Unicompartmental knee arthroplasty. A 4.5-6-year follow-up study with a metal-backed tibial component.

The results in the first 50 patients to receive an improved-design unicompartmental knee prosthesis were reviewed after an average follow-up period of 5.5 years. The prosthesis is composed of a metal-backed polyethylene tibial component and a wide femoral surface replacement that are fixed to bone with acrylic cement. Forty-five patients with 55 unicompartmental knee arthroplasties were available for clinical study. Ninety-two percent of the knees were rated as having a good or excellent result, and 94% had lasting relief of pain. There have been no failures requiring revision. A radiographic review demonstrated that no tibial component was bordered by a complete radiolucent line. There was no subsidence or loosening of either the tibial or femoral components, and there was no instance of local osteolysis. These results, coupled with a 14-year follow-up experience with the original-design unicondylar prosthesis, encourages the authors to remain advocates of this procedure in selected patients with unicompartmental osteoarthritis.