Incidence of Reoperation and Reasons for Reoperation after Minimally Invasive Unicompartmental Knee Arthroplasty

The goal of this report is to review reoperations undertaken within the first 3 years of the initial 221 unicompartmental arthroplasties performed using a minimally invasive technique and the same component design. A comparison was then performed between these cases and the 514 medial unicompartmental arthroplasties performed with an open exposure over the prior 17 years. In the minimally invasive group, 9 (4.1%) of 221 knees were revised (8 for component loosening, 1 for deep infection). Of 212 unrevised knees, 16 have required a total of 18 nonrevision reoperations. Overall, 25 of 221 knees required at least one reoperation (total reoperation rate: 11.3%). By comparison, the historical open exposure group had 35 (6.8%) of 514 knees that required revision, 10 (1.9%) of 514 knees that required a nonrevision reoperation, and total reoperation rate of 45 (8.6%) of 514. While most of these reoperations were due to excessively shelf-aged polyethylene, the revision rate due to aseptic loosening was 5 (1.0%) of 514. Despite an accelerated recovery and decreased hospital stay in our minimally invasive unicompartmental arthroplasties, the rate of revision due to aseptic loosening (3.7% vs 1.0%) and the overall reoperation rate (11.3% vs 8.6%) compare unfavorably to those performed with an open technique. Familiarity with the concerns related to the minimally invasive technique may help reduce the need for reoperation while maintaining benefits of less invasive approaches.