Catastrophic Complication After Removal of Distal MT4

A 12yo French Standardbred gelding is admitted on emergency because he was found on pasture with a non weight bearing lameness RH and a wound on the lateral aspect of MT3, approximately between the proximal and middle third of the length of MT3. After clinical and radiographic examination, an open, infected, comminuted fracture of MT4 is diagnosed. The horse is initially treated with regional iv perfusions, systemic antibiotics and NSAIDS, and wet-to-dry bandages. The lameness quickly improves and the horse puts full weight on the limb after 24h. Two days later, the fracture and the wound are debrided with the horse standing.

Six weeks after admission, the wound is closing, there is minor drainage and the horse is sound at the walk. Control radiographs show progressive healing of the fracture site but a large defect and some fragments remain.

Ten weeks after initial admission, the wound is healed. The fracture site shows a large defect and small fragments remain. The horse is kept on box rest and hand walking.

Twelve weeks after the initial admission, the horse is hospitalized for removal of the distal aspect of MT4. Surgery is performed under general anesthesia, on left lateral recumbency. A standard approach is used. The fracture bed is curetted, some necrotic bone and fibrotic soft tissue are removed from the fracture site. MT4 is amputated just proximal to the fracture using an oscillating saw. During the procedure, a chisel is placed between MT3 and MT4 to prevent sawing of the cannon bone. Surgery is uneventful. A Robert Jones bandage is applied on the distal limb. The horse is recovered without ropes. After one attempt to stand, the horse falls on its right side. At this time, a catastrophic open fracture of MT3 occurs, at the level of MT4 ostectomy. The horse is euthanized in the recovery box.