Is the Incidence of Conversion from Unicompartmental to Total Knee Arthroplasty Higher Among Surgeons Who Do Not Have Arthroplasty Fellowship Training?

Abstract

Unicompartmental knee arthroplasty (UKA) may offer advantages over total knee arthroplasty (TKA) for select patients, but implant failure leading to conversion to TKA remains a concern. The purpose of this study was to compare two-year conversion rates to TKA following UKA performed by arthroplasty fellowship-trained surgeons versus surgeons who did not have arthroplasty fellowship training at a single academic institution. A retrospective review was performed of primary UKAs conducted at a single academic institution between 2010 and 2023, which had at least two years of follow-up and implant data available. Cases were grouped based on surgeon fellowship training. Demographics, operative characteristics, postoperative complications, and conversion to TKA were analyzed at two and five years, with characterization of all TKAs performed within five years. Implant survivorship was assessed using Kaplan-Meier analysis; group comparisons used Chi-square or Fisher exact tests as appropriate. A total of 413 UKAs were included, with 202 performed by arthroplasty-trained surgeons and 211 by non-arthroplasty-trained surgeons. Patients in the arthroplasty-trained group were older (mean 62.9 versus 58.5 years, P<0.001) and had higher Charlson Comorbidity Index scores (mean 5.03 versus 4.6, P<0.001). Technology utilization differed, with greater robotic use among non-arthroplasty-trained surgeons (84.4 versus 59.4%, P<0.001). At two years, conversion to TKA occurred in 2.5% of cases performed by arthroplasty-trained surgeons compared with 5.7% in the non-arthroplasty-trained group (P=0.049). Overall complication rates did not differ. Lateral UKA demonstrated significantly worse survivorship than medial UKA (log-rank P=0.0004). Among 29 TKAs performed within five years, indications and operative characteristics were similar between groups, but revision surgeon specialty differed significantly (P=0.001). Arthroplasty fellowship training was associated with a lower observed two-year conversion rate to TKA despite treatment of older, more comorbid patients and lower utilization of robotics. Failure patterns and survivorship beyond two years were similar.