Modes of failure and revision of failed lateral unicompartmental knee arthroplasties

Even with the resurgence of interest in unicompartmental knee arthroplasty (UKA) in recent years, lateral UKA is still performed 10 times less frequently than medial UKA. Hence, because of the infrequency of this procedure, a paucity of outcome studies exist on lateral unicompartmental knee arthroplasty. This retrospective study was performed to analyze the main causes of failure, as well as the time to failure following lateral UKA.

A total of 16 consecutive failed lateral UKAs were revised at our institution and were retrospectively reviewed. Causes of failure and time to failure were analyzed based on the medical records and radiographs at the time of revision.

The mean time from index arthroplasty to revision surgery was 9.4 years. In three cases, lateral UKA was converted to primary TKA and in the remaining thirteen cases, revision knee joint systems were used. Seven out of the 16 patients (43.8%) were revised within five years after the index surgery. Overall, the most common reason for failure was progression of arthritis of the medial and/or patellofemoral compartments (56.3%) followed by aseptic loosening (18.8%).

In conclusion, similar to published reports on medial UKA, the main reason for early and late failure after lateral UKA was progression of arthritis in other compartments.

IV