CLOSING THE GAP: SEX-BASED DIFFERENCES IN PATIENT-REPORTED OUTCOMES, FUNCTIONAL RECOVERY, RANGE OF MOTION, AND EARLY REVISION AFTER PRIMARY TOTAL KNEE ARTHROPLASTY

Abstract

Background: Total knee arthroplasty (TKA) provides substantial pain relief and functional improvement in end-stage knee osteoarthritis, but recovery varies between patients. Reported sex differences may reflect biological effects, differences in preoperative disease burden, or both. We modelled whether sex would remain associated with early outcomes after adjustment for baseline status. Methods: A dataset of prospective observational cohort: 205 adults undergoing primary TKA for osteoarthritis between 1st July 2024 to 1st July 2025, assessed preoperatively, at 6 weeks, and at 3 months. The cohort comprised 103 women and 102 men. Outcomes were Oxford Knee Score (OKS), Knee injury and Osteoarthritis Outcome Score (KOOS), WOMAC, visual analogue scale (VAS) pain, and knee range of motion (ROM). The primary analysis used multivariable linear regression for 3-month OKS adjusted for baseline OKS, age, BMI, Charlson comorbidity index, and diabetes. Results : Women had lower baseline OKS (17.5 (5.5) vs 21.1 (6.1)) and KOOS (39.1 (10.3) vs 43.1 (10.3)), with higher WOMAC (63.5 (12.8) vs 58.4 (11.1)). Both groups improved substantially. At 3 months, mean OKS was 36.0 in women and 39.3 in men. After adjustment, female sex was associated with a-0.19 point difference in 3-month OKS (95% CI-1.07 to 0.70; p=0.677). A >=5-point OKS improvement occurred in 100.0% of women and 100.0% of men. Interpretation: In this analysis, women reached surgery with worse symptoms but achieved large early gains. The crude sex difference was substantially attenuated after baseline adjustment, suggesting that preoperative disease burden and patient characteristics may explain much of the apparent early disparity.