although the proximal tibiofibular joint is in closer relation to the knee joint,

this joint is most closely related to ankle biomechanics. Mobility must be maintained in both proximal and distal

tibiofibular joints to ensure proper ankle function. The distal tibia along with the malleoli creates a structure in the

ankle referred to as the ankle mortise. This is an adjustable anatomical structure that changes in size in correlation

with dorsiflexion or plantar flexion of the ankle. With dorsiflexion, the mortise expands to allow the talus to move

within the ankle mortise. With plantarflexion, there does not need to be as much movement within the mortise due


54

to the posterior aspect of the talus being narrower than the anterior portion. The

proximal tibiofibular and distal tibiofibular joints work in combination to allow this

change of the mortise to take place. These three joints are not able to move

independently of one another. Fusion of either tibiofibular joint may limit the range

of motion of the ankle into dorsiflexion by affecting the ability of the talus to move

within the ankle mortise. For proper gait, 10 degrees of dorsiflexion is required. In

phases of gait, dorsiflexion is required to allow the critical event of forefoot rocker

to take place in terminal stance, and the critical event of dorsiflexion to neutral in

the mid swing phase of gait. Therefore, although the proximal joint has a function

in stability, it also must maintain mobility for adequate ankle motion as illustrated

in Figure 29. The open pack position for this joint where most motion occurs is

with 25 degrees of knee flexion and 10 degrees of plantarflexion.

Joint Configuration

The articulations between the tibia and the fibula can be separated into the proximal tibiofibular joint, the

interosseous membrane, and the distal tibiofibular joint. The main focus of this section will be on the proximal

tibiofibular joint. The distal tibiofibular joint along with the interosseous membrane will be discussed in a later

section. The proximal tibiofibular joint is formed by the flat facet of the fibular head articulating with the lateral

aspect of the lateral condyle of the tibia. The tibial facet is slightly concave and the fibula is slightly convex.

Although, due to the fact this joint does

not have muscles that function to move

it, it does not follow the typical

concave and convex rules. This joint

moves in the anterior posterior

direction along the sagittal plane

around coronal axis with both movement

Figure 29 Forefoot Rocker: Critical Event of Gait

Figure 30 Concave fibular facet of tibia and convex fibular head


at the knee as well as movement at the ankle. As the knee flexes, the proximal fibula glides anteriorly and with

knee extension, the proximal fibula glides posteriorly. This motion is also seen with dorsiflexion and

plantarflexion of the ankle. As the fibular malleolus moves posteriorly as with dorsiflexion, the head of the fibula

glides anteriorly and vice versa.

Ligaments of the Proximal Tibiofibular

Ligament Proximal Attachment Distal Attachment Function

Anterior Ligament of the Fibular Head

Anterior portion of the lateral condyle of the tibia

Anterior portion of the head of fibula

Stability of the mortise, therefore stability of the ankle

Posterior Ligament of the Fibular Head

Posterior portion of the lateral condyle of the tibia

Posterior portion of the head of the fibula

Assist in ability to resist downward pull placed on the fibula by 8 of the 9 muscles attached to it. Allow slight upward movement of the fibula with dorsiflexion of the ankle

Tendon of Popliteus Lateral femoral condyle Soleal Line of tibia Provide stability to ensure forces from the biceps femoris muscle and LCL are efficiently transferred from fibula to tibia

Crural Interosseous Membrane

Interosseous border of the tibia

Interosseous border of fibula

Provides stabilization to the posterior aspect of the joint

Common Pathology

The proximal tibiofibular joint is susceptible to mostly indirect trauma

as a result of any severe ankle stress on the weight bearing extremity. If there is

direct trauma to the joint itself, it may result in dislocation, subluxation, sprain

or fracture. For a direct trauma injury to take place, the main mechanism of

injury is the result of a lateral force to the knee while in a flexed weight bearing

position. With initial examination, if there is tenderness over the fibular head, a

radiograph should be recommended in suspicion of a possible fracture to the

proximal fibula.

Dislocation. Dislocation of the proximal tibiofibular joint is considered

to be a rare injury. This injury is in relation to direct trauma and is mostly seen in athletes or those whom are very

active. Anterolateral dislocation is the most common of this joint. The mechanism of injury resulting in

dislocation is sudden internal rotation and plantar flexion of the foot, with external rotation of the leg and flexion

Figure 31 Close approximation of common fibular nerve and fibular head


56

of the knee. Fibular palsy can be a side effect of this injury due to the close relation of the fibular nerve to the

head of the fibula. Currently there are no clear guidelines for best treatment in the acute phase, although in most

cases it is stated that reduction can be achieved with application of force over the joint. If open reduction is not

successful, closed reduction may be necessary (Goldstein et al, 2011).

Distal Tibiofibular joint

Overview

The distal tibiofibular joint is made up of medial convex fibula and the concave fibular notch of the tibia.

It is a syndesmosis joint, which is a synarthrodial joint that is closely bound by an interosseous membrane. The

two bones do not actually come into contact with each other but are separated by fibroadipose tissue. There is no

capsule but rather the interosseous membrane, interosseous ligament as well as the anterior and posterior

tibiofibular ligaments that function together to create a stable

joint and allow minimal movement.

Neurovasculature. This joint receives blood supply from

the perforating branch of the fibular artery and the medial

malleolar branches of the anterior and posterior tibial arteries. It

receives its nerve supply from the deep fibular and tibial nerves.


o Epidermis § Stratum corneum § Stratum lucidum § Stratum granulosum § Stratum spinosum § Stratum Basale

o Dermis § Stratum papillae § Reticular layer

• Subcutaneous o Adipose

• Fascia and retinacula o Super extensor retinaculum o Infer extensor retinaculum o Flexor retinaculum

Figure 32 Distal Tibiofibular Joint


• Muscles and associated ligaments o Anterior compartment (dorsiflexors)

§ Tibialis anterior § Extensor digitorum longus § Extensor hallicus longus § Fibularis tertius

o Lateral compartment (everters) § Fibularis longus § Fibularis brevis

o Posterior compartment (plantarflexors) § Superficial § Gastrocnemius § Soleus § Plantaris

o Deep (invertors) § Tibialis posterior § Flexor digitorum longus § Flexor halluces longus

• Bone o Tibia o Syndesmosis o Fibula o Talus o Calcaneus

Joint Motions

* Motion at the distal tibiofibular joint cannot be created without associated motion at the talocrural joint. The main function of this joint is to move minimally in order to maximize stability of the talocrural joint.


The main function of the distal tibiofibular joint is to provide stability for the talocrural joint during

activity and therefore it is not intended to have much mobility. The little mobility that is allowed within this joint

comes from a mobile fibula on a stable tibia. The joint has one degree of freedom in rotation through the

transverse plane. Slight anteroposterior gliding in the sagittal plane occurs as well.

During dorsiflexion the fibula must glide superiorly and rotate laterally. This motion is pertinent to

allowing the wider anterior talus to become wedged in between the distal tibia and fibula. During wedging the

fibula spreads from the tibia anywhere between 1-4mm apart. This wedging along with resistance from the

Distal Tibiofibular Joint motion* Talocrural motion Associated Muscles Superior glide and external rotation Dorsiflexion at the talocrural joint

Tibialis anterior , Extensor digitorum longus, Extensor Hallucis Longus, Fibularis tertius

Inferior glide and internal rotation Plantarflexion at the talocrural joint

Gastrocnemius, Soleus, Plantaris, Tibialis posterior, Flexor digitorum longus, Flexor Hallucis Longus, Fibularis longus, Fibularis brevis


58

interosseous membrane and tibiofibular ligaments allows for optimal stability of the ankle and acceptance of high

compression forces throughout the stance phase of gait. During plantarflexion the fibula glides inferiorly and

rotates internally. This allows for effective push of at the end of the gait cycle.

Ligaments of the Distal Tibiofibular


Interosseous ligament

Interosseous crest of the distal tibia An extension of the interosseous membrane just thicker banding

Interosseous crest of the distal fibula An extension of the interosseous membrane just thicker banding

Binds the tibia and fibula together – it is the strongest bond between the distal end of the tibia and fibula

Anterior tibiofibular Anterior distal medial tibia Anterior distal medial fibula Joint stabilization

Posterior tibiofibular Posterior distal medial tibia

Posterior distal medial fibula Joint stabilization

Inferior transverse ligament

medial surface of the upper part of lateral malleolus

Posterior border of the lower end of the tibia

Joint stabilization


High ankle sprains are the most common pathology of the distal tibiofibular joint. A high ankle sprain is

also known as a syndesmosis sprain because it damages the syndesmosis and all of the ligaments associated with

the distal tibiofibular joint. It is the least common form of an ankle sprain and takes much more time to recover

from. It is caused by hyper dorsiflexion in combination with extreme external rotation. They often co-occur with

other ligament damage and/or distal tibia and fibula fractures. A person that sustains this type of injury therefore

needs to seek radiographs to eliminate the need for surgery. The patient will present with proximal ankle pain that

is elicited during dorsiflexion and external rotation (because the talus will be separate the tibiofibular joint at

maximal dorsiflexion). The most common tests are the talar tilt test, tib/fib squeeze test and Klieger's test.

Immediate treatment consists of immobilization to limit dorsiflexion and possibly a period of non-weight bearing

depending on the severity.


The Talocrural Joint

Overview

The talocrural joint is comprised of the articulation between the tibia and fibula proximally and three

articular surfaces of the talus distally. Tibial and fibular portion of the joint is often referred to as the mortise

because of its resemblance to a mortise used by carpenters. Superiorly the trochlear surface of the talus articulates

with the base of the tibia. The lateral fibular facet of

the talus articulates with the lateral malleolus of the

fibula. The medial tibial facet articulates with the

medial malleolus of the tibia. Together these three

articulations create a hinge joint with one degree of

freedom allowing for only dorsiflexion and

plantarflexion in the sagittal plane. The joint is

surrounded by a weak and thin capsule and therefore

requires extensive ligamentous support in all directions.

Neurovasculature. The tibial nerve and the deep branch of the fibular nerve innervate the talocrural joint.

It receives its blood supply from the anterior and posterior tibial and fibular arteries.


o Epidermis § Stratum corneum § Stratum lucidum § Stratum granulosum § Stratum spinosum § Stratum Basale

o Dermis § Stratum papillae § Reticular layer

• Subcutaneous o Adipose

• Fascia and retinacula o Super extensor retinaculum

Figure 33 Talocrural Joint


60

o Infer extensor retinaculum o Flexor retinaculum

• Muscles and associated ligaments o Anterior compartment (dorsiflexors)

§ Tibialis anterior § Extensor digitorum longus § Extensor hallicus longus § Fibularis tertius

o Lateral compartment (everters) § Fibularis longus § Fibularis brevis

o Posterior compartment (plantarflexors) § Superficial § Gastrocnemius § Soleus § Plantaris

o Deep (invertors) § Tibialis posterior § Flexor digitorum longus § Flexor halluces longus

• Bone o Tibia o Syndesmosis o Fibula o Talus o Calcaneus

Joint Motions

Joint Motion Primary Movers Secondary Movers Dorsiflexion Tibialis anterior

Extensor digitorum longus Extensor hallucis longus Fibularis tertius

Plantarflexion Gastrocnemius Soleus

Plantaris Tibialis posterior Flexor digitorum longus Flexor hallucis longus Fibularis longus Fibularis brevis


The shape of the talus largely depicts the biomechanics and kinematics of the talocrural joint. The talus

forms a rounded dome superiorly and it is much wider anteriorly than it is posteriorly. Anteriorly the head of the

talus projects forward at approximately 23-30 degrees from the sagittal plane. The axis of motion passes through

the body of the talus and the ends of both malleoli. As the axis passes from lateral to medial it is slightly anterior

and superior to the true medial to lateral axis as depicted in Figure 34. The lateral malleolus is posterior and

inferior to the medial malleolus resulting in a 10-degree deviation from to the frontal plane and 6 degree deviation


from the horizontal plane. Due to this axial alignment the two true

movements of the talocrural joint are also associated with some accessory

motion. Dorsiflexion is associated with pronation (abduction and eversion)

and plantarflexion is associated with supination (adduction and inversion).

The talus is a convex bone that articulates with a concave mortise

(tibia and fibula). The talocrural joint possess one degree of freedom of

movement in the sagittal plane. Those motions are dorsiflexion and

plantarflexion. The normal range of motions for dorsiflexion and

plantarflexion are 10 to 20 degrees and 20 to 50 degrees respectively. Closed

pack position of the joint occurs during maximal dorsiflexion and open pack

occurs at 10 degrees of plantarflexion.

During open chain activity the convex talus moves on a concave mortise. This means that the roll and

slide/glide will occur in opposite directions. When the ankle moves into dorsiflexion the talus rolls anteriorly and

glides posteriorly while plantarflexion causes the talus roll posteriorly and glide anteriorly. However, this is the

opposite during closed chain activity where the talus is fixed and the tibia and fibula move on it. In this case the

concave mortise moves on the convex tibia creating roll and slide in the same direction. Therefore during

dorsiflexion the roll and glide both occur in the anterior direction and during plantarflexion in the posterior

direction.

During gait and weight bearing the talus moves from plantarflexion to dorsiflexion. At initial contact the

talocrural joint facilitates rapid plantarflexion to firmly plant the foot on the ground. After this point the mortise

advances over the talus into dorsiflexion. This causes the ligaments and plantarflexor muscles to become taut

allowing for optimal stability of the joint. As the mortise advances it moves to the widest anterior portion of the

talus and creates a wedge in between the tibia and fibula ultimately spreading them apart and enhancing joint

stability. This increased stability allows the joint to withstand compression forces up to 450% of a person’s body

weight.

Figure 34 Axis of Motion of Talocrural Joint


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Ligaments of the Talocrural

Ligament Proximal Attachment Distal Attachment Function Anterior Talofibular ligament

Anterior aspect of lateral malleolus

Neck of talus Prevents excessive inversion and adduction

Posterior Talofibular Ligament

Posteromedial side of the lateral malleolus

lateral tubercle of the talus

Stabilize the talus within the mortise Limits excessive abduction of the talus while in full dorsiflexion

Deltoid Ligament Tibionavicular portion

Medial malleolus Navicular Stabilize rear foot Limits excessive eversion

Deltoid Ligament Tibiocalcaneal portion

Medial malleolus Sustentaculum tali of the Calcaneus

Stabilize rear foot Limits excessive eversion

Deltoid ligament Tibiotalar portion

Medial malleolus Medial tubercle and adjacent part of talus

Stabilize rear foot Limits excessive eversion


Ankle sprains. Ankle sprains are the most common injury of the talocrural joint. Ankle sprains are

sprains or tears of the ligaments that support the joint. There are several types of ankle sprains delineated by

location and severity of injury.

The most common type of talocrural sprain is an inversion ankle sprain. It is most common because of

how the foot is normally positioned upon making contact with the

ground during running. Inversion ankle sprains occur when the foot

lands in excessive plantarflexion and eversion, which causes the

foot to roll inward. As a result the ligaments on the lateral side of

the talocrural joint are strained or torn. The grade or severity of

ankle sprain is depicted by the involvement of ligaments and

Figure 35 Lateral Talocrural Ligaments Figure 36 Medial Talocrural Ligaments

Figure 37 Ankle Sprains


amount of secondary symptoms. Grade 1 involves a stretching of only the ATFL and might be associated with

slight edema but not instability. Grade 2 is considered when there is partial tearing to the ATFL and CFL, slight

instability upon testing and moderate edema. Grade 3 involves complete tears to the ATFL, CFL, and PTFL,

definite instability and significant diffuse edema. A person with a grade 3 will not be able to bear weight without

significant pain.

The other type of sprain associated with the talocrural joint is called a medial or eversion ankle sprain. It

is similar to the lateral ankle sprain but occurs when forces are applied in plantarflexion and eversion. This

scenario damages the medial collateral ligaments (deltoid ligaments). These ligaments are very strong and

therefore this type of injury is commonly seen with an avulsion fracture to the medial malleolus (Potts fracture).

The same grades listed above apply to the eversion ankle sprain but instead involve the deltoid ligament.

Treatment of ankle sprains varies from physical therapy to surgical fixation depending on the severity of

the sprain. Typically eversion ankle sprains take longer to heal than inversion and require surgery more

frequently.

Subtalar Joint

Overview The subtalar joint (Figure 38), also referred to as the talocalcaneal joint, lies underneath the talus and

consists of three articulations between the calcaneus and the talus. These articulations are the posterior, middle,

and anterior articulations. The mobility of the subtalar joint is crucial during all aspects the gait cycle. During

gait, the calcaneus remains relatively fixed, therefore, the leg and the talus, as a

unit, must find a way to rotate over the fixed calcaneus in order for supination and

pronation to occur. The mobility at the subtalar joint allows for this to occur by

letting the foot assume positions that are independent of the orientation of the

ankle and leg, which is essential to many daily activities such as walking on

uneven surfaces and maintaining balance. The subtalar joint is also unique in that

it is designed to quickly transition from a “flexible shock-absorbing structure to a Figure 38 Subtalar Joint Structure


64

rigid propulsive one” (Maceira & Monteagudo, 2015). The orientation of the axis, which can be viewed in

Figures 39 and 40, of the subtalar joint makes pronation and supination triplanar, meaning that the movements cut

through each of the three cardinal planes. Pronation and supination occur in one

plane about an oblique axis.

Neurovasculature. The subtalar joint receives its blood supply from the

posterior tibial and fibular arteries. It is innervated on the plantar aspect by the

medial or lateral plantar nerve, and on the dorsal aspect by the deep fibular nerve.

Tissue Layers

� Epidermis and dermis � Subcutaneous tissue

o Adipose o Retinaculum (inferior extensor retinaculum)

� Fascia o Crural fascia

� Muscles o Dorsum (lateral to medial)

§ Tendon of fibularis brevis § Muscle of extensor digitorum brevis § Tendon of fibularis tertius § Tendon of extensor digitorum longus § Tendon of extensor hallucis longus § Tendon of tibialis anterior

o Plantar (lateral to medial) § Plantar aponeurosis § Superficial

• Muscle of abductor digiti minimi • Muscle of flexor digitorum brevis • Muscle of abductor hallucis

§ Second Layer • Muscle of abductor digiti minimi • Muscle of flexor digiti minimi brevis • Muscle of quadratus plantae • Tendon of flexor digitorum longus • Lumbricals • Tendon of flexor hallucis longus

§ Deep Layer • Tendon of fibularis brevis • Tendon of fibularis longus • Tendon of flexor hallucis longus • Tendon of tibialis posterior

� Ligamentous Layer

Figure 39 Subtalar Axis


o Long plantar ligament (plantar surface) � Joint capsule � Synovial membrane � Joint articular surfaces

Joint Motions

Joint Motion Primary Movers Secondary Movers Pronation Components: Eversion Fibularis Longus Fibularis Brevis Abduction Fibularis Longus Fibularis Brevis Dorsiflexion (minimal) Tibialis Anterior Extensor Digitorum Longus, Fibularis Tertius Supination Components: Inversion Posterior Tibialis Tibialis Anterior, Flexor Digitorum Longus,

Flexor Hallucis Longus, Triceps Suralis Adduction Posterior Tibialis Tibialis Anterior, Flexor Digitorum Longus,

Flexor Hallucis Longus Plantarflexion (minimal) Fibularis Longus Fibularis Brevis

Biomechanics

The kinematics of the subtalar joint is considerably different in

the open and closed chain positions. In the open chain position, a

muscle acts on the joint it crosses (Maceira & Monteagudo, 2015).

Pronation and supination during non-weight bearing activities occur as

the calcaneus moves relative to the fixed talus. Muscle action during closed

kinetic chain; as seen when the foot supports the body weight, is more complicated than in the open chain

situation. Motion of the subtalar joint during walking and weight bearing is restrained by external moments from

gravity and ground reaction forces (Maceira & Monteagudo, 2015). If the external moment acting on the joint is

higher than the internal moment generated by any muscle acting on that joint, then the fixed end of the muscle

will be the distal attachment and the proximal end of the muscle will move (Maceira & Monteagudo, 2015).

There are no muscles that insert directly onto the talus, so in the open chain situation when the talus is not fixed,

the talus moves because peritalar structures move (Maceira & Monteagudo, 2015). In closed chain conditions, the

force applied is not great enough to overcome the resistance of the external forces acting on the joint. The axis of

rotation for the subtalar joint is an oblique axis about which pronation and supination occur, as demonstrated in

Figure 40. The axis is typically described as a line that pierces the lateral-posterior inferior aspect of the heel and

courses through the subtalar joint in an anterior, medial, and superior direction, and is oriented 42 degrees from

Figure 40 Subtalar Joint Motion


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the transverse plane and 16 degrees from the sagittal plane. While the motion at the subtalar joint is described as

tri-planar because the motions of supination and pronation involve motions in all three planes, only two of the

three main components of pronation and supination are strongly evident. Inversion, eversion, abduction and

adduction are strongly relevant, while dorsiflexion and plantarflexion moments at this joint are relatively small

and thus typically considered clinically irrelevant. During walking, as briefly mentioned earlier, the subtalar joint

serves initially as a shock absorbing structure and then is converted into a rigid lever during the second and third

rockers of gait, allowing the foot to have the optimal mechanical efficiency for push off (Maceira and

Monteagudo, 2015). During the shock absorption stage, which lasts for approximately the first 30 to 35% of the

gait cycle, the subtalar joint pronates, which lowers the medial plantar arch enough to add flexibility to the

midfoot. In preparation for push off, the foot supinates and the arch rises, thus adding rigidity to the midfoot.

This “rigid-lever” action prepares the foot to support the large loads produced at push off.

Joint Configuration

As mentioned earlier, the subtalar joint consists of three articulating facets between the calcaneus and the

talus: the posterior, anterior, and middle facets, which can be observed in Figure 41. The posterior articulation of

the subtalar joint is the largest of the articulating facets, occupying approximately 70% of the total articular

surface area. The posterior facet of the talus is concave, and rests

on the convex posterior facet of the calcaneus. While there are

three facets that articulate at the STJ that all contribute to the

mechanics of the joint, the posterior facet is often considered to be

the most clinically relevant and the focus of intervention in

treating mobility of the hindfoot because of its extensive size.

During closed chain activity, the concave surface of the posterior

facet of the talus will roll and glide in the same direction over the

relatively fixed convex posterior facet of the calcaneus. In the open chain situation, the convex facet of the

calcaneus will roll and glide in opposite directions. The anterior and middle facets are much smaller and together

Figure 41 Subtalar Joint Configuration


form the Anterior Subtalar joint. The Anterior Subtalar Joint is comprised of nearly flat, yet slightly concave facet

at the calcaneus articulating with the slightly convex facets of the talus (Maceira & Monteagudo, 2015).

Ligaments of the Subtalar

Ligament Proximal Attachment

Distal Attachment Function

Calcaneofibular Ligament Lateral Malleolus Calcaneus Limits excessive inversion Tibiocalcaneal fibers of the Deltoid Ligament

Medial Malleolus Sustentaculum Tali of the Calcaneus Limits excessive eversion

Interosseous (talocalcaneal) Ligament

Talar Sulcus Calcaneal Sulcus Bind talus with Calcaneus. Limits the extremes of all motions,

especially inversion Cervical Ligament Inferior-lateral

surface of the neck of the talus

Calcaneal Sulcus (lateral to interosseous ligament attachment)

Bind talus with Calcaneus. Limits the extremes of all motions,

especially inversion Medial Talocalcaneal

Ligament Medial tuberosity of the posterior Talar Process

Talar Shelf Secondary stabilizers of Joint; Blend with capsule

Lateral Talocalcaneal Ligament

Lateral Surface of the Talus

Calcaneal Tarsal Bones Secondary stabilizers of Joint; Blend with capsule

Posterior Talocalcaneal Ligament

Lateral Tubercle of the Talus

Superomedial portion of the Calcaneus Secondary stabilizers of Joint; Blend with capsule


Excessive pronation and supination can contribute to symptom development at the subtalar joint. In

situations with excessive pronation, often referred to as adult acquired flatfoot deformity, signs and symptoms are

typically related to increased medial tensile soft tissue stress and/or increased lateral bony compression (Maceira

& Monteagudo, 2015). Increased medial tensile stress can lead to inflammation of the posterior tibialis, flexor

digitorum longus, and/or flexor halluces longus tendons. Additionally, over-pronation of the subtalar joint can

lead to plantar fasciitis, as the excessive pronation adds additional stress to the plantar fascia. Pain at the sinus

tarsi frequently occurs as a result of lateral bony compression stemming from excessive pronation. At initial

onset, the pain at the sinus tarsi is often due to compression of structures contained in the sinus tarsi (Maceira &

Monteagudo, 2015). Adequate supination is important during the gait cycle for preparing and stabilizing the foot

for the forces impacted upon it during push off. Excessive pronation during the late stance phase, therefore, often

creates difficulties with stabilizing the midfoot at a time when it is necessary. In an act of compensation, the

extrinsic and intrinsic muscles of the foot often become hyperactive in order to reinforce the medial longitudinal

arch, which may eventually lead to muscle fatigue and overuse syndromes throughout the foot and ankle. Further,


68

excessive pronation of the foot can cause atypical stresses

up the kinematic chain to the knee and hip joints,

increasing the risk of developing patellofemoral pain

syndrome.

In cases of excessive supination, signs and

symptoms are typically consequence of increased lateral

tensile soft tissue stress and/or increased medial bony

compression (Maceira & Monteagudo, 2015). Figure 42

gives a visual perspective on how excessive supination can cause atypical stress and pain to bony structures as

well as the plantar fascia. Lateral ankle instability is a common pathology associated with excessive supination,

as the lateral ligaments of the ankle are subjected to constant strain. Tendonitis and tendinopathy of the fibularis

brevis and longus tendons are common presentations of excessive supination. Bony pathologies associated with

excessive supination frequently include stress fractures of the proximal tibia due to increase compression on the

medial aspect of the subtalar joint. As discussed earlier, adequate pronation is necessary during the initial stage of

the gait cycle in order to act as a shock absorber. Over supination, therefore, can cause a chain reaction of stresses

and compensations up the kinematic chain. These compensations and stresses often result in higher risk of

developing patellofemoral pain syndrome or instability of the knee due to the knee being forced to absorb

additional shock at initial contact of the gait cycle. Further, keratosis of the skin often occurs at the fifth

metatarsal (Maceira & Monteagudo, 2015).

Figure 43 Joint Articulations of the Foot

Figure 42 Excessive Supination


Transverse Tarsal Joint (Calcaneocuboid Joint and Talonavicular joint)

Overview

The transverse tarsal joint also known as the midtarsal joint is made up by the calcaneocuboid joint

laterally and talonavicular medially. The transverse tarsal joint is the boundary separating the hindfoot from the

midfoot. These joints are both synovial joints.

The convex head of the talus and concave

surface of navicular forms the talonavicular joint. This

joint congruity allows for significant joint rotation on

medial side of the midfoot. A thin capsule and

ligaments support the joint posteriorly and medially.

The calcaneocuboid joint is a planar, saddle shaped joint formed by the anterior surface of the calcaneus

and the posterior surface of the cuboid. Both joint surfaces have concave and convex parts of their surfaces that

create an interlocking joint that resists sliding and much motion to occur at this joint. A thin capsule also supports

this joint with additional support from ligaments on the dorsal and lateral surfaces.

Neurovasculature. The joints are both innervated by the medial and lateral plantar nerves, branches of

tibial nerve and branches of fibular/fibular nerve on the plantar aspect and deep fibular nerve on the dorsal aspect.

The medial and lateral plantar arteries supply both joints.

Tissue Layers

� Epidermis and dermis � Subcutaneous tissue

o Adipose o Retinaculum (inferior extensor retinaculum)

� Fascia o Crural fascia

� Muscles o Dorsum (lateral to medial)

§ Tendon of fibularis brevis § Muscle of extensor digitorum brevis § Tendon of fibularis tertius § Tendon of extensor digitorum longus

Figure 44 Transverse Tarsal Joint Location


70

§ Tendon of extensor hallucis longus § Tendon of tibialis anterior

o Plantar (lateral to medial) § Plantar aponeurosis § Superficial

• Muscle of abductor digiti minimi • Muscle of flexor digitorum brevis • Muscle of abductor hallucis

§ Second Layer • Muscle of abductor digiti minimi • Muscle of flexor digiti minimi brevis • Muscle of quadratus plantae • Tendon of flexor digitorum longus • Lumbricals • Tendon of flexor hallucis longus

§ Deep Layer • Tendon of fibularis brevis • Tendon of fibularis longus • Tendon of flexor hallucis longus • Tendon of tibialis posterior

� Ligamentous Layer o Long plantar ligament (plantar surface)

� Joint capsule � Synovial membrane � Joint articular surfaces

Joint Motions Joint Motion Primary Muscle(s) Secondary Muscle(s) Eversion Fibularis longus

Fibularis brevis Extensor digitorum longus Fibularis tertius

Inversion Tibialis posterior Tibialis anterior

Extensor hallucis longus Flexor hallucis longus Flexor digitorum longus

Biomechanics

Due to accessory motions of the subtalar joints and other surrounding joints of the foot it is difficult to

measure the amount of specific inversion and eversion coming solely from the transverse tarsal joint. Measured as

a whole, including the subtalar joint, range of motion into eversion is 10-15 degrees and 20-25 degrees of

inversion. Functionally, the transverse tarsal joint works with the subtalar joint in blending all the cardinal planes

mentioned above to produce pronation and supination of the foot.

The closed pack position for the transverse tarsal joint is supination. In supination the joints of the

midfoot and hindfoot twist in opposite directions and arranging planes of motion of the subtalar joint and


transverse tarsal joint to become more perpendicular to one another. This causes the foot to become a rigid lever

allowing for power during push-off during the gait cycle. Open-packed position for the transverse tarsal joint is

midway between extremes of range of motion. In open-packed position the plane of the transverse tarsal joint and

the plane of the subtalar joint become parallel to one another, returning the foot to its loosely articulated

arrangement creating a more flexible foot. The capsular pattern of the joint is dorsiflexion, plantarflexion,

adduction and internal rotation.

During unloaded supination, the tibialis posterior produces a majority of the motion due to its multiple

attachments, including the direct pull of its navicular attachment. Tibialis posterior also has a larger cross

sectional area compared to the other supinator muscles. Pronation is primarily created by the pull of the fibularis

longus elevating the lateral side of the foot and lowering the medial side. This is a primary mover due to a direct

line of pull and large cross sectional area. Eccentric pronation and controlled lowering of the medial longitudinal

arch is provided by the tibialis posterior. Controlled pronation is important during weight bearing and gait so the

foot can have relative flexibility to accommodate uneven walking surfaces. The talonavicular joint is a key pivot

point during these motions. The tibialis posterior pulls up on the concave navicular causing it to spin in its

articulation with the convex head of talus and raise the medial longitudinal arch. The medial longitudinal arch is

an imperative structure for shock absorption during weight bearing and gait. At the rigid calcaneocuboid joint, the

calcaneus inverts and adducts bringing the lateral column of the foot under the medial column, which allows for

the spinning motion of the navicular bone.

To further support the transverse tarsal joint, an irregular shaped capsule as well as ligaments surround

the joint. The spring ligament forms the floor and the medial wall of the talonavicular joint while preventing the

head of the talus from depressing during weight acceptance. The dorsal calcaneocuboid ligament and bifurcated

ligament help to form a strong connection between calcaneous and cuboids. Many other ligaments as seen in the

chart also help provide the stability needed to the transverse tarsal joint.


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Joint Configuration

The transverse tarsal joint seldom moves without concomitant movements of the subtalar joint or other

nearby joints. It is one of the most versatile joints in the foot and moves in an oblique axis that cuts equally

through all three cardinal planes of motion. The primary motions that occur at the transverse tarsal joint about the

anteroposterior longitudinal axis are inversion and eversion of the foot. While inversion and eversion are the

main osteokinematic motions of the transverse tarsal joint, it is referred to as supination and pronation with

regards to arthrokinematic motions along with subtalar joint during gait. The main component of supination is

inversion and the main component of pronation is eversion. Together, the subtalar joint and transverse tarsal joints

make up the majority of pronation and supination that occurs at the foot.

The talonavicular joint on the medial side of the transverse tarsal joint is made up by the articulation of

the convex head of the talus and the concave surface of the navicular bone. This portion of the transverse tarsal

joint resembles a ball and socket joint providing most of the motion of the mid-foot. The motion occurring here is

inversion and eversion.

The calcaneocuboid joint is a saddle-shaped joint made up of both convex and concave surfaces on both

articular surfaces creating a wedge. There is minimal motion occurring at this joint. The purpose of this is to resist

sliding movements and provide stability of the lateral portion of the foot. The movement that does occur at this

joint is about the anteroposterior axis allowing for eversion and inversion of the transverse tarsal joint.

All together the transverse tarsal joint motion of eversion and inversion are accompanied by joint motions

at the subtalar joints that allow for pronation and supination of the ankle and foot. Supination is defined at the

combined movement of inversion, plantarflexion and adduction. Pronation is the combination of eversion,

dorsiflexion and abduction. During these movements the navicular spins within the talonavicular joint. During

open chain supination, the pull of tibialis posterior causes the concave navicular bone to spin around the convex

head of the talus elevating the medial longitudinal arch. With open chain pronation the talonavicular joint is still

the pivot point but the lateral column of foot is elevated above the medial column due to pull of the fibularis

longus muscle.


Ligaments of the Transverse tarsal joint (Calcaneocuboid Joint and Talonavicular joint) Ligament Attachment Action/Resisted Motion

Talonavicular Joint Plantar calcaneonavicular “spring” ligament

Anterior margin of the sustentaculum tali of the calcaneus to the plantar surface of the navicular

Maintains the medial longitudinal arch, connects calcaneus and navicular and supports the head of the talus

Dorsal talonavicualr ligament Talus to dorsal surface of neck of the navicular bone Reinforces the dorsal side of joint Bifurcated ligament Calcaneus to lateral side of the talonavicualr joint Reinforces the dorsal, lateral side of joint Anterior fibers of the deltoid ligament

Talus to the tuberosity of the navicular bone and medial margin of the “spring” ligament

Reinforces the medial side of the joint

Calcaneocuboid Joint Dorsal calcaneocuboid ligament

Medial side of the cuboid to the 1st and 2nd rows of the tarsal bones

Reinforces the dorsal surface of the joint

Long Plantar ligament Plantar surface of the calcaneus, anterior to the calcaneal tuberosity, to the plantar surface of the bases of the lateral 3 or 4 metatarsal bones

Provides stability to the plantar side of the joint

Short Plantar ligament (plantar calcaneocuboid ligament)

Anterior and deep to the long plantar ligament from the plantar surface of the calcaneous to the plantar surface of the cuboid

Provides stability to the lateral side of the foot

Bifurcated ligament Calcaneus to lateral side of the talonavicualr joint Reinforces the dorsal, lateral side of joint


Accessory navicular syndrome. Accessory Navicular Syndrome is a condition where there is an extra

tiny bone located on the medial side of the foot. The extra bone is referred to as an accessory navicular bone. It is

asymptomatic for some people and therefore remains unnoticed throughout their lives. Other people report a

primary symptom of medial foot pain. With this syndrome there can be

aggravation of the posterior tibial tendon or bone and can be cause by

overuse, improper footwear or ankle sprains. For some, there can be a

visible bony prominence on the medial side of foot, while others it can

just be red and swollen. Often this can be treated conservatively with

orthotics or strengthening once the swelling has decreased.

Flat foot deformity/Pes planus. Pes planus is a common pathology of the foot. It can be describes as

both rigid and flexible. The loss of an arch in the foot changes the mechanics of the foot during gait and how the

foot absorbs and transfers loads. Due to these changes, many overuse injuries can occur. One example would be

posterior tibialis tendinitis. Intervention is important and can include the use of orthotics, supportive footwear,

foot intrinsic strengthening, stretching of gastrocnemius/soleus complex and much more.

Figure 45 Accessory Navicular Syndrome


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Pes cavus. Pes cavus is used to describe an abnormally high medial longitudinal arch. Pes cavus tends to

not get as much attention compared to pes planus but can cause issues equally due to changes in mechanics of the

foot during gait. Pes cavus can be described as fixed or progressive and can be considered idiopathic with a strong

genetic correlation. The effect of pes cavus is an increase in pressure placed on metatarsals, which can lead to

metatarsalgia. With more severe cases of pes cavus typically have a known cause such at clubfoot or may be

associated with other neurological diseases. Treatment of pes cavus varies depending on severity. Conservative

management includes stretching of tight muscles and use of orthotics or other specialized footwear. Surgery may

be indicated if it is more severe.

Cuneonavicular joint (Distal intertarsal joint)

Overview

The cuneonavicular joint is classified as a synovial plane joint. This joint is made up of the articulation

between the anterior surface of the navicular and the posterior surfaces of the medial, middle and lateral

cuneiform bones. The navicular bone has three slightly convex facets on the anterior side that articulate with the

concave surfaces of the cuneiform bones. The cuneonavicular joint is one of three joints that make up the distal

intertarsal joints of the midfoot. The other two distal intertarsal joints are the intercuneiform/cuneocuboid

complex and the cuboideonavicular joint. These joints contribute to the medial longitudinal arch of the foot. The

main function of the cuneonavicular joint is to distribute the movements of supination and pronation to the medial

midfoot and forefoot.

Neurovasculature. On the dorsal aspect of the cuneonavicular joint blood supply is from the branching

of the dorsalis pedis artery, the medial and lateral tarsal arteries. The medial plantar artery branch of posterior

tibial artery supplies the plantar aspect of the joint. The innervation of this joint is supplied by the medial and

lateral plantar nerves on the plantar aspect and the deep fibular nerve on the dorsal aspect of the joint.

Tissue Layers

� Epidermis � Dermis � Subcutaneous


o Adipose o Fascia

� Inferior extensor retinaculum on dorsal surface and plantar aponeurosis on ventral surface � Muscles and Tendons

o Ventral surface § Flexor digitorum longus § Flexor hallucis longus § Tibialis posterior § Flexor digitorum brevis § Quadratus plantae

o Dorsal surface § Tibialis anterior § Extensor hallucis longus § Extensor digitorum longus § Extensor hallucis brevis

� Joint capsule/ligaments � Synovial membrane � Joint articular surfaces

Joint Motions Joint Motion* Primary muscles Secondary muscles Supination Tibialis posterior Flexor hallucis longus

Flexor digitorum longus Pronation Fibularis longus (does not cross joint but is the primary influence on pronation of joint) *Only slight gliding occurs at the cuneonavicular joint, as its role is to provide stability for the mid-foot and to absorb and dissipate forces. Joint motions and associated muscles in table below act primarily at the subtalar joint, but in order for pronation and supination to occur the cuneonavicular joint must adjust to transmit pronation and supination forces from the rear-foot to forefoot.

Biomechanics

The cuneonavicular joint helps to provide both stability and adaptability to the mid-foot to allow for

dissipation of stresses from the rear-foot to the forefoot during loading. The cuneonavicular joint plays a small

role in the bigger picture of joint motions occurring at the talocrural, subtalar, and transverse tarsal joints, which

all have unique axes of rotation. The cuneonavicular joint function is to transfer pronation and supination

motions of other joints through the mid-foot. When the component motions are combined to create pronation and

supination they act perpendicular to the oblique axes of rotation. The cuneonavicular joint supports the medial

longitudinal arch of the foot along with the calcaneus, talus and three medial metatarsals. The medial longitudinal

arch provides the main support for the foot during load bearing and helps with shock absorption during impact.

During loading response of the gait cycle, the ankle and foot pronate, achieved by subtalar, transverse

tarsal and distal intertarsal joints, increasing the flexibility of the mid-foot. Although little motion occurs in the

cuneonavicular joint, during pronation there is slight gliding motion of the joint to help with the absorption of


76

forces and increase the flexibility of foot to adjust to a contoured surface. During pronation cuneiforms are

depressed by the body weight and the medial longitudinal arch drops; thus body weight is distributed throughout

foot during early to mid-stance phase. The primary muscle at the cuneonavicular joint that creates pronation is the

fibularis longus. This muscle wraps around the lateral malleolus directing the tendon of the muscle behind the

axis of rotation providing an ideal line of pull to produce plantar flexion and eversion. Tibialis anterior and

posterior attach to the medial side of the foot and also provide eccentric control of the degree of pronation that

occurs at these joints.

The open packed position of the cuneonavicular joint is midway between extremes of pronation and

supination, while closed pack position is during the second half of the stance phase of gait when the foot becomes

supinated. Supination decreases the flexibility of the mid-foot. The primary mover that causes supination of the

ankle/foot is the tibialis posterior. The medial malleolus and flexor retinaculum act as a pulley to tibialis posterior

and flexor digitorum longus to aide with supination. With the help of gastrocnemius and soleus, these muscles act

concentrically to supinate and plantar flex at the subtalar joint which is transmitted through the midfoot via the

cuneonavicular joint. With supination, the medial longitudinal arch rises, creating a rigid lever across the midfoot

to allow for an effective push off phase of gait. Cuneonavicular bony alignment, the cuneonavicular ligaments,

and the plantar fascia support the rigid lever. The tendons of the extrinsic

foot musculature (fibularis longus, tibialis posterior and flexor hallucis

longus) also support the medial longitudinal arch.

Joint Configuration

The cuneonavicular joint is classified as synovial planar and is

enclosed in a common fibrous capsule. The posterior surfaces of the cuneiforms are slightly concave and the

anterior surface of the navicular has three slightly convex surfaces for each cuneiform as shown in Figure 46. Due

to the limited amount of motion that occurs at this joint the arthrokinematic convex-concave relationship does not

apply and is not considered to have a plane of motion or axis of rotation. Slight gliding motion is the only motion

occurring at the cuneonavicular joint to allow for redistribution of forces from rear-foot to forefoot during gait.

Figure 46 Navicular Articular Surfaces


Ligaments of the Cuneonavicular or Distal Intertarsal Ligament Proximal Attachment Distal Attachment Function Other associated constraints of

joint Dorsal cuneonavicular Ligaments

Distal aspect of the dorsal surface of navicular

Dorsum of the corresponding cuneiform

Stabilizes cuneonavicular joint

resists excessive gliding; maintains integrity of medial longitudinal arch

Plantar cuneonavicular Ligaments

1st:Anterior/plantar aspect of the navicular tuberosity 2nd&3rd: Adjacent to the navicular tuberosity on the plantar aspect

1st:Plantar tuberosity of the medial cuneiform 2nd & 3rd: Posterior aspect of the corresponding cuneiform (intermediate and lateral)

Reinforces the joint resists excessive gliding; maintains integrity of medial longitudinal arch

Medial cuneonavicular

Medial aspect of the navicular tuberosity

Medial aspect of the medial cuneiform

Stabilizes cuneonavicular joint

resists shear forces; resists excessive gliding; maintains integrity of medial longitudinal arch

Common Pathology

Navicular fractures. Navicular fractures are the most common type of fracture of the midfoot. The most

common type of navicular fracture is an avulsion fracture occurring at the insertion of the posterior tibial tendon.

Stress fractures of the navicular bone also occur due to overuse, commonly associated with running on hard

surfaces and for long distances. Finally, there can be navicular fractures of the body due to excessive axial

loading. Most navicular fractures are treated conservatively, but this fracture may need to be internally fixated.

Mueller-Weiss Syndrome. While not very common, Mueller-Weiss Syndrome is characterized by

spontaneous osteonecrosis of the navicular bone. This is more common in adult females. This syndrome can cause

chronic deformation of the midfoot with lateral collapse of the navicular and medial protrusion of the talar head.

The syndrome leads to significant deformity, pain and disability.

Koehler’s Disease. Koehler’s disease is a rare condition characterized by avascular necrosis of the

navicular bone in children. It is the childhood version of Mueller-Weiss Syndrome.

Pes planus/cavus. A overstretched plantar fascia or ruptured posterior tibialis tendons can lead to a

dropped medial longitudinal arch leading to pes planus/”flat foot” deformity. Pes planus can also lead to tibialis

posterior strain/tendinitis. Pes planus can affect joints up the chain like the knee and hip. Pes cavus is the

opposite, it is an abnormal high medial longitudinal arch. Pes cavus can cause secondary issues such as plantar

fasciitis or “clawing of toes”.


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Cuboideonavicular Joint

Overview

The cuboideonavicular joint is a very small, fibrous joint that links the lateral and medial aspect of the

transverse tarsal joint. It is part of the distal intertarsal joint complex.

Neurovascular supply. Branches from medial and lateral plantar nerves supply the plantar aspect of the

joint. The deep fibular nerve supplies the dorsal aspect of the joint. The dorsal surface of navicular receives blood

supply from dorsalis pedis, and the plantar surface receives blood from the medial plantar artery. The navicular

also receives blood supply from the posterior tibialis tendon that inserts on its plantar surface. The central portion

of navicular is relatively avascular and therefore at risk for necrosis following an injury to the bone. Cuboid

receives blood from the lateral plantar artery, which arises from the posterior tibial artery.

Tissue Layers Dorsal

• Skin o Epidermis o Dermis

• Inferior extensor retinaculum • Deep dorsal fascia • Dorsal artery and nerve network • Muscles

o Extensor digitorum longus o Fibularis tertius o Tendinous sheath o Extensor digitorum brevis o Extensor hallucis brevis

• Ligaments o Dorsal talonavicular ligament o Bifurcate ligament o Dorsal cuboideonavicular ligament

• Bones o Navicular o Cuboid

Plantar • Skin

o Epidermis o Dermis

• Subcutaneous tissue o Adipose

• Plantar aponeurosis o Medial Plantar Fascia over Navicular


o Lateral Plantar Fascia over Cuboid • Plantar arteries and nerves • Muscles

o Flexor digitorum brevis o Abductor hallucis o Abductor digiti minimi o Flexor digitorum longus tendon o Quadratus plantae o Flexor hallicus brevis o Tibialis posterior tendon

• Ligaments o Long plantar ligament o Plantar Calcaneonavicular (spring) o Short plantar ligament

• Bones o Navicular o Cuboid

Joint Motions Joint Motion* Primary muscles Secondary muscles Supination Tibialis posterior Flexor hallucis longus

Flexor digitorum longus Pronation Fibularis longus (does not cross joint but is the primary influence on pronation of joint) *Minimal gliding occurs to translate supination and pronation across the transverse arch. Most mobility here is secondary to other foot motion.

Biomechanics

The cuboideonavicular may have some gliding and rotation but movement at this joint is very minimal.

The cuboideonavicular, along with the other distal intertarsal joints, transfers supination and pronation

movements across the proximal midfoot.

The primary function of the distal intertarsal group is to create the

transverse arch of the foot, which provides stability to the foot. The distal

intertarsal complex assists in pronation and supination, however, the

kinematics of the midfoot during these movements may not apply to the

cuboideonavicular joint due to its syndesmosis classification and lack of

mobility. The closed pack position for the midfoot is supination and open

pack position is mid-range between supination and pronation.

Figure 47 Plantar Ligaments of Cuboideonavicular

Figure 48 Lateral Ligaments of Cuboideonavicular


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Joint Configuration

The lateral side of the navicular tarsal bone and medial 1/5 of cuboid

form a fibrous joint, rather than the typical synovial joint. The navicular is

convex while the cuboid is concave, however, their articulation does not

exhibit typical arthrokinematics.

Ligaments of the Cuboideonavicular

Ligament Proximal Attachment Distal Attachment Function Other constraints Dorsal ligaments (Figure 48) 1. Dorsal cuboideonavicular 2.Bifurcated 3. Dorsal calcaneonavicular

1. Cuboid 2. Calcaneus (dorsal surface) 3. Calcaneus (dorsal surface)

1.Navicular 2.Navicular (medial branch) and cuboid (lateral branch) 3. Navicular (lateral surface)

-Support and connect tarsal bones with hindfoot -Prevent excess midfoot supination and pronation

Plantar Fascia: Provides primary support to medial longitudinal arch

Plantar ligaments (Figure 49) 1. Plantar cuboideonavicular 2. Plantar calcaneonavicular (spring) 3.Long plantar 4.Short plantar

1. Cuboid (plantar surface) 2. Calcaneus (sustentaculum talus) 3. calcaneus- plantar surface 4. Calcaneous

1. Navicular (plantar

surface) 2. Navicular(plantar

surface) 3. Plantar surface of 3rd,

4th and 5th metatarsals

4. Cuboid-plantar surface

1.Supports the head of talus 2. Supports lateral longitudinal arch 3. Supports longitudinal and transverse arches 4. Same as above

Interosseous ligament

Fibrous ligament that joins the articular surfaces of navicular and cuboid3

Prevents motion at this joint

Common Joint Pathology No known pathology specific to this joint

Intercuneiform and Cuneocuboid Joints

Overview

Three articulations comprise this joint complex: Two between medial, intermediate and lateral

cuneiforms, and one between the lateral cuneiform and cuboid. These joints again act to position the foot in a

proper place by translating hindfoot supination and pronation forces through the midfoot towards the forefoot.

Neurovascular. The cuneiforms as well as cuboid receive innervation from branches of medial and

lateral plantar nerves, and the deep fibular nerve. The cuneiforms and their joints receive blood from medial and

Figure 49 Cuboideonavicular Joint


lateral tarsal arteries, which arise from dorsalis pedis artery, as well as their anastomoses over the dorsal surface

of the foot. The plantar aspect of the cuneiforms receives blood from medial or lateral plantar arteries, branches of

the posterior tibialis artery. Cuboid receives blood from the lateral plantar artery, which arises from the posterior

tibial artery.

Tissue Layers

Dorsal • Skin


• Fascia o Inferior extensor retinaculum o Deep dorsal fascia

• Dorsal artery and nerve network • Muscles and Tendons

o Extensor digitorum longus tendon o Fibularis tertius o Tendinous sheath o Extensor hallucis longus tendon o Extensor digitorum brevis o Extensor hallucis brevis

• Ligamentous layer o Dorsal cuneonavicular ligament o Intercuneiform ligaments o Dorsal cuneocuboid ligaments o Dorsal tarsometatarsal ligaments

• Bones o Medial Cuneiform o Intermediate Cuneiform o Lateral Cuneiform o Cuboid

Plantar • Skin


• Subcutaneous tissue o Adipose

• Fascia o Plantar aponeurosis o Medial and lateral plantar fascia

• Muscles and Tendons 1st Layer o Flexor digitorum brevis o abductor hallucis o abductor digiti minimi

• Plantar arteries and nerves


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• Muscles Deep Layers o Flexor digitorum longus tendon and quadratus plantae o Flexor hallicus brevis o Tibialis posterior tendon

• Ligaments o Long plantar ligament o Plantar calcaneonavicular (spring) o Short plantar ligament

• Bones o Medial Cuneiform o Intermediate Cuneiform o Lateral Cuneiforms o Cuboid

Joint Motions

Joint Motion* Primary muscles Gliding produced during supination/pronation/ plantarflexion/dorsiflexion

Tibialis posterior, flexors, extensors, fibularis longus

*The limited gliding or rotation available at the intercuneiform joints may occur during supination, pronation, dorsiflexion and plantar flexion. In response to an uneven surface the cuneiforms and cuboid may glide past one another as they mold the transverse arch to the given surface, however any motion at these joints

Biomechanics

There is very little motion at these joints, but some sliding movement is available. The intercuneiform and

cuneocuboid complex forms the transverse arch of the foot, which provides stability to the midfoot. During

weight bearing, the transverse arch depresses and allows distribution of body weight across all five metatarsals.

The primary function of the distal intertarsal group is to create the transverse

arch of the foot, which provides stability to the foot. The distal intertarsal complex

assists in producing pronation and supination at the midfoot. During the stance phase of

gait, the hindfoot (subtalar joint) supinates and the midfoot must twist into pronation,

creating a rigid lever for push off. The closed pack position for the midfoot is

supination and open pack position is mid-range between supination and pronation.

Joint Configuration

All three joints in the complex have flat surfaces with synovial, planar joint

articulations that allow some gliding in the horizontal and sagittal planes, but have minimal range of motion. The

planar articulations are parallel with the long axis of the metatarsals.

Figure 50 Cuboideonavicular Complex


Ligaments of the Intercuneiform and Cuneocuboid

Ligament Proximal Attachment

Distal Attachment Function Other associated constraints of joint

Dorsal intercuneiform ligaments

1. Medial cuneiform 2. Intermediate cuneiform 3. Lateral cuneiform

1.Intermediate cuneiform 2. Lateral cuneiform 3. Cuboid

-Support and connect tarsal bones with hindfoot -Prevent excess midfoot supination and pronation

Lateral plantar fascia and plantar aponeurosis: Provides primary support to medial longitudinal arch and supports plantar surface of tarsal bones. The tibialis posterior tendon attaches to the medial and intermediate cuneiforms, and provides support to the cuneiforms on their plantar surface The first metatarsal has one ligament, the second has three, one from each cuneiform, the third metatarsal has one attachment to the lateral cuneiform, the fourth metatarsal has one from cuboid and one from lateral cuneiform, and the fifth metatarsal has one ligament from the cuboid

Plantar intercuneiform ligaments

Same as above, but on plantar surface

Plantar calcaneonavicular (spring)

Calcaneus (sustentaculum talus)

Navicular (plantar surface)

Supports the head of talus and supports lateral longitudinal arch

Long plantar Calcaneus- plantar surface

Plantar surface of 3rd, 4th and 5th metatarsals

Supports longitudinal and transverse arches

Short plantar Calcaneous- plantar surface

Cuboid-plantar surface

Same as above

Dorsal tarsometatarsal ligaments

Dorsal surface of the three cuneiforms

Dorsal aspect of the base of metatarsals 1-5

Stabilizes tarsometatarsal joints


An article by Davies and Saxby discusses intercuneiform instability and states that isolated injuries to

intercuneiform joints are rare. However, an injury to the midfoot, such as damage to any dorsal or plantar

tarsometatarsal or intercuneiform ligament may disrupt the articulations between tarsal bones, leading to gaps

between the cuneiforms. According to Davies and Saxby, this gapping should be recognized as a sign of injury.

Damage to tarsometatarsal ligaments or joints are called Lisfranc injuries, and may impact the integrity of the

intercuneiform joint complex. If a Lisfranc injury presents with concurrent intercuneiform instability, fixation of

the joint may be indicated. Injuries to the Lisfranc joint are also rare. See “Tarsometatarsal Joints” for more on

this injury.

The joint between medial and intermediate cuneiforms can become arthritic. Passive flexion of the first

ray will produce pain in the midfoot if this joint is arthritic. A fusion of the cuneiforms may be indicated.


84

Cuboid subluxation may cause pain or impair arthrokinematics of the cuneocuboid joint. According to a case

study and literature review by Adams and Madden in 2009, most cuboid subluxations often involve plantar and

medial dislocation of the bone, and the incidence of the injury is highest in ballet dancers. The calcaneocuboid

joint is often disrupted by the subluxation, resulting in a widening of the joint space, while the cuneocuboid joint

space narrows due to medial displacement of the cuboid. A patient with this injury usually presents with pain at

the calcaneocuboid joint, but can present with pain at the cuneocuboid joint.

Tarsometatarsal Joints

Overview

The tarsometatarsal joints, frequently called the Lisfranc joints, are joints separating the midfoot from the

forefoot. They articulate the metatarsals to the cuneiforms and cuboid bone to provide a rigid central pillar for

propulsion and strategies to increase foot contact with support during gait. Five joints belong to the grouped

tarsometatarsal (TMT) joints. The first metatarsal articulates

with the medial cuneiform, the second metatarsal with the

intermediate cuneiform, the third with the lateral cuneiform, and

the fourth and fifth metatarsals both articulate with the cuboid

as illustrated in Figure 51. Three joint capsules separate the

TMTs. The first TMT is contained within its own capsule, while the second and third share, and the fourth and

fifth share one.

The second and third TMT joints primarily provide stability for propulsion in gait, while the first, fourth,

and fifth provide more mobility in plantarflexion, dorsiflexion and rotation. As a group the TMT joints provide

stability and mobility where necessary to achieve normalized gait despite hindfoot restriction. When a Lisfranc

injury occurs, it is usually the result of ligamentous damage from excessive force localized over the forefoot and

midfoot junction. Mobility occurring at the Lisfranc joints is usually a result of a restriction in mobility in the

hindfoot and/or tarsometatarsal joints.

Figure 51 Articulation of Tarsals and Metatarsals


Neurovasculature. The neurovascular supply to the joint is provided by the superficial branch of the

fibular nerve for the median TMT joints, the deep fibular sends information of the medial TMT joints and the

sural nerve gives information from the lateral TMT joints. Arterial blood supply to these joints is provided

through the arcuate and lateral tarsal arteries on the dorsal side and the deep plantar arch on the plantar side.

Penetrating branches of these arteries give specific joints their blood supply including the posterior perforating

branches and the plantar metatarsal arteries from the deep plantar arch and the dorsal metatarsal arteries from the

arcuate artery.



• Subcutaneous Fascia • Subcutaneous Tissue

o Neurovascular Supply o Loose Connective Tissue

• Extensor Tendons o Tendons of tibialis anterior, extensor hallucis longus, extensor digitorum longus, fibularis longus,

and tertius o Extensor digitorum brevis o Dorsal interossei mm.

• Neurovasculature o Anterior tibial artery o Deep fibular artery o Medial tarsal artery o Lateral tarsal artery o Dorsal artery of the foot o Deep fibular nerve o Saphenous nerve o Sural nerve

• Joint o Joint Capsule o Dorsal tarsometatarsal ligament o Plantar tarsometatarsal ligament o Interosseous tarsometatarsal ligament o Synovial Fluid

• Bones o Medial Cuneiform o Intermediate Cuneiform o Lateral Cuneiform o Cuboid o 1st metatarsal


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o 2nd metatarsal o 3rd metatarsal o 4th metatarsal o 5th metatarsal

• Plantar surface muscles fourth layer o Plantar interossei

• Plantar surface muscles third layer o Adductor hallucis (oblique head) o Flexor hallucis brevis o Flexor digiti minimi o Fibularis longus tendon o Tibialis posterior tendon

• Plantar surface muscles second layer o Flexor digitorum longus tendon o Quadratus plantae mm. o Flexor hallucis longus tendon o Lumbricals mm.

• Plantar surface muscles first layer (superficial) o Abductor digiti minimi mm. o Flexor digitorum brevis mm. o Abductor hallucis mm.

• Plantar aponeurosis

Joint Motions

Joint Joint Motion Primary Movers Secondary Movers 1st TMT Plantarflexion, Eversion, Abduction Gravity, GRF, JRF Fibularis Longus mm. 1st TMT Dorsiflexion, Inversion, Adduction GRF N/A 4th/5th TMT Plantarflexion, Inversion, Adduction Gravity N/A 4th/5th TMT Dorsiflexion, Eversion, Abduction GRF N/A

Biomechanics

The five TMT joints join the midfoot and forefoot together with varying degrees of mobility. Their main

function is to transmit force from the hindfoot through the forefoot during gait and weight bearing activities. They

provide additional mobility when hindfoot and transverse tarsal motion in inadequate for maintaining forefoot

contact with a support surface in weight bearing. As such, each joint has variable roles and joint motions to

provide the stability or mobility necessary at that portion of the foot.

At the first TMT joint mobility is key to allow compression of the medial longitudinal arch during early

stance phase, followed by raising the medial longitudinal arch during push off. The first TMT joint has the most

mobility of the five joints and incorporates more rotation than the other TMTs. As opposed to the typical foot and

ankle combinations of dorsiflexion/eversion and plantarflexion/inversion, the first tarsometatarsal joint has


coupled motion of plantarflexion/eversion/abduction and dorsiflexion/inversion/adduction. Five degrees of

dorsiflexion is achieved at the first TMT during gait as body weight pushes the cuneiforms towards the supporting

surface, while the supporting surface pushes the first ray up. This corresponds to the lowering of the medial arch

during early and mid stance of gait.

During late stance phase of gait the first TMT joint achieves five degrees of

rapid plantarflexion in part due to activity of the fibularis longus tendon (Figure

52). This functionally shortens the medial arch, allowing propulsion of the hindfoot

off of the ground and maintaining stability of the medial arch during a phase of

gait with increased loads on the midfoot and forefoot.

The second TMT joint is the least mobile because of its anatomical position wedged in between the

intermediate and lateral cuneiform at its base. The third TMT joint is also highly immobile due to its anatomical

position in the center of the midfoot. The second and third TMT joints act as longitudinal stabilizers for the mid

and forefoot.

The fourth and fifth TMT joints provide increased lateral mobility, primarily in plantarflexion,

dorsiflexion, and rotation. During push off as the heel comes off the ground, the fourth and fifth TMT joints invert

about a longitudinal axis to maintain contact with the ground for stability. Increased plantarflexion occurs during

push off at the fifth tarsometatarsal joint (4-12 degrees) compared to the third tarsometatarsal joint (1-2 degrees).

The lateral metatarsals must rotate more to maintain contact with the ground due to their shorter length than their

medial counterparts (Scott, 1993).

The TMT joints work interdependently to allow hollowing and flattening of the plantar surface of the

foot. In weight bearing this is evidenced by the TMT joint attempt to regulate position of the metatarsal heads and

phalanges on the weight-bearing surface to allow proper transverse tarsal movement. Transverse tarsal joints

should account for a majority of weight acceptance from the hindfoot. The TMT joints should not require much

range of motion assuming the hindfoot and forefoot have adequate range. The TMTs primarily function to adjust

Figure 52 Fibularis Longus Contribution to TMT Function


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metatarsal position in weight bearing when transverse tarsal mobility is insufficient to account for hindfoot

position. When in unusual circumstances of uneven surfaces or excessive hindfoot range, the TMT joints

accommodate the foot position into further rotation.

The transverse tarsal joint attempts to correct for excessive hindfoot positioning. The TMT joint will then

use its range of motion to provide additional compensation, only if necessary. When the hindfoot is in excessive

pronation in weight bearing, the transverse tarsal joint will undergo a supination twist to maintain forefoot contact

with the support surface. If transverse tarsal joint motion is insufficient to maintain forefoot contact, the first and

second TMT joint will dorsiflex, while the fourth and

fifth TMT joints plantarflex to maintain metatarsal head

contact with the ground. The first and second TMT

dorsiflexion and the fourth and fifth TMT plantarflexion

both contribute to forefoot inversion around the longitudinal axis of the second ray, this is called supination twist.

If the hindfoot is in excessive supination during weight bearing, the transverse tarsal joints will be locked

into a supination position as well. This leaves the TMT joints to make up for the restricted mobility and adapts to

allow forefoot contact with the support surface. The first

and second TMT joints will plantarflex and evert, while

the fourth and fifth TMT joints dorsiflex and evert. The

muscles in contact with the first and second TMTs will actively

plantarflex those rays to maintain contact, while the ground will forcefully push the fourth and fifth metatarsals

into dorsiflexion. This creates a forefoot eversion motion called the pronation twist.

Joint Configuration

The TMT joints are all considered planar joints with little concavity or convexity contributing to their

arthrodial movement. Therefore they do not follow typical concave/convex rules. They do, however, glide a few

degrees in any direction due to ground reaction forces. The distal cuneiforms and cuboid are slightly convex,

articulating with the slightly concave metatarsal bases, although this is controversial. Three columns form the

Figure 53 Supination Twist

Figure 54 Pronation Twist


joint capsules for the TMT joints. The first column consists of the first metatarsal and the medial cuneiform. The

second column consists of the second and third metatarsal and the intermediate and lateral cuneiforms. The third

column consists of the fourth and fifth metatarsals and the cuboid bone.

The TMT joints have unique, although interdependent joint axes. The first and fifth joint axes are

triplanar and the greatest range of motion is allowed at the first TMT joint about an oblique axis of motion. At the

first TMT joint plantarflexion is accompanied by abduction and eversion while dorsiflexion is accompanied by

inversion and adduction. The abduction and adduction components are minimal compared to plantarflexion,

dorsiflexion, inversion, and eversion. The fifth TMT joint has opposite associated motions; plantarflexion is

associated with inversion and adduction, yet dorsiflexion is accompanied by eversion and abduction. These

associated movements within the triplanar configuration allow for pronation and supination twist, especially

during gait on convex surfaces.

The third TMT joint has minimal motion and the joint axis coincides with a coronal axis. Therefore the

third TMT joint primarily acts in the sagittal plane with plantarflexion and dorsiflexion. The second and fourth

TMT joints are oriented in between the coronal axis of the third and the oblique axes of the first and fifth. The

fourth TMT joint moves within the triplanar axis similar to the fifth TMT but with less total range. The second

TMT is wedged in between the medial and lateral cuneiforms and therefore is the least mobile of the five TMTs,

but has a similar axis as the first TMT.

Ligaments of the Tarsometatarsals

Ligament Proximal Attachment Distal Attachment Function Other associated constraints of joint

Deep Transverse Metatarsal

Medial metatarsal heads Lateral metatarsal heads

Prevent splaying of metatarsal heads

Reinforce plantar stability of TMT joints

Dorsal Tarsometatarsal

Dorsal aspect of medial, intermediate, lateral cuneiforms and cuboid

Dorsal aspect of base of metatarsals

Prevent excessive plantarflexion at TMT

Prevent hyperplantarflexion of midfoot over forefoot

Plantar Transverse Metatarsal

Plantar aspect of medial, intermediate, lateral cuneiforms and cuboid

Plantar aspect of base of metatarsals

Prevent excessive dorsiflexion at TMT

Prevent hyperdorsiflexion of midfoot on forefoot.


90


Lisfranc injury. Lisfranc injuries are the most common subset of injuries that occur at the

tarsometatarsal joints. A Lisfranc injury is any injury of these joint complexes and

can include ligamentous disruption, fracture, or dislocation. These are commonly

low energy injuries that occur during sporting activities when a foot lands on an

uneven surface without proper contact. Bruising on the bottom of the foot in the

region of the Lisfranc joints is highly suggestive of Lisfranc injury, but bruising on

the dorsal foot and swelling of the midfoot may accompany as well. Plain

radiographs may show dislocation or disruption of the TMT joint alignment. This

injury results in one or more metatarsal bones being displaced from the tarsus. Most

commonly, these injuries involve the tarsometatarsal joints although occasionally

occur near the intermetatarsal joints as well. These injuries can be classified as direct or indirect. A direct injury

may be the result of a crush injury or a heavy object falling on the midfoot, and an indirect injury can be the result

of a sudden rotational force on a plantar flexed

foot. This injury can often be diagnosed through

the use of X-ray and operative verses non-

operative treatment is determined based on

severity of the injury.

Intermetatarsal Joints

Overview

The bases of the four lateral metatarsals have points of contact between one another, which create three

small synovial joints referred to as intermetatarsal joints. These joints are classified as plane joints due to their

relatively flat articulating surfaces. Plantar, dorsal, and interosseous ligaments span the articulations between the

Figure 55 Mechanism for Lisfranc Injury

Figure 56 Lisfranc Injury Location


bases of the four lateral metatarsals. The deep transverse metatarsal ligaments attach

the distal ends of all five metatarsals. Although interconnected by ligaments, there is

not a true joint that forms between the base of the first and second metatarsals,

resulting in increased movement of the first ray. There is very little individual motion

that occurs at the intermetatarsal joints. Motion that is available at these joints is

primarily a gliding motion and allows for flexibility at the tarsometatarsal joints.

Neurovasculature. The main blood supply to the intermetatarsal joints

comes from the lateral metatarsal artery, which is a branch of the dorsal artery of the foot. Digital nerves innervate

the intermetatarsal joints.



§ Adipose tissue § Loose connective tissue

• Superficial fascia • Deep fascia • Muscles and tendons

o Dorsal surface § Extensor digitorum longus tendon § Extensor digitorum brevis muscle § Extensor hallucis longus tendon § Extensor hallucis brevis muscle

o Plantar surface (from 1st layer à deep) § Plantar aponeurosis § flexor digitorum brevis muscle § abductor hallucis muscle § abductor digiti minimi muscle § quadratus plantae muscle § flexor digitorum longus tendons § flexor hallucis brevis muscle § flexor digiti minimi brevis muscle § adductor hallucis muscle (transverse and oblique heads)

• Nerve o Digital nerves

• Arteries o Lateral metatarsal artery

• Ligaments o Dorsal metatarsal ligaments

Figure 57 Metatarsal Names

Figure 58 Sagittal cut of foot showing tissue layers


92

o Plantar metatarsal ligaments o Interosseous ligaments

• Articular capsule of Intermetatarsal joints o Outer fibrous layer of capsule o Inner synovial membrane of capsule o Articular cartilage covering surface of metatarsal bases 2-5 o Metatarsal bases articulating surfaces

Joint Motions Joint Motion Primary Movers Secondary Movers

Gliding motion: to enhance motion at the tarsometatarsal joint

There are no primary movers at the intermetatarsal joint independently.

Muscles that act on the tarsometatarsal joint are also responsible for gliding motion that occurs at the intermetatarsal joint There are no muscles that attach to the intermetatarsal joints specifically

Biomechanics

Overall, there is very little information about the biomechanics of the intermetatarsal joints individually

due to the limited motion available in the joint and the joints overall function of stability.

The intermetatarsal joints overall assist in stability of foot complex. There are three main ligaments that

interconnect the bases of the metatarsals and one ligament that interconnects the distal ends of the metatarsals.

These ligaments include: plantar metatarsal ligaments, dorsal metatarsal ligaments, interosseous metatarsal

ligaments, and the deep transverse metatarsal ligament. Together, these ligaments bind each metatarsal to one

another, limit the motion available to only gliding motions and assist to create a stable foot. Muscles that have

function in the foot do not directly act on the intermetatarsal joints for individual specific motion. The muscles

that act on the tarsometatarsal joints are the same that act on the intermetatarsal joints and will be discussed with

discussion of the biomechanics of

the tarsometatarsal joint. The closed

packed position for the

intermetatarsal joints is supination

of the foot and open pack position

of the intermetatarsal joints is

pronation of the foot.

Figure 59 Close relation of joints in foot. Intermetatarsals contribute to stability


Joint Configuration

The intermetatarsal joints are formed by the articulation of the bases of metatarsals 2-5. Although

ligaments also interconnect the 1st metatarsal; it is stated that a true joint does not form between the first and

second metatarsals. The lack of articulation and joint formation between the 1st and 2nd metatarsal, increases the

movement available at the first ray. The intermetatarsal joints are classified as plane joints. The definition of a

plane joint is a synovial joint that only allows gliding movements in the plane of articular surfaces. Due to the

relative flat articulations of the intermetatarsal joints, these joints do not follow the concave or convex rule. There

is very little motion that occurs among these joints. Most motion that does occur, occurs at the tarsal end of the

metatarsals. This motion is limited to anterior and posterior gliding motions of the articular surfaces among one

another. Anterior and posterior gliding occurs around a coronal axis in the sagittal plane. This gliding motion

allows for flexibility at the tarsometatarsal joints.

Ligaments of the Intermetatarsal Joints


Plantar Metatarsal Ligament

Plantar surfaces of the medial bases of the metatarsals

Plantar surfaces of the lateral bases of the metatarsals

-binds metatarsals to one another

Dorsal Metatarsal Ligament

Dorsal surfaces of the medial bases of the metatarsals

Dorsal surfaces of the lateral bases of the metatarsals

-limits motion available at the intermetatarsal joint, allowing only gliding motion amount the joints

Interosseous Metatarsal Ligament

Medial surfaces of the bases of the metatarsals

Lateral surfaces of the bases of the metatarsals

-assists to stabilize the foot

Deep Transverse Metatarsal Ligament

Spans the distal surface of metatarsal bones

Heads of metatarsal bones


Intermetatarsal neuroma. This type of injury is also referred to as Morton’s neuroma and is caused by

the compression of a nerve between two metatarsal heads. The most common nerve to be involved is the third

common digital nerve, which is the main intervention to the intermetatarsal joint. Degenerative neuropathy and

the formation of edema and fibrotic nodules around the nerve result from increased pressure on a nerve for a


94

prolonged period of time. Activities that increase weight bearing and compressive pressure in the forefoot can

trigger signs and symptoms of intermetatarsal neuroma to form. Common symptoms include pain along the

anterior transverse arch that may radiate into the toes, pain on the plantar aspect of the foot, which can radiate up

into the ankle and lower leg, and possible tingling or numbness. Also, increase in intermetatarsal pressure and

pain during weight bearing and donning of tight-fitting shoes. Usually a patient will state symptoms to be relieved

when no longer weight bearing or with the removal of shoe wear. Mulder's sign can be used to test for

intermetatarsal neuromas and also the patient will have point tenderness to the area with the neuroma. A positive

diagnosis is made with presentation of clinical symptoms in combination with

imaging. Some initial treatment options include shoe modification, orthotics

or a corticosteroid injection. For more severe neuromas, a surgical excision of

the neuroma may need to take place although there is the risk of a stump

neuroma where the neuroma may return.

Jones fracture. The fifth metatarsal is the most common metatarsal to

be fractured; this is referred to as a Jones fracture. This injury is most commonly seen as the metaphyseal-

diaphyseal junction. The mechanism of injury is usually excess stress placed across the metatarsal when the heel

is off the ground and the forefoot is planted. This type of injury can also be the

result of an old stress fracture progressing to a complete fracture. Blood supply

to the fifth metatarsal is less than adequate in this area, which can impact the

healing of the injury. Treatment options may vary based on the mechanism of

injury and the severity of the injury. Other injuries that can occur at the base of

the fifth metatarsal include a stress fracture, or an avulsion fracture.

Figure 60 Morton's Neuroma between 3rd and 4th metatarsals

Figure 61 Base of 5th metatarsal affected by multiple fracture types


Metatarsophalangeal Joint (MTP joints)

Overview

The 5 metatarsophalangeal (MTP) joints of the foot are formed by the articulation between the head of the

5 metatarsals and the corresponding proximal end of each proximal phalanx. The MTP joints are condyloid

synovial joints with separate joint capsules enclosing each joint.

Neurovasculature. The MTP joints receive their blood supply from the lateral metatarsal artery, which is

a branch of the dorsalis pedis artery and are innervated by the digital nerves. The MTP joints are important during

the gait cycle via their roles in creating the Windlass effect to create a rigid lever for push off and for extending

enough to allow for rapid plantar flexion and heel rise.



• Subcutaneous Fascia • Subcutaneous Tissue

o Neurovascular Supply o Loose Connective Tissue

• Extensor Tendons o Tendons of tibialis anterior, extensor hallucis longus, extensor digitorum longus, fibularis longus,

and tertius o Extensor digitorum brevis o Dorsal interossei mm.

• Neurovasculature o Anterior tibial artery o Deep fibular artery o Medial tarsal artery o Lateral tarsal artery o Dorsal artery of the foot o Deep fibular nerve o Saphenous nerve o Sural nerve

• Joint o Joint Capsule o Dorsal tarsometatarsal ligament o Plantar tarsometatarsal ligament o Interosseous tarsometatarsal ligament o Synovial Fluid

• Bones


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o Medial Cuneiform o Intermediate Cuneiform o Lateral Cuneiform o Cuboid o 1st metatarsal o 2nd metatarsal o 3rd metatarsal o 4th metatarsal o 5th metatarsal

• Plantar surface muscles fourth layer o Plantar interossei

• Plantar surface muscles third layer o Adductor hallucis (oblique head) o Flexor hallucis brevis o Flexor digiti minimi o Fibularis longus tendon o Tibialis posterior tendon

• Plantar surface muscles second layer o Flexor digitorum longus tendon o Quadratus plantae mm. o Flexor hallucis longus tendon o Lumbricals mm.

• Plantar surface muscles first layer (superficial) o Abductor digiti minimi mm. o Flexor digitorum brevis mm. o Abductor hallucis mm.

• Plantar aponeurosis

Joint Motions

Joint Motion Primary Movers Secondary Movers 1st MTP Extension Extensor Hallucis Brevis Flexor Hallucis Longus 2-5th MTP Extension Extensor Digitorum Brevis Extensor Digitorum Longus 1st MTP Flexion Flexor Hallucis Brevis Abductor Hallucis 2-5th MTP Flexion Flexor Digitorum Brevis Flexor Digitorum Longus, Quadratus Plantae, Plantar interossei 3-5, Lumbricals 5th MTP Flexion Flexor digiti minimi Abductor Digiti Minimi 1st MTP Abduction Abductor Hallucis 2nd-4th MTP Abduction Dorsal interossei 5th MTP Abduction Abductor digiti minimi 1st MTP Adduction Adductor Hallucis 3rd-5th MTP Adduction Plantar interossei

Biomechanics

The metatarsophalangeal joints demonstrate movement in two degrees of freedom. Movement occurs in

the transverse plane and sagittal planes, extension and flexion occurring in the sagittal plane, and abduction and

adduction occurring in the transverse plane. In describing motion, the second digit serves as the reference digit

for naming adduction and abduction in the toes, which differs from the reference system of the hand being the 3rd


digit. The axes of rotation for all voluntary motions of the MTP joints are through the center of each metatarsal

head. From neutral the toes can be extended to 65 degrees and flexed 30 to 40 degrees. The great toe; however,

allows approximately 85 degrees of extension. During mid to late

stance, the MTP joints extend, and through the windlass effect,

raise the medial longitudinal arch and stabilize the midfoot and

forefoot for push off as demonstrated in Figure 62. This action at

the MTP joint is crucial for creating the rigid lever effect of the

foot during push off, thus preparing and protecting the foot from

the great amount of force during push off. A common problem

presented in clinic is foot and lower extremity pain due to wearing

flip-flop sandals. A common walking strategy while wearing flip-flops is to flex the MTP joints, particularly the

great toe, in order keep the flip flop on the foot. Because of this lack of extension of the Hallux, the Windlass

effect is muted and the plantar fascia does not rise adequately in order to act as a shock absorber during initial

contact and the early phase of gait, causing symptoms in the foot and lower extremity.

Joint Configuration

The head of each metatarsal is convex, which articulates with the shallow concave surface of the proximal

end of each proximal phalanx. In closed chain motion, as demonstrated in walking, the convex surface of the

metatarsal head will roll and glide in opposite directions over the relatively fixed concave surface of the proximal

phalanx. In open chain motion, the concave surface of the phalanx moves on the convex surface of the metatarsal

head, meaning that the roll and glide motion will be in the same direction. The transverse metatarsal ligaments

blend with and join the plantar plates of one MTP joint to its adjacent MTP joint. By connecting all five plates,

the transverse metatarsal ligaments maintain some similarities in planar motion between the first ray and the

lesser rays, thereby suiting the foot for weight bearing and propulsion. This differs from the hand, which is suited

for manipulation and opposition because the MTP joints can move independently of the thumb.

Figure 62 Medial Longitudinal Arch


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Ligaments of the Metatarsophalangeal

Ligament Proximal Attachment Distal Attachment Function Collateral ligaments Posterior tubercle

metatarsal head Plantar Plate on plantar aspect and Sesamoid

Bones Support capsule on each side

Transverse metatarsal ligaments

Metatarsal head (1-5)

Plantar Plates of Transverse Metatarsal Ligaments 1-5

Associates motion between the 5 MTP joints


Hallux limitus. Hallux limitus is a posttraumatic condition, frequently caused by forced hyperextension

of the metatarsophalangeal joint of the great toe. It is characterized by gradual limitation of motion, pain at the

metatarsophalangeal joint of the great toe, and articular degeneration. Hallux limitus is diagnosed, regardless of

mechanism of injury, by the clinical presentation of great toe extension limited to 55 degrees or less as well as

pain at the metatarsophalangeal joint. Hallux limitus can have a significant affect on the mechanics of walking, as

65 degrees of great toe extension is typically needed during heel rise in the late stance phase of the gait cycle. To

avoid pain, a person with hallux limitus will often alter their gait pattern, frequently walking on the lateral surface

of the affected foot. Addressing pain, joint mobility, and gait training are all important aspects of treatment for

hallux limitus.

Hallux valgus. Hallux valgus, commonly referred to as a bunion, is typically associated with adduction

of the first metatarsal towards the midline of the body about the tarsometatarsal

joint. The adducted position of the first metatarsal can lead to lateral dislocation

of the metatarsophalangeal joint. It is this dislocation of the joint that can lead to

the complete exposure of the first metatarsal head as a “bunion”. In some cases,

the deviation is so great that the 1st toe overlaps the second toe. In this case the

1st toe cannot be moved away from the 2nd digit because the sesamoid bones,

which typically lie under the head of the first metatarsal, displace and migrate to

the space between the heads of the 1st and 2nd metatarsals. While hallux valgus is

often thought of as pathology of only the great toe, it is actually a pathology that affects the entire first ray.

According to a study by Lee et al., there is a strong correlation between the hallux valgus angle, illustrated in

Figure 63, and development of osteoarthritis of the second MTP joint. Additionally, the study found that as the

Figure 63 Hallux Valgus


intermetatarsal angle, also illustrated in Figure 63, between the first and second digit increases, the likelihood of

developing OA in the second MTP joint increased as well.

Interphalangeal Joints

Overview

There are nine interphalangeal joints, five proximal and four distal. All interphalangeal joints are similar

and differences will be discussed if needed. The articulations

of the proximal interphalangeal joint (PIP) are made up of the

heads of the proximal phalanges and the bases of the middle

phalanges. The articular surfaces of the distal interphalangeal

joints (DIP) are made up of the head of the middle phalanges

and the bases of the distal phalanges. The reason for one less

DIP compared to PIP is there is no middle phalange in the first

toe. The interphalangeal joints are characterized as synovial hinges joints. A hinge joint has only one degree a

freedom. The interphalangeal joints move within the sagittal plane about the horizontal axis allowing for the

primary motion of flexion and extension. A joint capsule, collateral and plantar ligaments reinforce each

interphalangeal joint.

Neurovasculature. The interphalangeal joints are innervated by the digital nerves and receive blood

supply from the digital branches of the plantar arch.

Tissue Layers � Epidermis � Dermis � Hypodermis � Fascia (superficial and deep) � Adipose tissue � Dorsal:

o Extensor digitorum Longus tendon (digits 2-5) o Extensor Digitorum brevis tendons (digits 2-4) o Extensor Hallucis Longus tendon o Extensor Hallucis brevis tendon

� Plantar:

Figure 64 Bones of forefoot


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o Plantar aponeurosis o Flexor Digitorum Brevis Tendons o Flexor hallucis longus tendon o Flexor digitorum Longus tendons

� Joint Capsule � Synovial membrane � Synovial fluid � Articular cartilage � Pereosteum � Bone

o Heads of the proximal phalanges o Bases of middle phalanges o Heads of middle phalanges o Bases of distal phalanges

� Ligament o Collateral ligaments o Plantar ligaments (plantar surface)

Joint Motions Joint Motion Primary Movers Secondary Movers Flexion Flexor hallucis longus, flexor digitorum longus, flexor

digitorum brevis Flexor Hallucis Brevis, Flexor digiti minimi, Quadratus plantae, lumbricals

Extension Extensor hallucis longus, extensor digitorum longus, extensor digitorum brevis

NA

Biomechanics

Motions that occur at these joints are flexion and extension. The closed pack position is in full extension

and open packed position is in slight flexion. The capsular pattern for the interphalangeal joints is more limitation

of flexion than extension. The interphalangeal joints relaxed position is in slight flexion.

The proximal interphalangeal joints flexion range of motion is 35 degrees whereas the distal

interphalangeal joints flexion range of motion is 60 degrees. The flexion range of the interphalangeal joint of the

first digit is 90 degrees. The primary flexor with the greatest cross-sectional area, direct line of pull and greatest

moment arm of digits 2-5 is flexor digitorum longus, which attaches to the distal phalanx. Flexion of digits 2-5 is

also completed by flexor digitorum brevis but it does not cross the distal interphalangeal joint. This is a similar

relationship to the extensor digitorum longus and brevis on the dorsal surface of the foot.

The proximal interphalangeal joints (2-5) have 0 degrees of extension and the distal interphalangeal joints

have 30 degrees of extension. The primary extensor of the IP joints is the extensor digitorum longus because it

has the greatest cross-sectional area, direct line of pull and greatest moment arm. Extensor digitorum brevis is a


primary extensor due to its direct line of pull but its moment arm is shorter and has a smaller cross sectional area.

Similar to the flexors, extensor digitorum longus only crosses the distal interphalangeal joint.

The primary muscle responsible for flexion of interphalangeal joint of the hallux is flexor hallucis

longus and the primary extensor in extensor hallucis longus. They are both primary movers due to their direct line

of pull. The collateral and plantar ligaments both provide joint stability in addition to the joint capsules. The

collateral ligaments restrict medial and lateral translation.

Joint Configuration

Interphalangeal joints only have one degree of freedom acting about the sagittal plane of motion about the

medial-lateral axis. The articulations of the proximal interphalangeal joint (PIP) are made up of the heads of the

proximal phalanges and the bases of the middle phalanges. The articular surfaces of the distal interphalangeal

joints (DIP) are made up of the head of the middle phalanges and the bases of the distal phalanges. The concave

bases of the middle and distal phalanges move on the convex heads of the proximal and middle phalanges,

therefore roll and glide will occur in the same direction. During extension, the bases of the proximal and middle

phalanges roll and glide in the dorsal direction. With flexion, bases of middle and distal phalanges roll and glide

in the plantar direction.

Ligaments of the Interphalangeals Ligament Proximal Attachment Distal Attachment Function Other constraints Plantar Ligaments

Plantar, medial surfaces of the interphalangeal joints

Plantar, lateral surfaces of the interphalangeal joints

Support plantar aspects of joint capsules

NA

Collateral Ligaments

Both the medial and lateral aspects of the heads of the proximal and middle phalanges

Both the medial and lateral aspects of the bases of the middle and distal phalanges

Support joint capsules on each side

Prevents lateral and medial translation of the phalanges

Common Pathology

Hammertoe. Hammertoe is a condition of the proximal

interphalangeal joints in an abnormal flexion posture and

metatarsophalangeal joints and distal interphalangeal joints in an

Figure 65 Hammertoe


102

abnormal extension posture. Any toe can be affected and it is common to have more than one. Hammertoes can be

defined as flexible or rigid

Fractures. Fractures of phalanges can occur. One can have non-displaces fractures, which are treated

conservatively with tape or one can have displaced fractures that are treated with surgery.

Dislocations. Dislocation is among the most common injury to the interphalangeal joints. This most

commonly occurs with the hallux. The mechanism of injury involves axial loading with stubbing or jamming the

toe. Commonly the distal phalanx gets displaced dorsally. Surgical intervention is rare.


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Final le arthrology guide table 25

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