The Useful Continuous Passive Motion (CPM)

Overview

Continuous passive motion (CPM) is one of the primary methods for decreasing the deleterious effects of immobilization and can deliver orthopedic, neurological, and even circulatory benefits to the patient. Immobilization, in turn, can create deleterious sequelae of physiological and functional impairments.

CPM is used following various types of reconstructive joint surgery such as knee replacement and ACL reconstruction. Its mechanisms of action for aiding joint recovery are dependent upon what surgery is performed. One mechanism is the movement of synovial fluid to allow for better diffusion of nutrients into damaged cartilage (which would be unimportant in the event of joint replacement), and diffusion of other materials out; such as blood and metabolic waste products. Another mechanism is the prevention of fibrous scar tissue formation in the joint, which tends to decrease the range of motion for a joint. The concept was created by Robert B. Salter M.D in 1970 and, along with help from engineer John Saringer, a device was created in 1978.

CPM evolved over the course of several decades, and is based on deductions that the inventor formulated through clinical observation and practice. The first of these is that prolonged immobilization of synovial joints causes many problems, including persistent stiffness and pain, muscle atrophy, disuse osteoporosis, and eventually degenerative arthritis when the joints are actively mobilized at a later time. Second, beneficial effects of early active motion were seen clinically, such as decreased edema, decreased pain, and shorter rehabilitation time.

Finally, observations of cardiac surgery wherein the heart muscle heals properly in the presence of constant motion, and in the costovertebral joints, where constant motion occurs throughout the life of the individual, yet where degenerative arthritis is rarely seen, led the inventor to pursue CPM development.

The use of CPM

Applied postoperatively, this device may be used on an inpatient or an outpatient basis. By using a motorized device to very gradually move the joint, it is possible to significantly accelerate recovery time by decreasing soft tissue stiffness,increasing range of motion, promoting healing of joint surfaces and soft tissue, and preventing the development of motion-limiting adhesions (scar tissue). Interestingly, this is accomplished without patient effort (passively) as the machine moves ajoint through a defined (prescribed) range of motion for an extended period of time. Even more surprisingly, studies have shown that patients using CPM devices require less pain medication then patients who have had the same type of surgery and are notusing this device.
Within 24 hours of surgery your doctor can initiate the CPM machine.The machine will be used on your new knee at least 4 hours during the day and all night. You will continue this program when you go home.

The fuction of CPM

CPM would accelerate the healing of articular cartilage and periarticular structures, such as the joint capsule, ligaments, and tendons. CPM would decrease the likelihood of joint contractures, therefore maintaining the range of motion(ROM) achieved during surgery. CPM has been shown to significantly increase venous flow over active and passive ankle dorsiflexion, pneumatic compression, and manual calf compressions. The CPM machine has many advantages. The machine administers controlled, passive motion, which increases blood flow to the joint. The increased blood brings nutrition to the joint, and helps to alleviate swelling.The CPM machine increases flexibility in the joint and shortens the time of hospital stay.