Angular limb deformities in foals

Question 1

What is an angular limb deformity? How is it described?

Answer 1

Deviation from the long axis of the limb in the frontal plane
- observed when foal viewed from in front or behind

Described according to:
1) Direction of deviation – valgus or varus
2) Centre of deviation – fetlock / carpus / tarsus etc
3) Severity – angle of deviation

Question 2

What type of angular limb deformity is this?

Answer 2

Valgus - L for lateral

Question 3

What type of angular limb deformity is this?

Answer 3

Varus

Question 4

Why do we get angular limb deformities?

Answer 4

Congenital – present from birth
* periarticular laxity
* incomplete ossification of cuboidal bones
* uterine malpositioning

Acquired – asymmetrical growth across physis
* physitis
* direct trauma

Question 5

What are the steps to angular limb deformity investigations?

Answer 5

Static
- Stand in front / behind
- assess severity

Dynamic
- Following the mare

Manipulation
- Peri-articular laxity

Radiography
* Origin of the deviation
* Severity – measure angle
* Incomplete ossification

Question 6

What is the conservative treatment options for congenital angular limb deformities?

Answer 6

• Incomplete ossification – box rest
• Peri-articular laxity (but normal ossification) – box rest with controlled exercise

Question 7

What is the conservative treatment options for acquired angular limb deformities?

Answer 7

Valgus
- Trim lateral hoof wall
- Extend medial hoof wall

Varus
- Trim medial hoof wall
- Extend lateral hoof wall

Question 8

Why would you pick surgical treatment for angular limb deformities? What is the procedure? When do you take the implants out?

Answer 8

When to use
- Severe deformity
- Conservative treatment failed
- When approaching age of physeal growth cessation
- distal metacarpus/tarsus - 4 months
- distal radius / tibia - 18 months
- Persistent ulna
- Usually in miniature horses

What to do
* Inhibit growth on long side of limb
* Transphyseal bridge
* screws & wire
* transphyseal screw (screw that growth thorugh GH into epiphyses)

Implant removal
* Regular re-evaluation required
* approx. every 2 weeks
* Remove implant when almost straight (85-95% straight)
* straightening will continue a bit once implants removed