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 knee 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.