Among patients undergoing TKR for OA, clinically important fatigue is considerably prevalent both before and for at least 6 months after surgery. Identifying and addressing early predictors of ongoing fatigue has the potential to improve the quality of life following TKR surgery.

Although there were improvements after total knee replacement, 12 months after surgery about half the cohort did not meet World Health Organization recommendations for activity. Pre-surgery assessment of physical activity, activity limitations, sedentary behaviour and body mass index is essential to identify patients at risk for long-term inactivity.

Objective To determine the prevalence and predictors of physical activity, sedentary behaviour and fatigue five years after total knee replacement surgery. Design A longitudinal cohort study. Setting Community-dwelling adults who had previously undergone total knee replacement. Methods Five-year follow-up questionnaire data were obtained from participants previously enrolled in a randomised controlled trial examining rehabilitation after total knee replacement. Main study outcomes at one year did not differ between randomisation groups, hence data were pooled for the present longitudinal analysis. Before and one and five years after surgery, participants completed questionnaires (Active Australia Survey, WOMAC, SF12 v2, demographics and fatigue). Results 272/422 community-dwelling adults (45–74 years) completed the questionnaires at five years. Excessive sedentary behaviour was evident in 91% of the cohort, predicted by excessive sedentary behaviour and lack of energy at one year. Inadequate physical activity at five years was evident for 59% of the cohort, predicted by higher fatigue and comorbidity scores pre-surgery and inadequate physical activity at one year. Just under half (47%) of the cohort experienced clinically-important fatigue at five years, predicted by clinically-important fatigue before and one year after surgery, lack of sleep before surgery and physical activity one year after surgery. Conclusion Documenting physical activity, sedentary behaviour and fatigue before and one year after knee replacement is important to identify those at risk of longer-term inadequate physical activity, excessive sedentary behaviour and clinically-important fatigue. Interventions to maintain activity and reduce sedentary behaviour are needed to reap the potential health benefits of total knee replacement surgery.