Flexural deformities

Question 1

Which anatomical plane do they occur in?

Answer 1

• the sagittal plane
  – therefore assessed by viewing from the side

Question 2

Are they more common in the fore or hindlimbs?

Answer 2

• Forelimbs

Question 3

More commonly unilateral or bilateral?

Answer 3

• bilateral

Question 4

Laxity vs Contracture

Answer 4

• laxity = hyperextension
  – joint sinking towards the ground
• contracture = hyeprflexion
  – joint flexed

Question 5

Is congenital hyperextension common?

Answer 5

• yes

Question 6

Which part of the limb is usually affected by congenital hyperextension?

Answer 6

• the distal limb: fetlock and phalangeal joints

Question 7

Clinical signs of congenital hyperextension

Answer 7

• elevated toe
• palmar/plantar fetlock is sunken

Question 8

Cause of congenital hyperextension

Answer 8

• flaccidity of flexor muscles after birth

Question 9

Tx of congenital hyperextension

Answer 9

• usually self corrects within a few weeks
  – confine to a small grass pen
  – want a firm surface for them to stand on, whilst getting exercise so a small grass pen is good
• skin abrasions may occur on palmar/plantar fetlock
  – protect with bandages
• glue on heel extension shoes may be required (if doesn’t resolve on its own)

Question 10

What can congenital hyperflexion cause?

Answer 10

• dystocia
• inability of the foal to stand (due to inability to get its leg straight)

Question 11

Where does congenital hyperflexion occur?

Answer 11

• coffin joint
• pastern joint (rarely)
• fetlock
• carpal joints
• tarsal joints

Question 12

Congenital hyperflexion – medical treatment

Answer 12

§ Light exercise – spontaneously resolve in a few days.
– If a mild problem and the foal is able to weight bear and walk around

§ 3g oxytetracycline in 500ml saline slow IV.
→ within a few days of birth (usually within 48h, definitely within 1wk of birth)
→ inhibits tractional structuring of collagen fibrils.
→ tendons & ligaments more susceptible to elongation during normal weight bearing.

§ Toe extensions and heel reduction.
→ stretches musculotendinous unit during weight bearing.

§ NSAIDs (and omeprazole)
– As stretching of the tendons is painful

§ Splints or casts.
→ encourages relaxation of the musculotendinous unit.

Question 13

Why when giving NSAIDs to a foal must you also give omeprazole?

Answer 13

• Bigger risk of GI ulceration, so must give omeprazole as a gastro-protectant

Question 14

Congenital hyperflexion – surgical treatment

Answer 14

• if medical tx fail – rarely required

Question 15

Acquired hyperflexion - cause

Answer 15

§ Pain cause flexion withdrawal reflex and subsequent muscle contraction.

Pain due to:
1) Rapid bone growth with tendons unable to keep up
→ functional shortening of tendons
→ resulting tension in tendon is painful
2) Specific injury e.g. osteochondrosis, fracture, septic arthritis, foot abscess

Question 16

Another term for acquired coffin joint contracture

Answer 16

• Club foot

Question 17

Acquired coffin joint contracture - age affected and why

Answer 17

§ 1-4 months old
→ Metacarpal / tarsal bones growing rapidly
→ Functional shortening of DDFT (as it can’t grow at the same speed as the metacarpal/tarsal bones)

Question 18

Acquired coffin joint contracture - stages

Answer 18

§ Stage 1: dorsal hoof wall has not past vertical – good prognosis

§ Stage 2: dorsal hoof wall has progressed past vertical – guarded prognosis

Question 19

Acquired coffin joint contracture – medical management

Answer 19

§ Toe extensions and heel reduction.
→ stretches DDFT musculotendinous unit during weight
bearing.

§ NSAIDs (and omeprazole).

§ Reduce foals growth rate by reducing nutrition → reduce feed to foal and mare
– reduce mares milk by reducing her nutrition
– reduce creep feeding to the foal itself
→ early weaning

§ Address other causes of pain
– e.g. osteochondrosis or fracture

§ Suitable for stage 1 only

Question 20

Acquired coffin joint contracture stage 1 – surgical management

Answer 20

• Desmotomy of the accessory (check) ligament of the DDFT
  → proximal cannon under short G.A.
  → good prognosis as an athlete
  – sectioning the check ligament reduces some of the tension and pull of the DDFT on the pedal bone

Performed in addition to medical therapies

Question 21

Acquired coffin joint contracture stage 2 – surgical management

Answer 21

• Tenotomy of DDFT
  → mid cannon or palmar pastern
  → guarded prognosis as an athlete
  – partly because it is harder to correct the deformity and also because sectioning of the DDFT creates problems on its own

Performed in addition to medical therapies

Question 22

Acquired fetlock joint contracture - age affected and why

Answer 22

§ 10-18 months old
→ Radius / tibia growing rapidly
→ Functional shortening of SDFT and suspensory ligament.
– As their growth can’t keep up with that of the bones

Question 23

Acquired fetlock joint contracture - stages

Answer 23

§ Stage 1: Fetlock remains behind vertical

§ Stage 2: Fetlock positioned in front of vertical, but can move behind vertical during weight bearing.

§ Stage 3: Fetlock positioned in front of vertical always.

Question 24

Acquired fetlock joint contracture – medical management

Answer 24

§ Toe extensions
– to increase the stretch of the tendons

§ NSAIDs (and omeprazole)
– for the pain

§ Reduce foals growth rate by reducing nutrition → reduce feed to foal and mare
→ early weaning
§ Splint (or bandage) to force fetlock into extension

§ Address other causes of pain

§ Suitable for stages 1 only.

Question 25

Acquired fetlock joint contracture – surgical management

Answer 25

§ Careful palpation under G.A. with limb in full extension reveals which structure(s) is causing contracture.
§ Procedure performed depends on structure(s) involved and severity
§ Performed in addition to medical therapies

Question 26

Acquired fetlock joint contracture – surgical management if SDFT causing contracture

Answer 26

Mild → Desmotomy of the accessory (check) ligament of the SDFT

Stages 2 or 3 → SDFT Desmotomy (guarded for athletic use)

Question 27

Acquired fetlock joint contracture – surgical management if DDFT causing contracture

Answer 27

Mild → Desmotomy of the accessory (check) ligament of the DDFT

Stages 2 or 3 → DDFT Desmotomy (guarded for athletic use)

Question 28

Acquired fetlock joint contracture – surgical management if suspensory ligament causing contracture

Answer 28

→ Suspensory ligament Desmotomy (guarded for athletic use)