Common causes of failed unicompartmental knee arthroplasty: a single-centre analysis of four hundred and seventy one cases

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.

Fig. 1

Time interval distribution of failed unicompartmental knee arthroplasties (UKAs). More than 50 % of the failures occurred within five years of primary arthroplasty

Fig. 2

Distribution of body mass index (BMI) for failed unicompartmental knee arthroplasties (UKAs) at the time of revision surgery. Less than 10 % of patients had a BMI greater than 35 kg/m²

Fig. 3

Femoro-tibial angles for failed unicompartmental knee arthroplasty (UKA) due to development of other compartment arthritis and for all other causes of failure. There were no significant differences in coronal plane deformity between groups

Fig. 4

Age distribution at the time of index surgery