Electromyographic evaluation of continuous passive motion versus manual rehabilitation of the temporomandibular joint

There have been a myriad of rehabilitation techniques for patients after temporomandibular joint (TMJ) surgery, varying from professionally delivered physical therapy to self use of tongue blades. Most recently continuous passive motion (CPM) has been introduced for postsurgical TMJ patients. The benefits of CPM have been attributed both to its continuous and its passive nature. While the continuous nature of the therapy is accepted, questions remain regarding the passivity of the motion. The purpose of this study was to electromyographically evaluate the degree of activity that occurs with CPM compared with simple mandibular exercises in TMJ rehabilitation. Eight patients who had arthroscopy or arthrotomy were begun on a CPM device postsurgically. Electromyographic data were obtained for jaw closing and opening activity. Patients were measured using CPM as well as tongue depressors. Three different exercises were performed: 1) activity at rest was compared with rest with CPM; 2) opening and closing with CPM versus use of tongue depressors was compared; and 3) maximum opening to a comfortable position was compared using tongue depressors versus the CPM device in a fixed open position. The degree of opening was matched for both groups. A significant difference in electromyographic activity was shown between patients using CPM versus tongue depressors during the open/closing cycles. This suggests that TMJ CPM is truly passive.