From the Guidelines
Continuous passive motion (CPM) is not recommended for routine use in rehabilitation protocols due to its lack of additional benefits for pain, range of motion, or swelling compared to active motion exercises, and its time-consuming and costly nature.
Definition and Purpose of CPM
Continuous passive motion (CPM) is a postoperative treatment method that uses a mechanical device to move a joint through a predetermined range of motion without patient effort. The theoretical benefits of CPM include improved cartilage healing, prevention of joint adhesions, reduced swelling, and enhanced range of motion by maintaining continuous synovial fluid movement across joint surfaces.
Current Evidence and Recommendations
However, current evidence does not strongly support routine CPM use for most orthopedic procedures. A recent study published in the British Journal of Sports Medicine in 2023 1 found that there is no additional benefit for pain, range of motion, or swelling in using continuous passive motion compared with active motion exercises. The study recommends against using CPM in the rehabilitation protocol as it is time-consuming and costly. Another study published in the same journal in 2020 1 also recommends that continuous passive motion should not be used in the rehabilitation of patients after ACL reconstruction.
Clinical Considerations
While CPM may still benefit select patients with limited mobility, those at high risk for joint stiffness, or cases where active movement is contraindicated, modern rehabilitation protocols emphasizing early active mobilization and physical therapy have largely replaced CPM as standard care. The benefits of CPM are largely theoretical, and most patients achieve comparable outcomes with standard physical therapy alone, making CPM an adjunctive rather than primary rehabilitation strategy in contemporary orthopedic practice. A study published in 2023 1 found that there was no difference reported in knee range of motion, pain, and swelling when CPM was compared with active knee motion exercises, further supporting the recommendation against routine use of CPM.
Key Points to Consider
- CPM is not recommended for routine use in rehabilitation protocols
- CPM has no additional benefits for pain, range of motion, or swelling compared to active motion exercises
- CPM is time-consuming and costly
- Modern rehabilitation protocols emphasize early active mobilization and physical therapy
- CPM may still benefit select patients with limited mobility or those at high risk for joint stiffness.
From the Research
Definition and Purpose of Continuous Passive Motion (CPM)
- Continuous Passive Motion (CPM) is a method used in the early post-operative rehabilitation of patients after knee surgery 2, 3, 4, 5, 6.
- CPM is designed to maintain or improve range of motion in the affected joint by moving the joint through a controlled range of motion without the patient's active participation 3, 4.
- The primary goal of CPM is to prevent stiffness and promote healing in the joint by pumping blood and edema fluid away from the joint and periarticular tissues 3.
Clinical Applications of CPM
- CPM has been used in various clinical settings, including post-operative rehabilitation after total knee arthroplasty 2, 5, 6, elbow rehabilitation 3, and pediatric orthopedics 4.
- CPM can be used in conjunction with physical therapy to enhance rehabilitation outcomes 2, 5, 6.
- The effectiveness of CPM in improving clinical measurements, such as range of motion and functional ability, has been debated in the literature 2, 5, 6.
Key Findings and Controversies
- Some studies have found that CPM can improve subjective assessments of pain level, joint stiffness, and functional ability 2, while others have reported no significant differences in clinical measurements between CPM and control groups 2, 6.
- The optimal duration and frequency of CPM sessions, as well as the total period of CPM application, are still unclear and require further research 5.
- CPM may be beneficial for patients undergoing bilateral knee replacement, but its effectiveness in patients with single knee replacement is less clear 6.