Apical fracture of the proximal sesamoid bone in Standardbred horses: 43 cases (1990-1996)

Objective-To determine whether fracture fragment dimensions, suspensory lig ament damage, and racing status at the time of injury were associated with outcome in Standardbred horses with apical fracture of the proximal sesamoi d bone. Design-Retrospective study. Animals-43 Standardbred racehorses. Procedure-Medical records, racing records, and radiographs were reviewed, a nd ultrasonographic findings were scored. Measurements of the fractured por tion of the proximal sesamoid bone were made. Results-Seventy-four percent (32/43) of horses were pacers, and 26% (11/43) were trotters. Statistical differences between trotters and pacers regardi ng ability to start, number of starts, or amount of money earned after inju ry were not detected. Females earned significantly more money per start aft er injury than males. Eighty-six percent (37/43) of fractures involved hind limbs and 14% (6/43) involved forelimbs. Horses with forelimb injuries ear ned less money per start. Severity of suspensory ligament damage did not af fect postinjury racing performance. A higher proportion of horses that had raced before injury returned to racing after surgery than horses that had n ot raced before injury, although a significant difference between these gro ups was not detected. Eighty-eight percent of horses that raced before inju ry raced after injury. Fifty-six percent of horses that did not race before injury raced after injury. Fracture fragment dimensions did not affect out come. Clinical Implications-Dimensions of the apical fracture fragment of the pro ximal sesamoid bone in Standardbred horses and degree of suspensory ligamen t damage did not affect outcome. Prognosis for return to racing soundness i s good in horses that had raced before injury and fair in horses that had n ot raced before injury.