CPM is an abbreviation for continuous passive motion. A CPM device is a machine that is used to move a joint without the patient having to exert any effort.

A CPM machine is most commonly used on the knee joint, although there are CPM machines made for other joints as well. The CPM has a motor that bends the joint back and forth to a set number of degrees. The amount of movement of the CPM can be adjusted.

CPM machines are often applied after knee surgery, such as a knee replacement procedure. The effectiveness of CPM is debatable, as they have not been shown to offer superior results after standard surgical procedures.

Recovering normal joint mobility after surgery can be a significant challenge.  The stiffness of a joint can be a complication that limits outcomes and causes pain.  After surgery for knee replacement, ACL reconstruction, and frozen shoulder surgery, a stiff joint can be a major complication.  Therefore, some surgeons use a CPM to try to prevent scar tissue formation and improve the joint mobility.

However, there are possible downsides to using a CPM, and therefore many surgeons opt for other methods to improve joint mobility.  One of the downsides is that the machine is passive, and therefore the patient is not playing an active role in their recovery.  One of the benefits of bending your own joint is not only is the patient making gains in terms of mobility, but they are also engaging muscles around the joint that require rehab.

In most situations, CPM is not part of the standard recovery from surgery.  There are some circumstances where patients may be unable to participate in more active physical therapy, and in these situations, a CPM can be a helpful tool to use for post-surgical rehab.

It should be clear that the average patient recovering from surgery such as ACL reconstruction or knee replacement does not do better if they use a CPM.

However, there may be circumstances that make your situation different.  If you are concerned that your joint mobility is not recovering as expected, ask your surgeon if a COM device may be helpful for your recovery.

https://www.verywellhealth.com/cpm-continuous-passive-motion-2549555