Factors associated with racing performance of Thoroughbreds undergoing lag screw repair of condylar fractures of the third metacarpal or metatarsal bone.

Abstract

To evaluate effects of sex, fracture configuration, affected limb, and screw placement on outcome of Thoroughbreds with condylar fractures involving the third metacarpal or metatarsal bone. Cohort study. Animals-56 horses. Age, sex, affected limb, fracture configuration, fracture length, fracture fragment width, and distance of the most distal screw from the articular surface were analyzed in logistic regression models. Females were more likely to have displaced fractures and race in fewer races after surgery than males. Sex and fracture configuration were associated with number of postoperative races. Among horses that returned to racing, those with thicker fracture fragments were 11 times as likely as horses with thinner fracture fragments to win a race after surgery. Horses with longer fractures and older horses had fewer postoperative races. Horses in which the most distal screw had been placed further from the joint surface had more races. Results suggest that female horses with displaced condylar fractures and male horses with nondisplaced condylar fractures are more likely to be referred for treatment. The effect of sex on outcome for these horses cannot be clearly separated from the effect of fracture configuration. When adjusted for fracture configuration, males were 6 times as likely as females to race after surgery. When adjusted for sex, horses with nondisplaced fractures were 17 times as likely as horses with displaced fractures to race after surgery. Results suggest that the most distal screw should be placed above the epicondylar fossa.