The treatment of idiopathic osteonecrosis of the medial femoral condyle with arthroscopic debridement.

Five patients with idiopathic osteonecrosis underwent arthroscopic debridement with instruments designed for arthroscopic abrasion arthroplasty. Each lesion was large enough to require total knee or tibial osteotomy using criteria previously published by other authors. Using the Hospital for Special Surgery Rating System, four of five patients were rated good postoperatively (average rating: preop 52 points and postop 82 points). Biopsies of two patients at repeat arthroscopy showed that fibrocartilage fills in the defects created by the debridement. Average follow-up was 31 months.