A lag-screw technique for bridging of the medial aspect of the distal tibial physis in horses.

This research examines a surgical technique, known as a lag-screw technique, used for the correction of tarsal valgus deformities in young horses. The researchers utilized the technique on 11 foals and reported positive results, with the deformity resolved in all cases.

Procedure of the Lag-Screw Technique

• The procedure begins with the foal (a young horse) wbeing put under anaesthesia.
• A stab incision is made in the skin down to the underlying bone in the most distal part of the medial malleolus, the bony prominence found on the inner side of the ankle.
• A 20-gauge needle is then inserted into the incision to guide the placement of the lag screw. This screw is inserted in a direction parallel to the medial cortex, the outer part of the tibia (shin bone), and guided by radiography.
• The screw is not removed until the tarsal valgus deformity, an abnormal outward angulation of the tarsal joint (or hock) of horses, has evidenced a clinical improvement of at least 80%.

Research Subjects and Findings

• The subjects of this study were 11 foals, 6 of which had bilateral tarsal valgus deformities and 5 had unilateral tarsal valgus deformities. All these horses displayed a tarsal valgus deformity of more than 7 degrees prior to the surgery.
• The mean age at the time of surgery was 220 days, with an age range from 116 to 364 days.
• The lag screws remained in place for an average of 62 days; the shortest time being 39 days and the longest 89 days.
• The study reported that the tarsal valgus deformity was resolved in all 11 horses. Along with the functional improvement, excellent cosmetic results were achieved.