Orthopaedic disease in young horses

Question 1

How to describe angular limb deformaties

Answer 1

Direction of deviation - valgus or varus
Centre of deviation - fetlock, carpus, tarsus, etc.
Severity - angle of deviation

Question 2

Valgus

Answer 2

Limbs deviate out

Question 3

Varus

Answer 3

Limbs deviate in

Question 4

Aetiology of angular limb deformaties

Answer 4

Congenital
- periarticular laxity
- incomplete ossification of cuboidal bones
- uterine mal-positioning
Acquired
- physitis
- direct trauma

Question 5

How to evaluate a foal with angular limb deformities

Answer 5

Static - stand in front or behind and assess severity of angle
Dynamic - watch foal following the mare
Manipulation - peri-articular laxity
Radiography

Question 6

Conservative treatment of congenital angular limb deformities

Answer 6

Incomplete ossification - box rest, support legs (eg. splints)
Peri-articular laxity - box rest with controlled exercise to build strength

Question 7

Conservative treatment of valgus

Answer 7

Trim lateral hoof wall
Extend medial hoof wall

Question 8

Conservative treatment of varus

Answer 8

Trim medial hoof wall
Extend lateral hoof wall

Question 9

When to do surgical treatment of angular limb deformities

Answer 9

Severe deformity
Conservative treatment has failed
When approaching the age of physeal grown cessation
Persistent ulna

Question 10

How to surgically treat angular limb deformities

Answer 10

Inhibit growth on the long side of the limb
- transphyseal bridge - screws and wire or transphyseal screw
Accelerate growth on short side of the limb
- periosteal strip - periosteum on the short side is transected transversely allowing limb to grow faster (lack of evidence to support efficacy)

Question 11

When to remove implants after surgery for treating angular limb deformities

Answer 11

Regular re-evaluation - approx. every 2wks
Remove when 85-95% straight - straightening continues for a bit after removal

Question 12

What age to growth plates close in the distal radius?

Answer 12

24m

Question 13

What age to growth plates close in the distal metacarpal 3?

Answer 13

6-9m

Question 14

When do the growth plates close in the distal tibia?

Answer 14

17-24m

Question 15

When do the growth plates close in the distal metatarsal 3?

Answer 15

9-12m

Question 16

When should cartilage ossify in utero?

Answer 16

Months 9-11

Question 17

Physitis

Answer 17

Inflammation of the physis at the end of the long bone

Question 18

Triggers of physitis

Answer 18

Rapid growth - high concentrate feed, etc.
Trauma to physis
Genetic predisposition

Question 19

Clinical signs of physitis

Answer 19

Heat
Sweeling
Pain on palpation
Possible lameness
Commonly bilateral

Question 20

Diagnosis of physitis

Answer 20

Radiography
- widening
- sclerosis
- periosteal new bone bridge

Question 21

Treatment of physitis

Answer 21

Exercise restriction
Analgesia - phenylbutazone
Correction of underlying cause - early weaning, reduced feed intake, etc.

Question 22

Describe a type 1 physeal fracture

Answer 22

Straight across the physis
With or without displacement

Question 23

Describe a type 2 physeal fracture

Answer 23

Extends through the metaphysis, producing a chip fracture of the metaphysis

Question 24

Describe a type 3 physeal fracture

Answer 24

Extends through the epiphysis

Question 25

Describe a type 4 physeal fracture

Answer 25

Fracture line extends through the metaphysis, growth plate, and epiphysis

Question 26

Describe a type 5 physeal fracture

Answer 26

Compression/crushed fracture

Question 27

Treatment of physeal fractures

Answer 27

Conservative management - cast, coaptation, and confinement Surgical correction - internal fixation

Question 28

What is the aetiology of soft tissue laxity in foals?

Question 29

What is the aetiology of congenital hyperextension in foals?

Answer 29

Flaccidity of the flexor muscles after birth

Question 30

What is congenital hyperextension in foals?

Answer 30

Sunken palmer/plantar fetlock and elevated toes

Question 31

Treatment of congenital hyperextension in foals

Answer 31

Glue on heel extension shoes to put limb in a normal weight bearing position Normally self-corrects after a few weeks - isolate to small grass pen

Question 32

Treatment of congenital hyperflexion in foals

Answer 32

Light exercise may lead to spontaneous resolve within a few days Toe extension and heel reduction NSAIDs (+ omeprazole) Splints or casts 3 oxytetracycline in 500ml saline, slow IV Rarely require surgery

Question 33

What is the aetiology of acquired hyperflexion in foals?

Answer 33

Rapid bone growth - tendons cannot keep up Specific injury - eg. osteochondrosis, fracture, septic arthritis, foot abscess Pain causes flexion withdrawal reflex and subsequent muscle contraction leading to flexural limb deformity

Question 34

What are the 2 stages of coffin joint contracture?

Answer 34

Stage 1 - dorsal hoof wall has not past vertical (good prognosis) Stage 2 - dorsal hoof wall has progressed past vertical (guarded prognosis)

Question 35

Medical management of acquired coffin joint contracture

Answer 35

Toe extension and heel reduction NSAIDs (+ omeprazole) Reduce growth weight - reduce nutrition, early weaning Address other causes of pain ONLY SUITABLE FOR STAGE 1

Question 36

Surgical management of stage 1 acquired coffin joint contracture

Answer 36

Desmotomy of the accessory (check) ligament of the DDFT In addition to other medical therapies

Question 37

Surgical management of stage 2 acquired coffin joint contracture

Answer 37

Tenotomy of the DDFT In addition to other medical therapies

Question 38

What is the aetiology of acquired coffin joint contracture in foals (1-4m)?

Answer 38

Metacarpal/tarsal bone grow rapidly Leads to functional shortening of the DDFT

Question 39

What is the aetiology of acquired fetlock joint contracture in foals (10-18m)?

Answer 39

Radius/tibia grow rapidly Leads to functional shortening of the SDFT and suspensory ligament

Question 40

What are the 3 stages of acquired fetlock joint contracture?

Answer 40

Stage 1 - fetlock remains behind vertical Stage 2 - fetlock is positioned in front of vertical, but can move behind vertical when weight bearing Stage 3 - fetlock is positioned in front of vertical, even when weight bearing

Question 41

Medical management of acquired fetlock joint contracture

Answer 41

Toe extensions NSAIDs (+ omeprazole) Reduce growth rate - reduce nutrition, early weaning Splint to force fetlock into extension Address other causes of pain ONLY SUITABLE FOR STAGE 1

Question 42

Surgical management of acquired fetlock joint contracture

Answer 42

Depends on the structures involved SDFT - desmotomy of the accessory (check) ligament or SDFT desmotomy DDFT - desmotomy of the accessory (check) ligament or DDFT desmotomy Suspensory ligament - desmotomy In addition to other medical therapies