Unicompartmental arthroplasty for osteonecrosis of the knee joint.

A review of 34 knees with osteonecrosis of the medial femoral condyle treated by unicompartmental arthroplasty is presented, with a minimum of two years' follow-up time and an average of five-and-one-half years. Excellent or good results were obtained in 89% of the patients. Of the four failures reported, two were caused by the development of osteonecrosis of the lateral compartment. Two other patients had persistent pain with no apparent cause. Unicompartmental arthroplasty is acceptable treatment of osteonecrosis of the knee joint because of the rapid recovery from the operation, the low morbidity rate, and the preservation of the cruciate ligaments, the patella, and the opposite compartment, which results in better function and motion than a high tibial osteotomy or a total knee arthroplasty.