Arthroscopic findings in the carpal joints of lame horses without radiographically visible abnormalities: 41 cases (1986-1991).

Arthroscopy was performed in 1 carpal joint unilaterally in 27 horses and either in 2 carpal joints unilaterally or 1 carpal joint bilaterally in 7 horses. All horses were lame, but the cause of lameness could not be determined from radiographs. Twenty-seven carpi did not have radiographically visible abnormalities; the remaining 14 had only mild to moderate lucency or sclerosis of the radial facet of the third carpal bone. The primary abnormalities identified during arthroscopy included a crush fracture of the third carpal bone (7 carpi), an incomplete fracture of the third carpal bone in the frontal plane (13 carpi), an incomplete fracture of the third carpal bone in the sagittal plane (1 carpus), a crush fracture of the radial carpal bone (1 carpus), a chip fracture of the intermediate carpal bone (1 carpus), damage to the articular cartilage of the third carpal bone (12 carpi), tearing or fraying of the medial palmar intercarpal ligament (4 carpi), and synovitis (2 carpi). All of the horses in this study were racehorses (29 Standardbreds and 5 Thoroughbreds), and race records were used to evaluate performance before and after surgery. Twenty-four of 34 horses raced preoperatively, and 25 of 34 raced postoperatively. Twenty-three of the 27 (85%) horses in which a single joint was examined raced postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)