Physical activity after unicompartmental knee arthroplasty: Long-term participation, activity volume and patient-reported limitations.

Purpose: To characterize long-term patient-reported sports and physical activity after unicompartmental knee arthroplasty (UKA), including participation, weekly volume, perceived exertion, time to resumption, limitations, satisfaction and sex-based differences. Methods: This retrospective single-institution study included 150 patients who underwent primary UKA between 2014 and 2022. An 11-item electronic questionnaire administered in 2025 assessed activity at 5 years before UKA, 1 year before UKA, 1 year after UKA and at current follow-up. Current participation was the primary outcome. Historical responses were treated as retrospectively recalled estimates. Mean follow-up was 6.8 ± 2.4 years. Results: Of 190 contactable patients, 150 responded (78.9%). Mean age was 65.1 ± 10.9 years. Participation was recalled by 33.3% at 5 years before UKA, 8.0% at 1 year before UKA and 25.3% at 1 year after UKA; 33.3% reported current participation. Among current participants, 74.0% reported >3 h/week and 48.0% reported moderate-or-higher exertion. Overall, 49.3% resumed activity within 12 months, 42.0% perceived improvement and mean satisfaction was 3.84 ± 1.30. Activity-related limitations and long-term restrictions were reported by 75.3% and 30.0%, respectively. Most outcomes were similar between women and men; the fully adjusted association between male sex and improved intensity was not significant (adjusted odds ratio 2.08, 95% confidence interval 0.90-4.80). Conclusions: At long-term follow-up after UKA, one-third of patients reported current sports or physical activity participation, and most current participants reported >3 h/week. However, only half resumed activity within 12 months, and residual limitations were common. Historical group-level proportions should not be interpreted as individual return to activity or longitudinal recovery. Level of Evidence: Level IV.