27.6.1: Angular limb deformities

Question 1

Types of angular limb deformities

Answer 1

• Varus
• Valgus

L - valgus = foot goes laterally as pictured

Question 2

Causes of angular limb deformities

Answer 2

Incomplete ossification
* Premature foal
* Dysmature foal
* Placentitis during gestation
* Mare colic during gestation or heavy parasite burden (lack of uterine blood supply)
* Abnormal uterine positioning

Peri-articular laxity
* If uncomfortable on one limb, puts lots of weight on the other leg

Angular limb deformities can be congenital or acquired.

Question 3

How to evaluate angular limb deformities

Answer 3

• Static exam: stand perpendicular to the frontal plane
• Dynamic exam
• Manipulation: check for peri-articular laxity
• Radiography: compare both legs, minimum 2 orthogonal views; essential if premature or dysmature foal
• Find origin of deviation e.g. persistent ulna common in mini horses but not so much full-sized ones; this can contribute to the angular limb deformity

Question 4

Answer 4

Tarsus varus

Question 5

Answer 5

Tarsus valgus

Question 6

Conservative treatment of angular limb deformities

Answer 6

• Box rest and controlled exercise (stable + small bit of handwalking) if normal ossification and peri-articular laxity
• Box rest only if incomplete ossification
• Trimming/ rasping the foot e.g. for carpus and fetlock varus
• Glue on shoes / extension e.g. for carpal valgus and fetlock varus

Question 7

How would you treat carpus valgus with trimming and rasping?

Answer 7

Carpus valgus
* Trim the lateral hoof wall (this side would be longer)
* We tolerate a bit (2-5 degree) in neonatal foals as we know it corrects eventually

Question 8

How would you treat fetlock varus with trimming and rasping?

Answer 8

Fetlock varus
* Trim medial hoof wall

Question 9

How would you treat carpal valgus with extensions?

Answer 9

Carpal valgus -> extension medial

Question 10

How would you treat fetlock varus with extensions?

Answer 10

Fetlock varus -> extension lateral

Question 11

Surgical treatment of angular limb deformities

Answer 11

• Growth retardation (shutting down growth on one side of the physis, allowing the other to catch up)
• This needs to be done when the growth plate is open and when rapid growth is occurring
• Monitor the foal and remove the screw before it corrects the other way
• It will continue to correct a short while after implant removed

Pictured: transphyseal bridge, transphyseal screw

Question 12

How do you know when to remove an implant used to correct an angular limb deformity?

Answer 12