WOMAC-based recovery after total knee arthroplasty in a multiethnic Asian cohort: a 5-year registry-based study of interval-specific predictors of improvement.

BACKGROUND

Patient-reported outcomes (PROs) after total knee arthroplasty (TKA) are well-documented in Western populations, but long-term recovery and its determinants in multiethnic Asian populations remain poorly understood. We aimed to characterise 5-year WOMAC recovery after TKA and to identify patient, clinical, and surgical factors associated with the odds of improvement at each consecutive postoperative interval in a multiethnic Asian cohort.

METHODS

This registry-based cohort study used prospectively collected data from a tertiary hospital in Singapore. We included 4964 consecutive cases with osteoarthritis undergoing primary TKA between December 1, 2008, and December 31, 2023. The primary outcomes were changes in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) total and subscale scores, measured at baseline and at 6 months, 1, 2, and 5 years postoperatively.

RESULTS

The mean (SD) total WOMAC score improved from 38.6 (15.1) at baseline to 7.5 (9.2) at 5 years. The greatest improvement occurred within the first 6 months (mean change, 27.6 points; P value < .001). In multivariable interval-specific analyses, older age (≥ 75 years; OR 0.55, 95% CI 0.39-0.79) and the presence of one or more comorbidities (OR 0.83, 95% CI 0.71-0.96) were independently associated with lower odds of long-term improvement. Interval-specific associations with ethnicity were also observed for pain and stiffness.

CONCLUSIONS

In this large, multi-ethnic Asian cohort, TKA was associated with substantial and durable WOMAC improvements, primarily within the first 6 months. Interval-specific predictors of improvement were dominated by patient-level factors, notably age, comorbidity, and ethnicity, while surgical variables showed limited association. These findings support the potential value of patient-centred risk stratification and culturally responsive perioperative care in optimising long-term outcomes.