Equine Distal Limb Ultrasound

Question 1

What is the SDFT? Where does it insert?

Answer 1

The superficial digital flexor tendon works with the superficial digital flexor muscle to make the lower leg move. The SDFT emerges from its parent muscle, the superficial digital flexor muscle, which is located above the carpus (knee) or hock. It is the most prone to injury due to being the most superficial.

Extends the digit, assists in extending the hock and flexing the stifle as part of the reciprocal apparatus (forces the hock and stifle to flex and extend in unison).

Function: Flex and stabilise the fetlock

Insert: Middle phalanx (P2)

Question 2

What is the DDFT? Where does it insert?

Answer 2

The DDFT runs on the plantar aspect of the metatarsus distally, over the distal sesamoid (navicular bone). Its passage over the navicular bone is facilitated by the synovial fluid-filled navicular bursa.

Function: Flexes the distal phalanx

Insert: Distal phalanx (P3)

Question 3

What is the check ligament? Where does it insert?

Answer 3

The accessory (check) ligament connects the DDFT to the third metatarsal (cannon) bone. This forms part of the stay apparatus by removing tension from the main body of the DDFT.

Stay apparatus - arrangement of muscles, tendons and ligaments that work together so that an animal can remain standing with virtually no muscular effort.

Question 4

What is the suspensory ligament? Where does it insert?

Answer 4

Function: Prevents fetlock hyperextension and limits plantar flexion

Insert: Proximal Sesamoid Bones

Question 5

How many ultrasound zones are there in a distal limb ultrasound?

Answer 5

3 zones

Question 6

What can you see in zones 1 and 2?

Answer 6

SDFT, DDFT, check (accessory) ligament, suspensory ligament

Question 7

What can’t you see in zone 3

Answer 7

Check (accessory ligament) because it has become ‘one’ with the DDFT.