Table of ContentsView AllTable of ContentsBenefitsLimitationsWhen It’s UsedInstructionsOther UsesFrequently Asked Questions
Table of ContentsView All
View All
Table of Contents
Benefits
Limitations
When It’s Used
Instructions
Other Uses
Frequently Asked Questions
Acontinuous passive motion(CPM) machine is a motorized device that gently moves a joint through a set range of motion. It is sometimes used after knee replacement surgery to prevent scar tissue development, reduce stiffness, and restore normal function.
In theory, placing the knee in this device soon after surgery does just that.But although there is some benefit to using CPM in the first days and weeks of recovery, there is no difference in the overall outcomes of those who use CPM vs. those who don’t.
This article delves into why CPM may be recommended after knee replacement surgery (and why it may not). It reviews the pros and cons of using a CPM machine, how to use one, and other surgeries for which CPM may be a part of the recovery period.
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Benefits of CPM
A 2022 study found that total knee replacement patients who received CPM and did active exercises reported more improvement in subjective measures of pain, stiffness, and function than people who only did active exercises. However, there was no significant difference in objective measures such as range of motion.
Some healthcare providers also argue that patients do have an initial increase in motion following surgery that is more rapid than patients who do not use a CPM.
Additionally, there are some specific procedures, such as a release of contracture or adhesions, where a CPM can be an important part of the recovery from knee surgery.
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Limitations of CPM
While there may be a psychological benefit for the patient in doing something active to help their recovery, studies have shown no evidence that CPM makes any substantial difference in the long run after knee replacement surgery. Studies have shown that within four to six weeks of knee replacement surgery, patients who use CPM and those who don’t have about the same range of knee motion.
ProsFaster initial increase in motionPsychological benefit of an action being takenConsMakes no difference in recovery and range of motion in long termKeeps patient in bed rather than doing active therapy
ProsFaster initial increase in motionPsychological benefit of an action being taken
Faster initial increase in motion
Psychological benefit of an action being taken
ConsMakes no difference in recovery and range of motion in long termKeeps patient in bed rather than doing active therapy
Makes no difference in recovery and range of motion in long term
Keeps patient in bed rather than doing active therapy
When CPM Is Used
For many years, CPM machines were seen as a significant medical advancement that could help prevent postoperative complications from joint surgery. They were used routinely after a number of different surgical procedures, particularly knee replacement.
And the need is there: While at least 80% of people are satisfied with the results of knee replacement,stiffness of the joint remains a persistent problem. This can be a serious complication and is one of the more common reasons why people are dissatisfied with knee replacement surgery.
The machines are no longer widely used because of the multiple studies that found CPM following knee replacement surgery has minimal benefits.
However, some surgeons still recommend CPM following knee surgery when the limited pros outweigh the cons in a particular case.
Stiffness After Knee Replacement
1:33Click Play to Learn About CPM Therapies
1:33
Click Play to Learn About CPM Therapies
How to Use a CPM Machine
CPM machines are usually controlled with a remote control that starts and stops the machine and lets you adjust the speed and the amount of flex.
How Long Should You Use a CPM Machine?You should use a CPM machine only for as long as your healthcare provider recommends. This is usually around four hours a day for three to four weeks after surgery, but it will depend on what procedure you had done.
How Long Should You Use a CPM Machine?
You should use a CPM machine only for as long as your healthcare provider recommends. This is usually around four hours a day for three to four weeks after surgery, but it will depend on what procedure you had done.
Other CPM Uses
CPM is most commonly used after knee replacement surgery, but it can also be used after other joint surgeries, such as:
CPM has also been used to help treat lower back pain. Research into this use is limited, but one small study found that people who used the machine for 10 minutes one to three times a day for three weeks had less pain.
CPM machines are not effective for every type of joint surgery. Furthermore, some healthcare providers no longer recommend them and will suggest alternative therapies instead, such as physical therapy. You should use CPM only if your healthcare provider recommends it.
12 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Trochimczuk R, Kuźmierowski T, Anchimiuk P.Study of CPM device used for rehabilitation and effective pain management following knee alloplasty.Int J Appl Mech Eng. 2017;22(1):241-251. doi:10.1515/ijame-2017-0014Harvey LA, Brosseau L, Herbert RD.Continuous passive motion following total knee arthroplasty in people with arthritis.Cochrane Database Syst Rev. 2014;(2):CD004260. doi:10.1002/14651858.CD004260.pub3Richter M, Trzeciak T, Kaczmarek M.Effect of continuous passive motion on the early recovery outcomes after total knee arthroplasty.Int Orthop. 2022;46(3):549-53. doi:10.1007/s00264-021-05245-5Fan XY, Ma JH, Wu X, et al.How much improvement can satisfy patients? Exploring patients' satisfaction 3 years after total knee arthroplasty.J Orthop Surg Res. 2021;16(1):389. doi:10.1186/s13018-021-02514-2Rex C.Continuous passive motion therapy after total knee arthroplasty.Nursing.2018;48(5):55-57. doi:10.1097/01.NURSE.0000531010.25095.80Cunningham DJ, Lewis BD, Hutyra CA, Mather RC, Olson SA.Early recovery after hip arthroscopy for femoroacetabular impingement syndrome: a prospective, observational study.J Hip Preserv Surg. 2017;4(4):299-307. doi:10.1093/jhps/hnx026Munsch M, Vajapey SP, Vasileff WK, Ellis T, DeWitt J, Ryan J.Use of continuous passive motion device after arthroscopic hip surgery decreases post-operative pain: a randomized controlled trial.J Clin Orthop Trauma. 2021;23:101646. doi:10.1016/j.jcot.2021.101646Viveen J, Doornberg JN, Kodde IF, et al.Continuous passive motion and physical therapy (CPM) versus physical therapy (PT) versus delayed physical therapy (DPT) after surgical release for elbow contractures; a study protocol for a prospective randomized controlled trial.BMC Musculoskelet Disord. 2017;18(1):484. doi:10.1186/s12891-017-1854-0Schulze C, Knaack F, Goosmann M, Mittelmeier W, Bader R.Continuous passive motion in orthopaedic rehabilitation of the shoulder girdle - a literature survey.Rehabilitation (Stuttg). 2021;60(6):364-373. doi:10.1055/a-1500-8567Shirzadi A, Farzad M, Farhoud AR, Shafiee E.Application of continuous passive motion in patients with distal radius fractures: a randomized clinical trial.Hand Surg Rehabil. 2020;39(6):522-527. doi:10.1016/j.hansur.2020.08.001Gavish L, Barzilay Y, Koren C, Stern A, Weinrauch L, Friedman DJ.Novel continuous passive motion device for self-treatment of chronic lower back pain: a randomised controlled study.Physiotherapy. 2015;101(1):75-81. doi:10.1016/j.physio.2014.06.003Centers for Medicare and Medicaid Services.Continuous passive motion (CPM) machines.Additional ReadingMistry JB, Elmallah RD, Bhave A, et al.Rehabilitative guidelines after total knee arthroplasty: A review.J Knee Surg.2016;29(3):201-17. doi:10.1055/s-0036-1579670
12 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Trochimczuk R, Kuźmierowski T, Anchimiuk P.Study of CPM device used for rehabilitation and effective pain management following knee alloplasty.Int J Appl Mech Eng. 2017;22(1):241-251. doi:10.1515/ijame-2017-0014Harvey LA, Brosseau L, Herbert RD.Continuous passive motion following total knee arthroplasty in people with arthritis.Cochrane Database Syst Rev. 2014;(2):CD004260. doi:10.1002/14651858.CD004260.pub3Richter M, Trzeciak T, Kaczmarek M.Effect of continuous passive motion on the early recovery outcomes after total knee arthroplasty.Int Orthop. 2022;46(3):549-53. doi:10.1007/s00264-021-05245-5Fan XY, Ma JH, Wu X, et al.How much improvement can satisfy patients? Exploring patients' satisfaction 3 years after total knee arthroplasty.J Orthop Surg Res. 2021;16(1):389. doi:10.1186/s13018-021-02514-2Rex C.Continuous passive motion therapy after total knee arthroplasty.Nursing.2018;48(5):55-57. doi:10.1097/01.NURSE.0000531010.25095.80Cunningham DJ, Lewis BD, Hutyra CA, Mather RC, Olson SA.Early recovery after hip arthroscopy for femoroacetabular impingement syndrome: a prospective, observational study.J Hip Preserv Surg. 2017;4(4):299-307. doi:10.1093/jhps/hnx026Munsch M, Vajapey SP, Vasileff WK, Ellis T, DeWitt J, Ryan J.Use of continuous passive motion device after arthroscopic hip surgery decreases post-operative pain: a randomized controlled trial.J Clin Orthop Trauma. 2021;23:101646. doi:10.1016/j.jcot.2021.101646Viveen J, Doornberg JN, Kodde IF, et al.Continuous passive motion and physical therapy (CPM) versus physical therapy (PT) versus delayed physical therapy (DPT) after surgical release for elbow contractures; a study protocol for a prospective randomized controlled trial.BMC Musculoskelet Disord. 2017;18(1):484. doi:10.1186/s12891-017-1854-0Schulze C, Knaack F, Goosmann M, Mittelmeier W, Bader R.Continuous passive motion in orthopaedic rehabilitation of the shoulder girdle - a literature survey.Rehabilitation (Stuttg). 2021;60(6):364-373. doi:10.1055/a-1500-8567Shirzadi A, Farzad M, Farhoud AR, Shafiee E.Application of continuous passive motion in patients with distal radius fractures: a randomized clinical trial.Hand Surg Rehabil. 2020;39(6):522-527. doi:10.1016/j.hansur.2020.08.001Gavish L, Barzilay Y, Koren C, Stern A, Weinrauch L, Friedman DJ.Novel continuous passive motion device for self-treatment of chronic lower back pain: a randomised controlled study.Physiotherapy. 2015;101(1):75-81. doi:10.1016/j.physio.2014.06.003Centers for Medicare and Medicaid Services.Continuous passive motion (CPM) machines.Additional ReadingMistry JB, Elmallah RD, Bhave A, et al.Rehabilitative guidelines after total knee arthroplasty: A review.J Knee Surg.2016;29(3):201-17. doi:10.1055/s-0036-1579670
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Trochimczuk R, Kuźmierowski T, Anchimiuk P.Study of CPM device used for rehabilitation and effective pain management following knee alloplasty.Int J Appl Mech Eng. 2017;22(1):241-251. doi:10.1515/ijame-2017-0014Harvey LA, Brosseau L, Herbert RD.Continuous passive motion following total knee arthroplasty in people with arthritis.Cochrane Database Syst Rev. 2014;(2):CD004260. doi:10.1002/14651858.CD004260.pub3Richter M, Trzeciak T, Kaczmarek M.Effect of continuous passive motion on the early recovery outcomes after total knee arthroplasty.Int Orthop. 2022;46(3):549-53. doi:10.1007/s00264-021-05245-5Fan XY, Ma JH, Wu X, et al.How much improvement can satisfy patients? Exploring patients' satisfaction 3 years after total knee arthroplasty.J Orthop Surg Res. 2021;16(1):389. doi:10.1186/s13018-021-02514-2Rex C.Continuous passive motion therapy after total knee arthroplasty.Nursing.2018;48(5):55-57. doi:10.1097/01.NURSE.0000531010.25095.80Cunningham DJ, Lewis BD, Hutyra CA, Mather RC, Olson SA.Early recovery after hip arthroscopy for femoroacetabular impingement syndrome: a prospective, observational study.J Hip Preserv Surg. 2017;4(4):299-307. doi:10.1093/jhps/hnx026Munsch M, Vajapey SP, Vasileff WK, Ellis T, DeWitt J, Ryan J.Use of continuous passive motion device after arthroscopic hip surgery decreases post-operative pain: a randomized controlled trial.J Clin Orthop Trauma. 2021;23:101646. doi:10.1016/j.jcot.2021.101646Viveen J, Doornberg JN, Kodde IF, et al.Continuous passive motion and physical therapy (CPM) versus physical therapy (PT) versus delayed physical therapy (DPT) after surgical release for elbow contractures; a study protocol for a prospective randomized controlled trial.BMC Musculoskelet Disord. 2017;18(1):484. doi:10.1186/s12891-017-1854-0Schulze C, Knaack F, Goosmann M, Mittelmeier W, Bader R.Continuous passive motion in orthopaedic rehabilitation of the shoulder girdle - a literature survey.Rehabilitation (Stuttg). 2021;60(6):364-373. doi:10.1055/a-1500-8567Shirzadi A, Farzad M, Farhoud AR, Shafiee E.Application of continuous passive motion in patients with distal radius fractures: a randomized clinical trial.Hand Surg Rehabil. 2020;39(6):522-527. doi:10.1016/j.hansur.2020.08.001Gavish L, Barzilay Y, Koren C, Stern A, Weinrauch L, Friedman DJ.Novel continuous passive motion device for self-treatment of chronic lower back pain: a randomised controlled study.Physiotherapy. 2015;101(1):75-81. doi:10.1016/j.physio.2014.06.003Centers for Medicare and Medicaid Services.Continuous passive motion (CPM) machines.
Trochimczuk R, Kuźmierowski T, Anchimiuk P.Study of CPM device used for rehabilitation and effective pain management following knee alloplasty.Int J Appl Mech Eng. 2017;22(1):241-251. doi:10.1515/ijame-2017-0014
Harvey LA, Brosseau L, Herbert RD.Continuous passive motion following total knee arthroplasty in people with arthritis.Cochrane Database Syst Rev. 2014;(2):CD004260. doi:10.1002/14651858.CD004260.pub3
Richter M, Trzeciak T, Kaczmarek M.Effect of continuous passive motion on the early recovery outcomes after total knee arthroplasty.Int Orthop. 2022;46(3):549-53. doi:10.1007/s00264-021-05245-5
Fan XY, Ma JH, Wu X, et al.How much improvement can satisfy patients? Exploring patients' satisfaction 3 years after total knee arthroplasty.J Orthop Surg Res. 2021;16(1):389. doi:10.1186/s13018-021-02514-2
Rex C.Continuous passive motion therapy after total knee arthroplasty.Nursing.2018;48(5):55-57. doi:10.1097/01.NURSE.0000531010.25095.80
Cunningham DJ, Lewis BD, Hutyra CA, Mather RC, Olson SA.Early recovery after hip arthroscopy for femoroacetabular impingement syndrome: a prospective, observational study.J Hip Preserv Surg. 2017;4(4):299-307. doi:10.1093/jhps/hnx026
Munsch M, Vajapey SP, Vasileff WK, Ellis T, DeWitt J, Ryan J.Use of continuous passive motion device after arthroscopic hip surgery decreases post-operative pain: a randomized controlled trial.J Clin Orthop Trauma. 2021;23:101646. doi:10.1016/j.jcot.2021.101646
Viveen J, Doornberg JN, Kodde IF, et al.Continuous passive motion and physical therapy (CPM) versus physical therapy (PT) versus delayed physical therapy (DPT) after surgical release for elbow contractures; a study protocol for a prospective randomized controlled trial.BMC Musculoskelet Disord. 2017;18(1):484. doi:10.1186/s12891-017-1854-0
Schulze C, Knaack F, Goosmann M, Mittelmeier W, Bader R.Continuous passive motion in orthopaedic rehabilitation of the shoulder girdle - a literature survey.Rehabilitation (Stuttg). 2021;60(6):364-373. doi:10.1055/a-1500-8567
Shirzadi A, Farzad M, Farhoud AR, Shafiee E.Application of continuous passive motion in patients with distal radius fractures: a randomized clinical trial.Hand Surg Rehabil. 2020;39(6):522-527. doi:10.1016/j.hansur.2020.08.001
Gavish L, Barzilay Y, Koren C, Stern A, Weinrauch L, Friedman DJ.Novel continuous passive motion device for self-treatment of chronic lower back pain: a randomised controlled study.Physiotherapy. 2015;101(1):75-81. doi:10.1016/j.physio.2014.06.003
Centers for Medicare and Medicaid Services.Continuous passive motion (CPM) machines.
Mistry JB, Elmallah RD, Bhave A, et al.Rehabilitative guidelines after total knee arthroplasty: A review.J Knee Surg.2016;29(3):201-17. doi:10.1055/s-0036-1579670
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