Abstract
PURPOSE: We performed this retrospective study to determine the main causes for early and late failures of unicompartmental knee arthroplasty (UKA). METHODS: Between January 2000 and March 2012, all patients treated for a failed medial UKA in the authors' institution were retrospectively reviewed. A total of 471 patients were identified, and causes of failure were analysed based on the medical records and radiographs at the time of revision. RESULTS: The cohort included 161 males and 310 females, with a mean age of 67.7 years (range, 42-91 years; SD = 10.1) at the time of revision. The mean time from index arthroplasty to revision surgery was 6.1 years (range, 0.1-27.9 years; SD = 5.6). A total of 254 cases (53.9 %) failed within five years after primary implantation, and 108 cases (22.9 %) failed after ten years. The major reason for failure was the development of other compartment arthritis (39.5 %), followed by aseptic loosening (25.4 %). CONCLUSIONS: Of importance, the mean time to failure after UKA was 6.1 years, with more than 50 % of failures occurring within the first five years postoperatively.