Arthroscopic removal of abaxial fracture fragments of the proximal sesamoid bones in horses: 47 cases (1989-1997).

Objective: To determine the outcome of horses after arthroscopic removal of abaxial fracture fragments of the proximal sesamoid bone and association of fracture grade with outcome.
Design: Retrospective study.
Animals: 47 horses.
Procedure: Information obtained from dorsopalmar and dorsoplantar radiographic views of metacarpophalangeal and metatarsophalangeal joints was used to classify fractures as grade 1 (< 15 mm long), grade 2 (15 to 25 mm long), and grade 3 (> 25 mm long) and type 1 (abaxial) and type 2 (apical-abaxial). Outcome was determined by whether the horse returned to its intended use, raced in the same class or higher (racehorses), or performed satisfactorily (nonracehorses). Number of starts, performance index, and money earned were also used to evaluate performance of racehorses.
Results: Follow-up information was obtained for 41 horses (35 racehorses, 6 nonracehorses). Twenty-five racehorses were able to return to racing (16 in the same class, 9 in a lower class). All 6 nonracehorses were able to return to performance at the same level. Horses with small fracture fragments or fractures involving the abaxial aspect of the proximal sesamoid bone only had a more favorable outcome, compared with horses with large or apical-abaxial fractures.
Clinical Implications: Overall, horses with abaxial fractures of the proximal sesamoid bone have a favorable prognosis for return to racing, but only a fair prognosis for return to racing in the same class, after arthroscopic removal of fracture fragments. Successful results can be expected for nonracehorses.