Sex does not clinically influence the functional outcome of total knee arthroplasty but females have a lower rate of satisfaction with pain relief

BACKGROUND: The aims were to assess whether sex had a clinically significant independent influence on the outcome of total knee arthroplasty (TKA) according to the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, Short Form (SF-) 12 scores and patient satisfaction at 1 year. METHODS: A retrospective cohort of 3510 primary TKA were identified. Patient demographics, comorbidities, WOMAC and SF-12 scores were collected preoperatively and 1 year postoperatively. Patient satisfaction were assessed at 1 year. RESULTS: There were 1584 males and 1926 females. The preoperative WOMAC and SF-12 scores were significantly (p < 0.001) worse in females but were not greater than the minimal clinically important difference (MCID). When adjustments had been made for confounding differences, females showed a significantly greater improvement in their function (1.5 points, p = 0.03) and total (1.5 points, p = 0.03) WOMAC scores compared to males, but these were not greater than the MCID. When adjustments had been made for confounding differences, females were less likely to be satisfied with their pain relief (p = 0.03) relative to males. CONCLUSION: Sex does not clinically influence the knee specific outcome (WOMAC) or overall generic (SF-12) health 1 year after TKA. However, satisfaction with pain relief after TKA was significantly less likely in female patients. LEVEL OF EVIDENCE II: Prognostic retrospective cohort study.