The effect of continuous passive motion duration and increment on range of motion in total knee arthroplasty patients

There is insufficient information on continuous passive motion (CPM) parameters in total knee arthroplasty patients for optimal patient outcomes. We compared CPM duration and increments on active and passive range of motion (ROM) in patients who underwent a unilateral total knee arthroplasty due to degenerative joint disease. Forty-five total knee arthroplasty patients were randomly assigned to either a control group, a short CPM duration (3-5 hours per day) group with CPM ROM increased 5 degrees twice daily, a short CPM duration group with CPM ROM increased daily to patient tolerance, a long CPM duration (10-12 hours per day) group with CPM ROM increased 5 degrees twice daily, or a long CPM duration group with CPM ROM increased daily to patient tolerance. Active and passive flexion and extension were measured goniometrically on each postoperative day that the patient was treated by physical therapy. No statistically significant differences between groups were found for baseline and final postoperative ROM. The CPM groups did not maintain the parameters assigned and were combined, revealing an enhanced rate of change of flexion. Most patients opted for a CPM duration of between 4 and 8 hours per day and the patient-preferred CPM incremental increase in ROM was 6-7 degrees/day.