A randomized controlled trial of exercise to improve mobility and function after elective knee arthroplasty. Feasibility, results and methodological difficulties

Objective: To assess the feasibility of comparing two types of exercise regime aiming to improve mobility and function following knee arthroplasty. Design: A single-blind randomized controlled trial. Subjects: Patients with primary, unilateral knee osteoarthritis undergoing elective knee joint replacement. Intervention: Home-based traditional exercise group (TEG) or home-based functional exercise group (FEG) following discharge from hospital. Outcome measures: These included goniometry; a knee-specific pain score, leg extensor power and a walking test. Patients were followed up at three, six and 12 months after surgery. Results: Forty-seven patients met the study criteria, 24 were randomized to the TEG and 23 to the FEG. There were marked improvements in mobility, leg extensor power and pain in the year after surgery (MANOVA p < 0.001). There were no statistically significant differences between the two exercise groups. Knee flexion decreased during the follow-up period and had not recovered by 12 months. Retention of patients was a problem, with nearly 50% lost to follow-up at 12 months. These patients were assessed as having low motivation during inpatient rehabilitation ( p < 0.05). Conclusions: There were trends in favour of the FEG that were of clinical relevance. A definitive study would need a sample size of at least 100 patients in each arm. It is essential to develop strategies to combat loss to follow-up.