Transection of the accessory ligament of the superficial digital flexor muscle for the treatment of superficial digital flexor tendinitis in standardbreds: 40 cases (1988-1992).

Medical records of 40 racing Standardbreds with superficial digital flexor tendinitis that underwent transection of the accessory ligament of the superficial digital flexor (SDF) muscle (superior check desmotomy) were reviewed. Surgery was performed bilaterally in 32 horses and unilaterally in 8. Concurrent palmar annular desmotomy was performed in 8 horses in which tendinitis involved the distal metacarpal region and confinement of the deep and SDF tendons by the annular ligament was suspected. Follow-up information was obtained for 32 horses, by telephone, and racing results were available for 39 horses (1 horse is currently in training, but had a qualifying race prior to surgery). Tendinitis recurred in 8 of 32 (25%) horses that returned to training. Thirty-five of 38 (92%) horses started at least 1 race after surgery. Mean +/- SD time between surgery and first race was 237 +/- 86 days. Overall, 33 of 38 horses completed 5 or more races after surgery; however, SDF tendinitis recurred in 6, and treatment was, therefore, considered to be successful in 27 horses. Horses started a median of 18 races after surgery. Median amount of money won per start after surgery (median, $418; range, $0 to $4,626) was significantly less than median amount won per start before surgery (median, $1,155; range, $0 to $14,603). Inflammation of the interosseous muscle (suspensory ligament) developed in 5 horses with bilateral SDF tendinitis and in 2 horses with unilateral SDF tendinitis. All horses with inflammation of the interosseous muscle had undergone bilateral superior check desmotomy.