81 patients with osteoarthritis undergoing primary total knee arthroplasty (TKA) were randomised to undergo one of three postoperative in-hospital rehabilitation interventions. The patients underwent either a conventional physical therapy with 35 minutes of continuous passive motion (CPM) daily, conventional physical therapy with 2 hours of CPM daily, or conventional physical therapy only. The primary outcome was active range of motion (ROM) in knee flexion. Results indicated that no significant difference in the outcomes were observed in the three groups at the time of discharge, indicating that the inclusion of CPM in addition to conventional physical therapy may not be advantageous.