Continuous passive motion in the rehabilitation setting. A retrospective study.

Continuous passive motion (CPM) has been commonly used in the postoperative rehabilitation of patients after total knee arthroplasty. In the acute care hospital, most studies have found CPM to be useful in improving range of motion and reducing length of stay. The benefit of CPM in the rehabilitation hospital has not been studied. The charts of 61 patients who had undergone total knee arthroplasty and subsequently were admitted to the East facility of the Kessler Institute for Rehabilitation were reviewed. Patients were separated into two groups: Group 1 received CPM for 3 to 4 hours/day and physical therapy for 2 hours/day. Group 2 received only physical therapy. There was no significant difference in passive range of motion or length of stay between Group 1 and Group 2. An analysis of the 16 patients who underwent bilateral replacement was undertaken. Patients in Group 1 (n = 7) achieved an average increase in passive range of motion of 20.1 degrees, whereas those in Group 2 (n = 9) achieved an increase of 12.7 degrees (P = 0.18). Power analysis demonstrated the need for 50 patients per subgroup to achieve significance. The lack of statistical significance in this subgroup may be a reflection of the small study population (n = 16). The following conclusions can be drawn concerning the use of CPM in the rehabilitation setting: (1) CPM was of no added benefit to those patients admitted after single knee replacement, and (2) CPM may be beneficial to those patients admitted after bilateral knee replacement.