A continuous passive motion (CPM) machine allows for movement of the joints after surgery. A person may use a CPM machine after undergoing surgery on joints such as the knee or hip.
Some people may find that a CPM machine helps increase range of motion, though research is unclear about whether or not they provide any significant benefits for recovery.
For this reason, a person should not be surprised if their doctor or surgeon does not suggest using this device.
Keep reading to learn more about how a CPM machine works, the potential benefits for use on different joints, and how a person can get a CPM machine for home use.
A CPM machine is a piece of equipment that a person may use to help with recovery after undergoing joint surgery. The idea behind CPM machines is that they increase range of motion.
They provide sessions of continuous motion for joints that a person is unable to move freely.
People may experience pain when trying to move their joint after undergoing surgery. This can cause them to avoid moving the joint, which can result in stiffness, a loss of motion, and the development of scar tissue.
People may use a CPM machine after undergoing surgery to increase a joint’s range of motion.
Some research suggests that a CPM machine could:
- reduce pain
- reduce the length of hospital stays
- reduce the need for manual movement of the joint while people are under anesthetics
However, the study authors conclude that there was insufficient evidence to determine the effect of a CPM machine on participants’ global assessment of treatment effectiveness.
A CPM machine provides regular joint movements without people needing to use their muscles. It can help bend a joint that may be stiff and difficult to move.
A person can place the affected body part into the CPM machine and control the machine with a handheld control. For example, they can use the control to start and stop the motion, as well as adjust the levels of movement.
The amount of time a person needs to use a CPM machine for will depend on their condition and which joint they are using it on. A healthcare professional will offer instructions on how to use the machine and for how long.
For example, a person using a CPM machine for hip recovery may use it for 4 hours per day for a period of 4 weeks. Healthcare professionals may advise others to use the machine for 45 minutes at a time and rest between sessions.
A CPM machine may have benefits for the following joints:
Knee
Some people may use a CPM machine for recovery from knee replacement surgery.
One 2014 review looked at the effectiveness of using a CPM machine after undergoing knee replacement surgery. The review covered 24 studies involving 1,445 participants.
It found that people using a CPM machine experienced the following benefits:
- At week 6, participants using a CPM machine could bend their knee around 2 degrees more than those who did not use CPM.
- At week 6, participants using a CPM machine scored their pain at an average of 2.6 out of 10, compared with 3 out of 10 for those who did not use CPM.
- At month 6, people using CPM rated their quality of life one point higher than those not using a CPM machine.
- On average, people using CPM had a 15% risk of experiencing a medical problem, compared with 16.3% for people not using CPM.
- On average, people using CPM had a 1.6% risk of needing manipulation of the knee under anesthetics, compared with a 7.2% risk among people not using CPM.
However, the authors conclude that CPM did not provide any significant improvements in outcome for people who underwent knee replacement surgery.
Hip
Physical therapy through the use of a CPM machine may help aid recovery after undergoing hip surgery.
The aim of physical therapy is to:
- increase flexibility
- improve range of motion
- reduce inflammation
- relieve painful symptoms
- reduce the risk of stiffness and the development of scar tissue
Using a CPM machine may help reduce loss of motion, which a person would require extensive physical therapy to regain.
For the hip, a person may use a CPM machine for 4 hours per day for a period of 4 weeks.
A person can get a CPM machine to use at their home. They may be able to request a CPM machine through their hospital and have the machine arrive at the hospital on the day of their surgery.
If a person has access to Medicare health insurance, they may be eligible for a CPM machine to use at their home. If they meet the criteria and require a CPM machine after undergoing knee surgery, Medicare can provide a CPM machine for people to use at their home for up to 21 days.
People can discuss costs and whether they are able to rent or buy the machine with their doctor. It is also possible to purchase a CPM machine online or from companies selling medical equipment.
Learn more about Medicare coverage for physical therapy here.
Using a CPM machine may help increase range of motion after undergoing surgery on a joint. A person may use a CPM machine after undergoing surgery on the knee or hip.
So far, research is unclear as to whether or not a CPM machine provides any significant benefits for recovery after surgery.
The effects of a CPM machine may depend on the individual’s condition and the affected joint. In some cases, using a CPM machine may help improve range of motion and relieve pain.
People can discuss the potential benefits of using a CPM machine with their doctor.
If a person experiences any negative effects of using a CPM machine — such as increased pain, swelling, or numbness — they should stop using it and contact a doctor straight away.