Total knee arthroplasty (TKA) is a common form of orthopedic surgery that can improve the quality of life for patients. Patients who receive joint replacement are particularly susceptible to developing deep vein thrombosis and pulmonary embolism following the surgery because of tissue damage, surgical stress and immobility and muscle weakness. Venous thromboembolism describes both deep venous thrombosis (DVT) and pulmonary embolism (PE), which is potentially fatal. The risk of DVT is greatest in the first week after surgery. Drug treatments to prevent venous thromboembolism include low-molecular-weight heparin, fondaparinux, or warfarin, which reduce blood clotting (coagulation). These drugs increase the risk of bleeding after TKA and associated complications such as infection and wound healing problems. Early mobilisation and mechanical methods are therefore of clinical interest. Continuous passive motion (CPM) uses an external motorised device to move the knee for the patient through a preset range of motion as part of postoperative management.
This review did not find enough evidence from randomised controlled trials to conclude that CPM reduces VTE. We included 10 trials involving 764 participants in our review. The incidence of DVT or venous thromboembolism was not clearly different in the CPM group compared with the control group of participants
The methodological quality of the included studies was variable. Sensitive methods such as venography or sonography were not always used to diagnose DVT and the CPM was applied differently across studies, varying in range of motion, duration of CPM per day and the number of days after the surgery.