Osteochondral fractures (chip fractures) of the carpal bones are a common cause of lameness in racehorses. The primary etiological factor is trauma, usually associated with fast exercise. Chips typically occur on the dorsal aspect of the joint.
In the middle carpal joint, the most frequent sites of chip fracture are the distal radial carpal bone, proximal third carpal bone, and distal intermediate carpal bone. In the radiocarpal joint, the most common locations are the proximal intermediate carpal bone, distal lateral radius, proximal radial carpal bone, and distal medial radius.
Diagnosis of carpal bone fractures is based on radiographic demonstration of osteochondral chip fragment(s). Arthroscopic fragment removal is the treatment of choice. The overall prognosis is highly dependent on the degree of articular cartilage damage as identified on arthroscopy.
Carpal Slab Fractures in Horses
Slab fractures extend from one articular surface to another articular surface. In the carpus, slab fractures occur in both frontal and sagittal planes. The most common fracture is frontal slab fracture of the radial facet of the third carpal bone (see image).
The treatment of choice for carpal slab fractures is lag screw fixation with arthroscopic guidance for fractures > 10 mm, or removal of the fracture fragments if they are thin or not amenable to lag screw fixation.
Courtesy of Dr. Matthew T. Brokken.
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Also see pet owner content regarding fracture of the carpal bones in horses.
