© 2009 McGraw-Hill Higher Education. All rights reserved. Chapter 9: Mechanisms and Characteristics...

© 2009 McGraw-Hill Higher Education. All rights reserved.

Chapter 9: Mechanisms and Characteristics of

Musculoskeletal and Nerve Trauma


What is one of the main roles of an Athletic Trainer?

Recognizing a specific injury to a musculoskeletal or nerve structure and the mechanical forces that produce that trauma.

Trauma: a physical injury or wound produced by an external or internal force.


Tissue Properties– Load

• An external force acting on the body causing internal reactions within the tissues

– Stiffness • Ability of a tissue to resist a load• Greater stiffness = greater magnitude load can resist

– Stress • Internal resistance to a load

– Strain• Internal change in tissue (i.e. length) resulting in deformation (change)



Tissue Properties continued• Elasticity: Property that allows tissue to return to normal after

deformation

• Yield point: when tissue is deformed to the extent that is not longer reacts elasticity

• Plastic: when a load is removed, deformation of the tissue to an extent remains

• Creep: Deformation of a tissue over a period of time

• Mechanical Failure: exceeding the ability of the tissue to withstand the load and the tissue breaks down


Figure 9-1


With this basic knowledge, explain an ankle sprain.

• There is a load on the ankle causing stress and strain to the ligaments of the ankle. This causes deformation of the ligament due to the fact that the ligaments are plastic. Depending on the load the ligament may hit its yield point and cause mechanical failure.


• Tissue Loading– Tension (Figure B)

• Force that pulls and stretches tissue

– Compression (Figure A)• Force that results in tissue crush – two forces

applied towards one another

– Shearing (Figure C)• Force that moves across the parallel organization of

tissue


– Bending (Figure D)• Two force pairs act at opposite

ends of a structure (4 points)• Three forces cause bending (3

points)• Already bowed structures

encounter axial loading

– Torsion (Figure E)• Loads caused by twisting in

opposite directions from opposite ends

• Shear stress encountered will be perpendicular and parallel to the loads

Figure 9-2 D & E


What are the 5 types of loads?Draw each of the loads.

• Compression

• Tension

• Shearing

• Bending

• Torsion


Traumatic vs. Overuse InjuriesAcute vs. Chronic

• Debate over acute vs. chronic injuries– When injury is acute – something has initiated

the injury process (usually sudden)– Injury becomes chronic when it doesn’t

properly heal (over a period of time)

• Could define relative to mechanism– Traumatic (i.e. a direct blow) vs. Overuse (i.e.

repetitive dynamic use over time)


Classification and Load Characteristics of Injuries

1. Go to page 241 and pick an injury.

2. Define the injury.

3. Classify it (overuse or traumatic)

4. Explain the mechanism of the injury or load.


Musculotendinous Injuries and the Anatomy

• Musculotendinous Unit:– Muscle: contractile cells or fibers that produce

movement; in athletics skeletal or striated muscle fibers are the most common injured

– Tendon: thicker part of muscle that connects the muscle to the bone; resilient to injury

– Fascia: Fibrous covering over the muscle


Skeletal Muscle

Figure 9-3


• Muscle Strains– Stretch, tear or rip to muscle or its tendon– Cause is often:

• Abnormal muscle contraction is the result of:

1)failure in reciprocal coordination of agonist and antagonist

2) electrolyte imbalance due to profuse sweating

3) strength imbalance


– Muscle Strain Grades• Grade I - some fibers have been stretched or actually

torn resulting in tenderness and pain on active ROM, movement painful but full range present

• Grade II - number of fibers have been torn and active contraction is painful, usually a depression or divot is palpable, some swelling and discoloration result

• Grade III- Complete rupture of muscle or musculotendinous junction, significant impairment, with initially a great deal of pain that diminishes due to nerve damage


Rehabilitation

– Time required for healing may be lengthy– Often involves large, force-producing muscles– Treatment and recovery may take 6-8 weeks

depending on severity– Return to play too soon could result in re-injury


Figure 9-4


Name the Three Grades of Muscle Strains and Define Each.

• Grade I: muscle fibers stretched and slightly torn; Some tenderness but minor main with Full ROM

• Grade II: Some muscle fibers have been torn; Active contraction painful; Divot with palpation; some swelling and discoloration; ROM is decreased

• Grade III: complete rupture of the muscle; No Active ROM or very limited; Pain is intense and then quickly diminishes


• Muscle Cramps– Painful involuntary skeletal muscle contraction

– Can coincide with heat cramps due to excessive water loss or electrolytes

• Muscle Guarding– Involuntary muscle contraction in response to

pain following injury• The muscles that surround the injured area

contract or splint the area


• Muscle Spasms– A reflex reaction caused by trauma

– Two types• Clonic - alternating involuntary muscular contractions

and relaxations in quick succession

• Tonic - rigid contraction that lasts a period of time

– May lead to muscle or tendon injuries


• Muscle Soreness: pain caused by overexertion in exercise

– Generally occurs following participation in activity that individual is unaccustomed

– Two types of soreness1) Acute-onset muscle soreness - accompanies fatigue, and is

pain experienced immediately after exercise

2) Delayed-onset muscle soreness (DOMS) - pain that occurs 24-48 hours following activity that gradually subsides (pain free 3-4 days later)– Potentially caused by slight microtrauma to muscle or

connective tissue structures, eccentric or isometric contractions

– Prevent soreness through gradual build-up of intensity


Review:

1. What are muscle cramps?

2. What are the two types of muscle spasms?

3. What does DOMS stand for?


• Tendon Injuries- connects muscle to bone– Can produce and maintain 8,700- 18,000 lbs/in2

– Collagen straightens during loading but will return to shape after loading

– Breaking point occurs at 6-8% of increased length

– Tears generally occur in muscle and not tendon


• Tendinitis: inflammation of the tendon– Mechanism: Gradual onset, due to

microtrauma of the tendon respectively becomes irritated

– Signs/ Symptoms: Swelling, pain, warmth, and crepitus (crackling feeling or sound)

– Management: Key to treatment is rest (substitute an activity)

A: Normal B: Inflammed

© 2008 McGraw-Hill Higher Education. All rights reserved.© 2008 McGraw-Hill Higher Education. All rights reserved.


Tendonosis: Without proper healing tendinitis may begin to degenerate

• Signs and Symptoms: Less inflammation, pain with movement or touching, stiffness and restricted motion

• Management: Stretching and strengthening


• Tenosynovitis– Inflammation of the tendon and the synovial sheath– Acute case: rapid onset, crepitus, and diffuse

swelling– Chronic cases: result in thickening of tendon with

pain and crepitus• Often occurs in long flexor tendon of the digits and the

biceps tendon

– Due to nature of injury anti-inflammatory agents may be helpful (NSAIDs)


• Myofascial Trigger Points– Discrete, hypersensitive nodule within tight band of

muscle or fascia (knots)– Classified as latent or active– Latent trigger point

• Does not cause spontaneous pain, May restrict movement or cause muscle weakness, Become aware of presence when pressure is applied

Active trigger point• Causes pain at rest, Applying pressure = pain = jump sign,

Tender to palpation with referred pain, Found most commonly in muscles involved in postural support


LAB: Finding Trigger Points


• Contusions: AKA bruise; compression of soft tissue that results in bleeding into surrounding area– Mechanism: Result of sudden blow to body, Can be both

deep and superficial– Signs and Symptoms: ecchymosis (bluish- purple

discoloration of the skin), pain with palpation and movement

– Myositis ossificans: Chronically inflamed and contused tissue may result in generation of calcium deposits, bone spurs in the muscle

• Prevention through protection with padding


• Atrophy and Contracture– Atrophy: wasting away of muscle due to

immobilization, inactivity, or loss of nerve functioning, muscle decreasing or weakening

– Contracture is an abnormal shortening of muscle where there is a great deal of resistance to passive stretch usually due to scar tissue


Part II


Synovial Joints Injuries• 2 or more bones the articulate (move) with one

another to allow motion in one or more places

• Additional synovial joint characteristics– Joint Capsule and ligaments (connect bone to bone) for

support– Capsule is lined with synovial membrane (lubrication,

shock absorption and nutrition)– Hyaline or articular cartilage– Blood and nerve supply with muscles crossing joint


Ligament Sprains– When a stress or load is applied to the joint and forces motion

beyond its normal limit, injury to the ligament is likely – Graded based on the severity of injury

• Grade I – some stretching of fibers, minimal instability, mild to moderate pain, localized swelling and joint stiffness

• Grade II – some tearing and seperation of the fibers, moderate instability, moderate to sever pain and swelling

• Grade III – total tear of the ligament which leads to severe instability, severe to no pain, severe swelling, may have subluxation (joint slides out of place)


• Can result in joint effusion and swelling, local temperature increase, pain and point tenderness, ecchymosis (change in skin color) and possibly an avulsion fracture (pulling away from the bony structure)

• Greatest difficulty with grade 1 & 2 sprains is restoring stability due to stretched tissue and inelastic scar tissue which forms

• To regain joint stability strengthening of muscles around the joint is critical

What are the 3 Grades of Sprains and Describe them?

• Grade I: Some stretching, minimal instability, mild to moderate pain, localized swelling

• Grade II: Some tearing and stretching, moderate instability, moderate to severe pain, moderate to severe swelling

• Grade III: Total tear, instable, severe then no pain, severe swelling



Dislocations and Subluxations– Result in separation of bony articulating surfaces (diastasis)– Dislocations: Occurs when at least one bone in a joint is

forced out of alignment and must be manually or surgically reduced

• High level of incidence in fingers and shoulder

• Gross deformity is typically apparent with bilateral comparison revealing asymmetry

– Subluxation: Partial dislocations causing incomplete separation of two bones

• Bones come back together in alignment


Dislocations and Subluxations (cont.)• Stabilizing structures of the joint are disrupted

• Joint often becomes susceptible to subsequent dislocations or subluxations

• X-ray is the only absolute diagnostic technique (able to see bone fragments from possible avulsion fractures, disruption of growth plates or connective tissue)

• Dislocations (particularly first time) should always be considered and treated as a fracture until ruled out

• “Once a dislocation, always a dislocation”


Osteoarthritis: Wearing away of hyaline or articular cartilage may expose, erode and polish the underlying bone

• Changes in joint mechanics lead to joint degeneration (the result of repeated trauma to tissue involved)

• May be the result of direct blow, pressure of carrying and lifting heavy loads, or repeated trauma from an activity such as running or cycling

• Commonly affects weight bearing joints but can also impact shoulders and cervical spine

• Symptoms include pain (as the result of friction), stiffness, prominent morning pain, localized tenderness, creaking, grating

• Either generalized joint pain or localized to one side of the joint


Bursitis: Inflammation of the bursae usually at sites of bony prominence between muscles and tendon

• Bursa are synovial fluid filled sacs that develop in areas of friction

• Sudden irritation can cause acute bursitis, while overuse and constant external compression can cause chronic bursitis

• Signs and symptoms include swelling, pain, and some loss of function

• Repeated trauma can lead to calcification and degeneration of internal bursa linings

Questions:

1. What is the difference between an dislocation and a subluxation?

2. What causes osteoarthritis?

3. Where is bursitis commonly found?


Bones



Bone Functions• Body support• Organ protection• Movement (through joints and levers)• Calcium storage• Formation of blood cells (hematopoiesis)

Types of Bone: Classified according to shape• Flat bones - skull, ribs, scapulae• Irregular bones - vertebrae and skull• Short bones- wrist and ankle• Long bones - humerus, ulna, tibia, radius, fibula, femur

- bones most commonly injured


Bone Injuries

• Anatomical Characteristics– Dense connective

tissue consisting of bone cells or osteocytes

– Outer compact tissue

Gross Structures

• Diaphysis -shaft - hollow and cylindrical, covered by compact bone

• Epiphysis - composed of cancellous bone and has hyaline cartilage covering , provides areas for muscle attachment

• Periosteum - dense, white fibrous covering, contains blood vessels and osteoblasts


Bone Growth

Epiphyseal Growth Plate: near the end of each long bone, aid in the growth of bone (growth plate)– Injury to this can cause deformity or disruption in

growth

Bone Diameter caused by

Osteoblasts: bone-producing cells

Osteoclast: bone- remodeling cells

Leads to osteogenesis- bone formation


QUESTIONS:

Name some functions of bones.

Name and describe the 3 gross anatomy of a bone.

How does bone grow?



Bone Fractures:

Closed fractures: where there is little movement or displacement

Open fractures: involves displacement of the fractured ends and breaking through the surrounding tissue– Serious condition if not managed properly

Signs & symptoms• Deformity, pain, point tenderness, swelling, pain on active and passive

movements• Possible crepitus• X-ray will be necessary for definitive diagnosis


Mechanism of Injury• Fracture may be direct (at point of force

application) or indirect • Sudden violent and forceful muscle contraction

Types of FracturesGreenstick: incomplete breaks in the

bone, adolescents

Comminuted: 3 or more fragments at the fracture site

Linear: bone split along its length

Transverse: straight line, more or less a right angle

Oblique: similar to spiral, one end receives torsion while the other is fixed

Spiral: S-shaped separation, foot planted and body twisted in other direction

Impacted: Fall from a height compressing the bone, need traction



Less common types of fractures• Avulsion: Separation of bone fragment from cortex

via pull of ligament or tendon

• Blowout fracture: wall of the eye orbit

• Serrated fracture: saw-tooth fracture line, may cause internal damage

• Depressed fracture: in flat bones, fall or blunt trauma

• Contrecoup fracture: opposite side from the point of trauma


Factors that Affect Bone Strength

• Strength of bone can be impacted by changes in shape and direction

– Long bones with gradual changes are less prone to injury

• Cylindrical and hollow nature of bones make them very strong - resistant to bending and twisting

• Bones can be stressed or loaded to failure by tension, compression, bending, twisting and shearing

QUESTION:

What is the difference between closed and open fracture?

What is a Greenstick fracture?

Where is the bone the “weakest”?



Stress fractures• No specific cause but with a number of possible causes

– Overload due to muscle contraction, altered stress distribution due to muscle fatigue, changes in surface, rhythmic repetitive stress vibrations

• Bone becomes susceptible early in training due to increased muscular forces and initial remodeling and resorption of bone (bones become weaker before stronger)

• Early detection is difficult, bone scan is useful, x-ray is effective after several weeks, MRIs


Typical causes (Mechanism) in sports include:– Coming back to competition too soon after injury

– Changing events without proper conditioning

– Starting initial training too quickly

– Changing training habits (surfaces, shoes….etc)

– Variety of postural and foot conditions

Signs and symptoms – Focal tenderness and pain, (early stages)

– Pain with activity, (later stages) with pain becoming constant and more intense, particularly at night, (exhibit a positive percussion tap test)

– Common sites involve tibia, fibula, metatarsal shaft, calcaneus, femur, pars interarticularis, ribs, and humerus

Question

• What are some athletic mechanisms to stress fractures?



Epiphyseal Conditions • Three types can be sustained by adolescents (injury to

growth plate, articular epiphysis, and apophyseal injuries)– Occur most often in children ages 10-16 years old

• Classified by Salter-Harris into five types (see photo on next slide)

Apophyseal Injuries – Serve as sites of origin and insertion for muscles– Common avulsion conditions include Sever’s disease and

Osgood-Schlatter’s disease


Nerve TraumaReponses Include:

– Hypoesthesia- diminished feeling– Hyperesthesia- increased feeling– Paresthesia- numbness or tingling

Neuropraxia: interruption in conduction of the impulse of the nerve fiber (last hours to months)

Neuritis: chronic inflammation of the nerve (minor to severe- paralysis)

© 2009 McGraw-Hill Higher Education. All rights reserved. Chapter 9: Mechanisms and Characteristics...

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