RecruitingDevice studyContinuous Passive Motion Following Fixation of Pelvic and Knee FracturesThe investigators will directly compare the visual analog scale scores and narcotic pain medication requirements in the patients who have continuous passive motion (CPM) versus those who do not during the course of the hospital admission following an open reduction internal fixation surgery for acetabular fracture, supracondylar femur fracture, or a tibial plateau fracture.