Prevalence and Determinants of Fatigue Following Total Knee Replacement: A Longitudinal Cohort Study.

Objective: To evaluate the prevalence and determinants of clinically important fatigue before and up to 12 months after total knee replacement (TKR) surgery.

Methods: This study was a secondary analysis of a prospective cohort study conducted among 422 patients (ages 45-74 years) undergoing primary TKR for osteoarthritis (OA) who participated in the Maximum Recovery After Knee Replacement randomized clinical trial. Assessments were carried out before, and at 6 weeks, 6 months, and 12 months after surgery. Self-reported fatigue was assessed on a 10-cm visual analog scale. Patients also completed a number of questionnaires evaluating knee pain, activity limitations, psychological well-being, comorbidity, and physical activity. Linear regression analyses were conducted to explore 6- and 12-month cross-sectional and longitudinal associations with self-reported fatigue.

Results: Clinically important fatigue (≥6.7 of 10) was reported by 145 patients (34%) before surgery, decreasing to 14%, 12%, and 8% at 6 weeks, 6 months, and 12 months after surgery, respectively. In multivariate analyses, muscle strength was strongly associated with fatigue at 6 months, and knee pain, activity limitations, number of comorbidities, and lack of energy were strongly associated with fatigue at both 6 and 12 months after TKR surgery. Female sex, number of comorbidities, depression, and fatigue were all early predictors of fatigue 12 months after TKR.

Conclusion: 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.