OSTEOCHONDRAL FRAGMENTATION OF THE PLANTAR PALMAR PROXIMAL ASPECT OF THE PROXIMAL PHALANX IN RACING HORSES

The clinical presentation and outcome of treatment is presented for 26 cases of osteochondral fragmentation of the plantar/palmar proximal a spect of the proximal phalanx. Twenty-three were racing Standardbreds and three were racing Thoroughbreds. The most common reason for presen tation was an inability to run straight at high speed. Only eight hors es presented for lameness, although on examination 19 were lame. A pos itive flexion test was recorded in 90% of affected fetlock joints and effusion in 48%. Arthroscopic fragment removal was performed on 23 occ asions in 21 horses and arthrotomy in one horse. Of the 16 horses that had returned to racing, 12 had improved their performance, while thre e showed no improvement, and one was retired for other reasons. In thr ee horses refragmentation occurred after surgery, two of which had imp roved after initial arthroscopic removal. Degenerative changes within the fetlock joint were detected at surgery in eight horses. Of the fou r horses treated conservatively, one returned to its previous level of performance temporarily after intra-articular medication, one showed no improvement and two were still resting. Plantar/palmar osteochondra l fragmentation of the proximal aspect of the first phalanx is a commo n cause of low-grade lameness in racing horses, and arthroscopic remov al results in improvement in race performance in a high percentage of cases.