Prevalence and determinants of physical activity, sedentary behaviour and fatigue five years after total knee replacement

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.