One hundred and one unicompartmental knee arthroplasties (UKA) were done between 1996 and 2000 with ALPINA(®) UNI, a cementless hydroxyapatite-coated anatomic prosthesis. Sixty-five knees were available for the long-term follow-up at a mean of 11 years. The mean IKS improved from 119.3 ± 16.8 points preoperatively to 171.4 ± 25.3 at the latest follow-up (p < 0.0001). Eighty-nine percentage of the knees were rated good and excellent. The mean knee flexion has significantly improved from 120°5 preoperatively to 127°3 at the latest follow-up (p < 0.01). Eleven revision procedures were done: 1 for early knee degeneration on rheumatoid arthritis, 1 for degeneration of osteoarthritis in the opposite compartment of the knee, 1 for unexplained pain and 1 for late ACL rupture, all these 4 cases were replaced by total knee arthroplasties; 3 revisions by another UKA were done due to polyethylene insert fracture; and 4 partial revision were done for bearing exchange due to severe polyethylene wear. When revision for any reason was defined as the end point, the 13-year Kaplan-Meier survival rate was 88 % (95 % CI 81-95 %) and when revision due to implant mechanical failure (excluding degeneration of osteoarthritis in the opposite compartment of the knee and bearing exchange only) was defined as the end point, the 13-year survival rate was 94 % (95 % CI 89.1-99.1 %).

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