Equine Radiographic Anatomy

Views of the hoof Lateromedial Dorsopalmar

Lateral radiograph of the equine foot

P1

P2

P3

Anatomy: • First phalanx • Second phalanx • Third phalanx • Navicular bone • Proximal interphalangeal joint •Distal interphalangeal joint Navicular bone

Proximal interphalangeal joint AKA pastern joint

Distal interphalangeal joint AKA coffin joint

Distal limb anatomy

• Extensor process of P3

• Common digital extensor

• Deep digital Flexor

• Straight sesmoidean ligament

• Insertion of oblique sesmoidean ligament

• Impar ligament

• Digital cushion

Articular surface Proximal

surface

Flexor surface

Distal surface

Lateral radiograph of the equine foot

5

Views of the hoof • Dorsal proximal to palmar distal

( Upright pedal )

• Good view to asses solar margin of P3 and the navicular bone

Dorsal proximal to palmar distal

•Navicular bone •Coffin bone/P3 •Vascular channels • Solar margin • Semilunar canal • Wings of the coffin bone

Dirt in the white line on bottom of hoof

Vascular channels

Crena margins solearis

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Crena margins solearis - a smooth rounded concavity of the distal phalanx solar margin (more prominent in hindlimb)

Views of the hoof

• Palmar proximal to palmar distal ( Skyline )

• Good view to asses flexor surface and medullary cavity of the navicular bone

Palmar proximal to palmar distal (skyline)

•Navicular bone •Flexor surface •Medullary cavity • Wings of coffin bone

Dorsoproximolateral to palmarodistomedial-

To throw out the lateral wing of P3.

Equine Metacarpal-phalangeal joint Fetlock

Lateral Dorsal palmar DLPMO

• Proximal sesamoids • Lateral condyle of MC3

• Ergot • Sagittal ridge

MC3

P1

MC4 Prox. Sesamoids

Flexed lateral

The only way to know medial versus lateral and which limb is radiographed is if the film was correctly labeled at the time the image was obtained.

The views

• Radiographs are named by the direction through which the photons transverse the patient.

Lateral Medial

Dorsal

Palmar

• Dorsopalmar radiograph of the carpus

Dorsopalmar view equine carpus

Lat. Styloid process

Radius

Radial CB

Inter-mediate CB Ulnar CB

Third CB 4th CB

2nd CB

MC3 MC4

Dorsal view of the carpal bones

MC2

R I U

A

2 3 4

MC2 MC3 MC4

The views

Lateral Medial

Dorsal

Palmar

• Lateromedial

• Radiographs are the most sensitive on the edges

Flexed views

• Manipulation of the limb to better image anatomic structures of interest.

• Visualization of articular surfaces

Lateral views of the equine carpus

Flexed lateral radiograph of the carpus

Anatomy: • Radial carpal bone • Intermediate carpal bone • Ulnar carpal bone • C3 • C4

* Need to know how to differentiate between radial and intermediate carpal bones and C3 versus C4. So if there is a chip fracture, you can tell the surgeon which bone is fractured.

Three main joints: • Radial carpal •Middle carpal •Carpal metacarpal

Dorsolateral to palmaromedial

Lateral

Dorsal

Medial

Palmar

• Palmar-lateral structures such as the lateral splint bone are easily seen in this view.

Dorsolateral to palmaromedial radiograph of the equine carpus

Palmar lateral su

rface D

ors

al m

edia

l su

rfac

e

C4

MC4

Accessory carpal bone curled around and well projected. Articulates with ulnar carpal bone.

R

C3

On the lateral surface, the fourth carpal bone is not aligned with MC4

Dorsomedial to palmarolateral

L Medial

Dorsal

Palmar

• There is summation of structures in the middle,

such as the lateral splint bone.

Dorsomedial to palmarolateral radiograph of the equine carpus

Do

rsal

late

ral s

urf

ace

Palm

ar med

ial surface

C2

MC2

Medially the second carpal bone stacks up nicely on top of MC2.

Accessory carpal bone is poorly visualized.

DMPLO Equine Carpus

C1

• The first carpal bone is sometimes present and the fifth carpal bone is rarely present. They are non-articular, will vary in size, have smooth margins and may be present on one side only.

C2

MC2

Sky line views

Lateral to medial radiograph of the equine tarsus

Anatomy:

1. Tibia

2. Calcaneous

3. Chestnut

4. Tarsocrural joint

5. Proximal intertarsal joint

6. Distal intertarsal joint

7. Tarsometatarsal joint

8. Metatarsal 3

1

3

2

4

5

6

7

8

Dorsoplantar view of the equine tarsus

TIBIA

MT3

TB3 Central TB

Medial malleolus

Lateral malleolus

TB 4

Lateral trochlear ridge of the talus

Medial trochlear

ridge of the talus

DIRT

MT3

DIRT Medial malleolus

Lateral malleolus

Medial

trochlear

ridge of

the talus

Dorsal view of the tarsus

TB 4

TB3

4 2

Central TB

DLPMO

• Calcaneous

• Distal intermediate ridge of the tibia

• MT4 – Lateral splint bone

• MT2 – Medial splint bone

• Fourth tarsal bone

• Medial mallelous

• Lateral trochlear ridge of the talus

• Sustentaculum tali

• T1 and T2 fused

• Dorsolateral surface of the tarsometatarsal joint

Dorsomedial to palmar lateral radiograph of the tarsus

Hook Medial trochlear ridge of the femur

Lateral trochlear ridge of the femur

Patella

Femoral condyles

Tibial condyles

Tibial tuberosity

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Lateromedial view equine stifle

The medial trochlear ridge is larger than the lateral trochlear ridge.

Extensor fossa of femur

Extensor groove of tibia

Caudal to cranial radiograph of the equine stifle

Anatomy:

• Medial condyle

• Lateral condyle

• Medial intercondylar eminence

• Fibula

• Medial tibial condyle

The fibula can have multiple separate centers of ossification. Do not mistake these as fractures.

“In the barn terminology”

• Knee carpus

• Cannon bone MC3

• Splint bones MC2 and MC4 in horses

• Fetlock metacarpal phalangeal joint

• Pastern joint Proximal interphalangeal joint

• Coffin joint Distal interphalangeal joint

• Coffin bone Distal phalanx