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PTA Blog Talk

Continuous Passive Motion

Published November 3, 2010 3:54 PM by Jason Marketti

In my search for information on total knee arthroplasty (TKA) procedures, I had come across several articles regarding the effectiveness of continuous passive motion (CPM). In my experience, CPM is great in the acute-care setting to initialize mobility but after several weeks of a great TKA program it becomes ineffective with increasing ROM. I have had patients with AROM of more than 100 degrees insist on using the CPM machine because, "The doctor ordered it." I gently tried to explain that keeping the CPM on would not enhance the ROM but the patient didn't seem to hear me. I thought if the patient was happy keeping her leg in the machine and it was not detrimental to her program, I wasn't going to argue with her.

I have also treated TKA patients taller than six feet and the CPM machines we had did not properly fit. I called in several therapists to assist me on this and no matter what we tried we were not able to align the knee correctly. The same thing happened when we treated little people. I guess the machines are one size fits most.

Explaining how to use the controls of the CPM machine becomes a double-edged sword with the patients too. The PT will usually set the machine up at evaluation and when I enter the room the next day the patient has successfully kept the CPM at 10 degrees of extension and 50 degrees of flexion. After I reset the ROM to the previous settings and explain that the CPM will help bend and straighten the knee, the patient will press the button and stop the machine with the slightest amount of pain. Often I will have to check back several times throughout the day to ensure the patient has kept the corrected ROM.

Then there was the patient with 60 degrees of flexion and 20 degrees of extension (this was PROM). She hated the machine because it caused her pain and she never used it. Our TKA exercises created pain for her and she stopped coming to therapy. Even gentle stretching caused her pain so she insisted on going home. All of the patient education could not have made this patient stay in the SNF. She told me on the day of discharge that her arthritis caused her so much pain and after the surgery she did not ever want to feel that pain again. "I would rather walk with a limp than go through the pain of therapy."


Good point Dean.  Pain medication is an important aspect of treating someone with a joint replacement, especially a knee.  I try to coordinate therapy and nsg to ensure the patient will have reduced discomfort during therapy.

Jason Marketti November 4, 2010 11:47 PM

Jason, I understand completely your frustration with CPM compliance and lack of precision. I guess some things haven't changed in the 15 years since I've had cause to use one.

The thing that sticks with me is that you haven't mentioned pain relief for your patients. Can we assume that they were given appropriate pain medication at the appropriate times? I have seen therapists start working on a patient's knee when they hadn't received the medication timely.

Just a thought, Dean

Dean Metz November 3, 2010 1:33 PM

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About this Blog

    Jason J. Marketti
    Occupation: Physical Therapist Assistant
    Setting: San Jacinto, CA
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