Return to racing after surgical management of third carpal bone slab fractures in thoroughbred and standardbred racehorses.

Objective: To determine the prognosis for racing of horses surgically treated for slab fractures of the third carpal bone (C3).
Study Design: Retrospective case study.
Animals: Horses (n = 125) surgically treated for C3 slab fractures.
Methods: Medical records of horses surgically treated for dorsal or sagittal C3 fractures were reviewed for age, sex, breed, limb, fracture type, degree of cartilage damage, and surgical treatment. Radiographs were evaluated to determine fracture depth, width, and displacement. Osteophytes, C3 lysis, and fragmentation were scored. Racing performance was obtained from online databases. Univariable and multivariable analyses were used to determine associations between independent variables and outcomes.
Results: Fifty-four (43%) horses raced postoperatively. Among thoroughbreds, 35% (30/86) with dorsal fractures and 63% (17/27) with sagittal fractures raced postoperatively. Among standardbreds, 77% (10/13) with dorsal fractures and 0% (0/2) with sagittal fractures raced postoperatively. Fracture displacement, C3 lysis, and cartilage damage affected the likelihood of racing postoperatively. Placement of 3.5-mm screws vs 4.5-mm screws and the placement of fewer screws were associated with improved likelihood of racing.
Conclusion: The prognosis for postoperative racing of thoroughbreds with dorsal C3 fractures was less favorable than that previously reported. Concurrent joint pathology, such as cartilage damage at time of surgery, affected the ability of the horse to race postoperatively.
Clinical Significance: Although internal fixation of C3 slab fractures is required to restore joint congruity, return to racing should be expected in only 42% of thoroughbreds and 67% of standardbreds.
(© 2019 The American College of Veterinary Surgeons.)