Imaging the Equine Foot

Question 1

How high are incidences of lameness in the foot?

Answer 1

80% of lameness in horses occurs in foot

Question 2

Describe the anatomy of the foot:

Answer 2

lot of soft and bony tissue in the foot, encapsulated by rigid hoof capsule - making it difficult to swell
(also difficult to palpate and carry out ddx)

Question 3

How can you examine the foot without imaging?

Answer 3

Inspection of hoof wall/sole
Palpation at coronary band - join of coffin bone extends beyond CB - feel effusion
Hoof testers + percussion
Diagnostic analgesia - Nerve blocks (lot of structures though)

Question 4

How do you prepare the foot for rads?

Answer 4

Brushing away dirt, remove loose horn and stones from frog sulci
Placement of marker on dorsal hoof wall, aligned with coronet
Shoe removal if covering region of interest
Packing with play-doh

Question 5

What are the routine views for radiographs of the foot?

Answer 5

Lateromedial
Dorso-60°-proximal palmarodistal oblique (upright pedal)
Dorso-45°-proximal palmarodistal oblique (upright pedal)
Palmaro-45°-proximal palmarodistal oblique (flexor view)

Question 6

What makes analysing rads difficult?

Answer 6

Variations of normal anatomy
-Could be secondary centres of ossifications sites - not chip fractures - variation of ossification

• compare to the other foot to see if pathological
• palpate on the outside - if points to any issues

-attachments of collateral ligaments of DIP joint

Question 7

What can you see better in the dorso-60°-proximal palmarodistal oblique (upright pedal)?

Answer 7

Collimated for navicular bone, distal phalanx

Question 8

What variations in normal radiographic anatomy in the 60°-proximal palmarodistal oblique (upright pedal) view?

Answer 8

Crena - middle of the dorsal solar margin
Attachement of collateral ligaments of the DIP joint
Lot of variations for the navicular bone!

Question 9

What pressures are on the navicular bone?

Answer 9

DDFT runs on the flexor side and puts pressures on the nb - hyaline cartilage cannot cope

Question 10

What do you measure in a radiograph of the dorsopalmar foot?

Answer 10

Radiographic appraisal:

measuring foot balance - if the foot is too flat, correct toe length

Question 11

What radiographic signs are seen in horses with laminitis?

Answer 11

Lucent line in dorsal hoof wall - separation of lamina
Horizontal lucent lines at coronet: sinking
Remodelling (slipper) and fracture of solar margin - chronic

Question 12

What measurements are used to look for laminitis?

Answer 12

Laminitis measurements: angle of the dorsal wall and dorsal wall distal phalanx >15° poor prognosis

Founder distance >13mm indication of sinking

Dorsal wall thickness >3cm in horses, 2cm in ponies = indicator for chronic laminitis

Question 13

What can you see on a radiograph for navicular disease?

Answer 13

‘Spurs’
Proximal border build up
Attachment of collateral ligaments
loss of corticomedullary junction
lucency in NB - less bone - painful on distal edge
pathognomonic radiological sign - flexor cortex erosions
Abnormal distal border synovial fossae

Question 14

What is keratoma?

Answer 14

Abnormal horny tissue present at white line - loss of bone at distal phalanx

splitting and deviation of white line around abnormal horn - well defined margins

Question 15

What does Pedal bone osteitis look like on rads?

Answer 15

Moth eaten infection - abscess

Question 16

What is a sequestrum?

Answer 16

Dead bone - see lucency around it

Question 17

What other technique is used to diagnose navicular syndrome?

Answer 17

MRI
See: 
Navicular bone
DDFT
Navicular bursa
DIP joint
Collateral ligament DIP joint
Collateral ligament of NB
Impar ligament