Revision of Unicompartmental Knee Arthroplasty Results in Outcomes Similar to those of Primary Total Knee Arthroplasty and Superior to those of Revision Total Knee Arthroplasty

The main aim of this study was to analyze whether revision of medial unicompartmental knee arthroplasty (rUKA) has better clinical outcomes than primary total knee arthroplasty (TKA) or revision of total knee arthroplasty (rTKA). The study reference group (rUKA) was identified and matched with two control groups: primary TKA and revision rTKA. Patients were matched according to five preoperative factors: follow-up (minimum of 60 months), age, sex, body mass index (BMI), and operation side at a ratio of 1:1:1. The Knee Society score (KSS) and the forgotten joint score (FJS) were used for the clinical assessment. The pain was measured via the visual analog scale (VAS) for pain. The following complications were also recorded: postoperative anemia, infection, and revision surgeries. Forty-five patients were included in each group. The three groups did not differ in terms of age, sex, operation side, BMI, or follow-up (p > 0.05). At the final follow-up, the rTKA group had lower values than did the rUKA and TKA groups in terms of the KSS (rUKA = 95; TKA = 100; rTKA = 87.5) and FJS (rUKA = 95; TKA = 100; rTKA = 90; p < 0.05). For the KSS, no difference was found between the rUKA and TKA groups (p > 0.05). Regarding pain, the rTKA group had a lower value than the TKA group did (p = 0.001; rUKA = 3; TKA = 2; rTKA = 3), whereas in terms of FJS, there was also a difference between the rUKA and TKA groups (p = 0.038). The rates of complications in terms of postoperative anemia and aseptic loosening were similar among the three groups (p > 0.05). Revised UKA has comparable clinical and patient-reported outcomes to those of primary TKA and better outcomes than those of revised TKA, whereas medical complications of revised UKA are similar to those of primary TKA. These findings serve to inform discussions with patients requiring revision of a UKA regarding clinical outcomes and complications following this procedure. The level of evidence is a level III match cohort study.