Prevalence and determinants of physical activity and sedentary behaviour before and up to 12？months after total knee replacement: a longitudinal cohort study

This study aims to evaluate the prevalence and determinants of inadequate physical activity and excessive sedentary behaviour before and after total knee replacement. Secondary analysis was performed on data from a cohort of 422 adults (45–74？years), drawn from 12 public or private hospitals, undergoing primary unilateral or bilateral total knee replacement surgery. Questionnaires were used to determine the presence of inadequate physical activity and excessive sedentary behaviour before and 6？ and 12？months after total knee replacement surgery. Knee pain, activity limitations, comorbidities, muscle strength, psychological well-being, fatigue, sleep and body mass index were measured/assessed as possible determinants of physical activity or sedentary behaviour. Before surgery, 77% (n？=？326) of the cohort participated in inadequate physical activity according to World Health Organization guidelines, and 60% (n？=？253) engaged in excessive sedentary behaviour. Twelve months after surgery, 53% (n？=？185) of the cohort engaged in inadequate physical activity and 45% (n？=？157) in excessive sedentary behaviour. Inadequate physical activity before surgery (P？=？0.02), obesity (P？=？0.07) and comorbidity score >6 (P？=？0.04) predicted inadequate physical activity 12？months after surgery. Excessive sedentary behaviour and activity limitations before surgery predicted excessive sedentary behaviour 12？months after 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