Osteoarticular allografts to treat distal femoral osteonecrosis.

Allografts, which are among the limited number of treatment options for young patients with large defects of the distal femur, offer a physiologic method of restoring knee function. Since 1980, 21 patients younger than 50 years old who had osteonecrosis involving large portions of the distal femur were treated with fresh-frozen osteoarticular surface replacements. This retrospective review evaluated the 15 patients (17 knees) whose follow-up time was greater than two years. The patients were reevaluated at regular intervals by one or more of the authors. Follow-up time ranged from two to nine years (mean, 4.2 years). Outcome was classified as either excellent, good (occasional complaints, unlimited walking without aids, functional range of motion), fair (intermittent pain, ambulatory tolerance limited), or failure. There were seven excellent results, five good results, one fair result, and four failures. There were no infections, nonunions, or wound complications. At this early follow-up period, 12 (70%) of the 17 knees have been successfully treated. The authors' success rate with frozen allografts is comparable to the results of fresh allograft resurfacing. Use of frozen allografts allows time for thorough testing for viral and bacterial infections, is more practical, and the allografts are available for use in elective surgery. Failure in this series was principally the result of degeneration of the allograft's articular cartilage, or fracture of the allograft.