Osteochondritis dissecans.

Osteochondritis dissecans is a rare orthopaedic disorder of unknown etiology. Advances in CT and MRI scanning have increased our knowledge of the disorder, but arthroscopy remains the principle means of monitoring its progress. Arthroscopic surgery has displaced traditional arthrotomy in many instances and is useful in retrieval of loose bodies, drilling of osteochondral fragments, retrograde bone grafting, and abrasion arthroplasty. Arthrotomy continues to be the best method of pinning and bone grafting of detached lesions. Advances in transplant surgery now permit large craters to be patched with osteochondral allografts.