Using at least 20% medial unicompartmental knee arthroplasty is associated with improved patient-reported outcome measures across all knee arthroplasty patients.

Purpose: To investigate the impact of orthopaedic surgeons' arthroplasty distributions on patient-reported outcome measures (PROMs) following knee arthroplasty, thus addressing the gap in knowledge regarding the optimal distribution of arthroplasties.

Methods: 2256 knee arthroplasties were included (total knee arthroplasty [TKA] or unicompartmental knee arthroplasty [UKA]). All were conducted at a single centre between August 2016 and August 2022 with a minimum of 1-year follow-up. The Oxford Knee Score (OKS), the Forgotten Joint Score (FJS) and the Activity and Participation Questionnaire (APQ) were assessed preoperatively, and at 3 and 12 months postoperatively. Patients were categorized based on the surgeons' yearly surgeries: (1) TKA only, (2) TKA+ <20% medial UKA, (3) TKA+ ≥20% medial UKA and (4) TKA+ ≥20% medial UKA + lateral UKA + patellofemoral UKA. Linear regression models adjusted for demographic variables and preoperative PROM scores were used to estimate changes in mean PROM scores.

Results: Group 4 showed significantly higher improvements in PROM scores at 3 and 12 months compared to Group 1. In the 12-month adjusted analysis, Group 4 had 1.9 points (95% confidence interval [CI]: 1.0-2.8) higher OKS-, 7.0 points (95% CI: 3.9-10.2) higher FJS- and 8.3 points (95% CI: 4.8-11.8) higher APQ-change than Group 1. There were no significant differences between Groups 1 and 2, nor any clinically relevant differences between Groups 3 and 4. Additionally, the percentage of patients who achieved excellent OKS (>41) was significantly higher in Groups 3 + 4 compared to Groups 1 + 2 (p < 0.001).

Conclusion: Despite limitations, the findings of this study suggest that utilizing ≥20% medial UKA leads to greater postoperative improvements in PROM across all treated knee arthroplasty patients.

Level of evidence: Level III.