Physical Function Following Total Knee Arthroplasty for Osteoarthritis: A Longitudinal Systematic Review With Meta-Analysis

OBJECTIVES: To explore the extent of functional improvement following primary total knee arthroplasty for knee osteoarthritis and compare trajectories of self-reported and performance-based measures of physical function. METHODS: We searched three electronic databases from January 2005 to February 2023 for longitudinal cohort studies involving adults with knee osteoarthritis undergoing primary total knee arthroplasty. Estimates of self-reported and performance-based physical function were extracted pre-surgery and up to five-years post-surgery. Risk of bias was assessed using a six-item checklist. Self-reported function scores were converted to a 0-100 scale (higher scores indicate worse function). Mixed models provided pooled estimates after excluding low-quality studies. RESULTS: Out of 230 relevant studies, 72 (n=19,063) of not low-quality were included in meta-analyses. Self-reported function significantly improved from pre-surgery (55.6/100, 95% CI 53.1 to 58.1) to 3-6 months post-surgery 21.1 (95% CI 17.9 to 24.3) (p < 0.001). A small decline in self-reported function occurred at 6-12 months (31.0, 95% CI 25.8 to 36.2) (p < 0.001), with no further change at 12-24 months (30.9, 95% CI 23.2 to 38.6) (p = 0.919). Performance-based measures exhibited variable trajectories, with most estimates indicating no clinically meaningful improvement following total knee arthroplasty. CONCLUSION: Total knee arthroplasty resulted in clinically meaningful improvements in self-reported function at 3-6 months post-operatively. There was some deterioration in function after 6 months, and at no other timepoint did the estimate reach a clinically important change. There was limited evidence of clinically meaningful improvements in performance-based measures of physical function at any time point.