Computed tomographic assessment of fracture characteristics and subchondral bone injury in Thoroughbred racehorses with lateral condylar fractures and their relationship to outcome.

Abstract

To investigate the effects of fracture characteristics and concurrent subchondral bone pathology identified with computed tomography (CT) on the racing performance of Thoroughbred racehorses with fractures of the MC3/MT3 lateral condyle. Retrospective cohort study. Thoroughbred racehorses (n=50) with a fracture of the MC3/MT3 lateral condyle, which had preoperative CT and internal fixation performed. Medical records were reviewed for age, sex, limb, and surgical treatment. Computed tomography scans were evaluated to determine fracture characteristics including length, whether the fracture was incomplete or complete, and displacement. The presence of subchondral bone injury (SBI), sesamoid bone fracture, articular comminution, and fragmentation in the joint was noted. Racing data was obtained from an online database. Univariable and multivariable analyses determined associations between independent variables and outcomes. Thirty-three (66%) horses raced after surgery. Horses with sesamoid bone fractures (P=.021), MC3/MT3 comminution (P=.016) and intra-articular fragmentation (P=.015) were less likely to race postoperatively. Concurrent SBI did not affect outcome. In the final multivariable model, sex (P=.015) and whether a fracture was incomplete or complete (P=.007) were the most significant predictors of racing postoperatively with females and horses with complete fractures being less likely to race. The prognosis for racing after a lateral condylar fracture is favorable but is decreased in horses with complete fractures and certain concurrent joint pathology. Horses presenting with lateral condylar fractures commonly have concurrent joint pathology. Computed tomography can aid in preoperative evaluation and prognostication by enabling more complete fracture assessment.