Long-Term Trajectories of Patient-Reported Outcomes Following Total Knee Arthroplasty: A Longitudinal Study of 1,264 Patients.

backgroundAlthough total knee arthroplasty (TKA) is known to improve patient-reported outcome measure (PROM) scores in the short term to midterm, the long-term trajectories of both disease-specific and generic PROM scores remain unclear.

methodsWe retrospectively analyzed the prospectively collected registry data of 1,264 patients (mean age, 68.5 years; 93.7% female) who underwent primary TKA for osteoarthritis between 2005 and 2013 and completed PROM assessments at baseline and 10 years postoperatively. Disease-specific PROMs were assessed using the Knee Society Knee Score (KSKS), Knee Society Function Score (KSFS), and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Generic PROMs were assessed using the Short Form-36 Health Survey (SF-36). Assessments were performed preoperatively and at 6 months and 1, 2, 5, 10, and 15 years postoperatively. Generalized linear models and linear mixed-effects models were used to evaluate temporal changes and subgroup differences by age and sex.

resultsAll PROM scores improved significantly within 6 months after TKA. Thereafter, disease-specific PROMs showed modest changes up to 1 year, with relative stability until 5 years, whereas generic PROMs demonstrated heterogeneous patterns across different domains. Between 5 and 10 years postoperatively, WOMAC pain and stiffness scores did not show significant changes, the KSKS decreased but not significantly so, and WOMAC physical function scores exhibited small but significant deterioration that was not clinically meaningful. SF-36 domains demonstrated varied trajectories: physical and mental component scores declined by more than the minimal clinically important difference after 5 years, whereas the social functioning score showed continuous improvement, although not all changes were significant. Octogenarians demonstrated lower physical functioning scores but higher social functioning scores in the long term compared with younger patients, and female patients demonstrated inferior functional and vitality scores compared with male patients.

conclusionsBoth disease-specific and generic PROM scores after TKA improved significantly and remained superior to baseline scores over a 15-year period, although physical function scores tended to decline in the long term. In this large, predominantly female Korean cohort, the distinct age- and sex-specific trajectories highlight the importance of implementing individualized, time-adapted long-term management strategies to optimize patient outcomes. LEVEL OF EVIDENCE: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.