Revision of unicompartmental arthroplasty of the knee. Clinical and technical considerations.

In 73 unicompartmental arthroplasties of the knee that were revised, the major causes of failure were progression of arthritis and implant failure. The interval between the primary and revision averaged 56 months. Eighty-eight percent were revised to a variety of total condylar prostheses. Bone loss was classified by defect at the end of preparation. In 31 patients, there were none; in 17, the defect was in either the femur or the tibia; and in 25, there were defects in both the femur and the tibia. Forty-seven of these defects were small and contained, presenting little problem. Twenty defects were either large, contained, or peripheral, requiring reconstruction. Fifteen knees were lost as a result of death (but there had been satisfactory knee function); 2 were lost to follow-up evaluation, and 3 have required further revision. Seventy-nine percent of the surviving knees had excellent or good knee function at an average follow-up period of 56 months.