Continuous passive motion (CPM) is a postoperative therapy approach that uses a machine to move the knee continuously through a specific range of motion, with the goal of preventing joint stiffness and improving recovery. There is no evidence that CPM therapy leads to a clinically significant improvement in range of motion, pain, knee function, or quality of life. CPM is inexpensive, convenient, and assists patients in therapeutic compliance. However, CPM should be used in conjunction with traditional physical therapy. In unusual cases where the person has a problem which prevents standard mobilization treatment, then CPM may be useful.