Incidence of suboptimal femoral component sizing in Oxford Unicompartmental Knee Arthroplasty and comparisons for patient-reported outcomes with the optimal group: A retrospective cohort study in Taiwan

Abstract

Abstract Background: The Oxford Unicompartmental Knee Arthroplasty (OUKA) is a reliable surgical procedure for anteromedial osteoarthritis of the knee. However, in Taiwan, the incidence and patient-reported outcomes in suboptimal femoral component sizing remain unclear. Therefore, we conducted this study to clarify these issues. Methods: We identified all patients receiving OUKA in a Taiwan medical center between May 1, 2018, and August 31, 2021, for this study. Age, sex, height, weight, body mass index, preoperative and postoperative Knee Society Score (KSS) functional activity score, and postoperative range of motion (ROM) and numeric rating scale (NRS) were included. Optimal and suboptimal groups were classified based on the posterior fit of the femoral component on postoperative lateral radiography. Outcome comparisons were performed between the two groups after following up. Results: Ninety-two patients (111 knees) were included in the study, including 79 (71.2%) knees in the optimal group and 32 (28.8%) knees in the suboptimal group. The median age was 68 years and 67 years, and the percentage of the male sex was 17.7% and 37.5% in the optimal and suboptimal groups, respectively. Compared with the suboptimal group, there was a greater improvement in KSS functional activity score in the optimal group; however, the difference was not significant (40 vs. 34, p = 0.154). Nonsignificant differences were also found between the two groups in the postoperative KSS functional activity score and the postoperative NRS and ROM. Conclusions: This study delineated the incidence and patient-reported outcomes in suboptimal femoral component sizing after OUKA in Taiwan, which provides an important reference for clinicians. Further studies, including more patients, are needed for validation.