This article originally appeared in the Fall 2024 issue of EquiManagement. Sign up here for a FREE subscription to EquiManagement’s quarterly digital or print magazine and any special issues.
At the University of Kentucky Equine Veterinary Continuing Education seminar in January 2024, Dwayne Rodgerson, DVM, MS, Dipl. ACVS, of Hagyard Equine Medical Institute, in Lexington, Kentucky, addressed surgical strategies for dealing with angular limb deformities (ALDs). He said ALDs comprise a significant caseload for their practice in the heart of Thoroughbred racehorse breeding country.
Strategic Management of Angular Limb Deformities
Because angular limb deformities have a pronounced effect on future soundness, performance, and athletic longevity as well as a horse’s potential sale, it is important to manage them in a timely and strategic manner. Acquired deviations occur over time, and veterinarians manage certain sites at different times based on growth plate closures:
- Front fetlocks at 60-90 days with closure at four to five months in forelimbs (and eight to nine months in rear limbs)
- The carpus at six to 16 months.
- The tarsus at six to 10 months.
Surgical Management of Angular Limb Deformities
He said the decision to perform surgery depends on many factors: The severity of the deformity, degree of epiphysitis or physitis, history of a mare’s previous foals, conformation of the mare and stallion, along with a farrier’s input of concerns. Because they tend to have finer bone structure, fillies are more at risk of developing ALDs than colts, said Rodgerson.
Historically, a surgical approach sought to accelerate growth on the concave side of the deviation. Surgeons achieved this via periosteal transection and elevation in many cases and by iodine blister or shockwave therapy in other cases. In the presence of physitis, said Rodgerson, these procedures are not likely to improve the outcome, so they are no longer routinely performed.
A New Surgical Approach to Angular Limb Deformities
Instead, the new focus is on deceleration of growth on one side relative to the other using a guided growth procedure called hemiepiphysiodesis. This is performed on the convex side of the ALD using a single percutaneous transphyseal screw. Other methods, such as using screws and wires or plates, transphyseal staples, or growth plate destruction, are associated with a risk of infection, which is counterproductive to managing and resolving the deformity.
Tarsus Surgery
Rodgerson recommends surgery for the tarsus at six to eight months of age, using a self-tapping cortical screw. If performed too early, it is possible to end up with osteochondritis dissecans. Implants are removed when the deviation is corrected. He suggested taking radiographs to determine whether lower hock joints have been crushed.
Hind Fetlock Surgery
Hind fetlock varus is often a congenital deformity, and Rodgerson cautioned against jumping in too quickly. Instead, he recommended corrective trimming first. Don’t intervene until 50-90 days of age, he said. If surgery is indicated, use a 3.5-millimeter cortical bone screw, and remove it as soon as the ALD corrects.
Carpus Surgery
For the carpus, a percutaneous single transphyseal screw is the preferred technique both for positive results and better cosmesis. The 4.5-millimeter self-tapping cortical screw is angled proximal to distal through the distal radius. The procedure can be done in the standing foal at the farm using local anesthetic to block the periosteum. No general anesthesia is required, and both mare and foal stay in their stall for the procedure. This eliminates the stress of transport and surgery at an off-site surgical clinic. Check the limb’s progress after two to three weeks, he advised, then perform follow-ups every one to two weeks to ensure immediate screw removal once the deviation has corrected. Screw removal can also be done on the standing foal at the farm.
Fetlock Surgery
For fetlock correction, Rodgerson proposes the same procedure at the farm as described for the carpus. He says equipment setup takes about five minutes, and he uses a combination of xylazine and ketamine given IV in one injection. All equipment is gas-sterilized, and no instrument tip, incision site, or implant should be touched during the procedure. The hole is drilled, screw placed, radiographs taken to confirm accurate placement, and the small incision closed with Vicryl rapid resorbable suture. A bandage stays intact better with a standing procedure because there isn’t slippage during recovery from general anesthesia. It is important to leave the bandage for two to four days because, as he notes, “inspection leads to infection.”
Related Reading
- Indications for Implant Removal in Horses Following Fracture Repair
- Disease Du Jour: Angular Limb Deformities
- Disease Du Jour: OCD in Horses
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