A Continuous Passive Motion (CPM) machine is a device used in rehabilitation to gently move a joint through a controlled range of motion. It is often prescribed following surgery or injury. Its main purpose is to prevent stiffness and help the joint regain its natural movement without requiring active effort from the user. CPM therapy is commonly integrated into post-operative care plans, particularly for individuals recovering from knee procedures.
What a CPM Machine Is
A CPM machine is a motorized therapy device designed to move a limb without patient exertion. For knee rehabilitation, it consists of a frame, a motor, and adjustable cradles that support the thigh and lower leg. These components work together to bend and straighten the knee joint repetitively and smoothly.
This continuous motion helps prevent the formation of stiff scar tissue around the joint. It also promotes improved blood circulation to the affected area, which helps reduce swelling and discomfort. By keeping the joint moving, a CPM machine can help maintain and gradually increase the knee’s range of motion.
Setting Up Your CPM Machine
Before use, place the CPM machine on a stable, flat surface, such as a bed. Plug the machine into a properly grounded electrical outlet, ensuring the cord is clear of pathways to avoid tripping hazards. Adjust the machine’s length to fit your thigh and lower leg comfortably.
Proper alignment of your knee with the machine’s hinge point is important for effective therapy and comfort. Your healthcare provider or physical therapist will provide specific instructions for initial settings, including the starting range of motion and speed, individualized to your recovery needs. Follow these prescribed settings, ensuring your hip, knee, and foot are aligned for optimal comfort and benefit.
How to Use the CPM Machine
Carefully place your leg into the machine’s cradles, aligning your knee with its pivot point. Secure your leg firmly with any provided straps, typically around the thigh and ankle, to ensure it remains in the correct position throughout the session. These straps help maintain proper alignment and prevent your leg from shifting during the passive movement.
Operate the machine using the control panel to manage the range of motion and speed. Your healthcare provider will specify the flexion (bending) and extension (straightening) limits, as well as the speed for your therapy sessions. Typically, the initial range of motion might be conservative, such as 0 to 40 or 50 degrees, and gradually increased by 5 to 10 degrees daily as tolerated. The machine will then gently move your leg through the programmed cycle, providing a gentle stretch or movement without active muscle engagement.
Tips for Safe and Effective Use
Monitor your body for discomfort during CPM sessions. While some pulling sensation may be normal as your range of motion increases, you should not experience sharp pain. If pain or tenderness occurs, stop the machine and consult your healthcare provider or physical therapist, as settings may need adjustment.
Session duration and frequency are determined by your medical professional, with common recommendations ranging from 30 minutes to several hours, often 3-4 times per day, or a total of 4 to 6 hours daily.
Contact your healthcare provider if you notice any concerning signs, such as increased swelling, redness, warmth, unusual pain in the treated leg, fever, chills, or issues with your surgical wound like increased drainage or stitches coming apart.
To maintain hygiene, ensure that the machine’s soft goods are clean, and follow any instructions for cleaning the device itself. Always keep hair, loose clothing, and body parts away from the machine’s moving components to prevent injury.