Continuous passive motion after knee replacement surgery

Harvey LA, Brosseau L, Herbert RD

Published Online:

March 17, 2010

This summary of a Cochrane review presents what we know about the effect of continuous passive motion (CPM) as a treatment to improve range of motion and function after knee replacement surgery.

In people who had knee replacement surgery:

- Continuous passive motion improved their range of motion slightly;

- Continuous passive motion may not make any difference to how long they stayed in hospital;

We often do not have precise information about side effects and complications. This is particularly true for rare but serious complications.

What is osteoarthritis and what is continuous passive motion (CPM)?

Osteoarthritis of the knee can make the knee joint painful and unstable. Knee replacement surgery is a treatment that can sometimes help this condition. One side effect of having knee surgery is stiffness in the knee. When your knees are stiff, it can be difficult to stand from a sitting position. Up to a year later, some people walk and climb stairs more slowly than they did before surgery.

This has led to the development of a therapy called continuous passive motion (CPM). Continuous passive motion is a way of providing regular movement to your knee using a machine. The movement is passive which means that machine moves your knee for you through a preset range of motion. The movement that tests the range of motion for your knee is called flexion. Flexion is a movement which moves the two ends of a jointed body part closer to each other. In this case, knee flexion is how close you are able to move the heel of your foot close to your buttocks. This distance is measured in degrees.

Best estimate of what happens to people who have CPM after knee replacement surgery:

Range of motion - Active knee flexion

- People who did not have CPM were able to move their knee an average of 75 degrees

- People who did have CPM were able to move their knee 3 degrees more, an average of 78 degrees.

Range of motion - Passive knee Flexion

- People who did not have CPM were able to move their knee an average of 82 degrees

- People who did have CPM were able to move their knee 2 degrees more, an average of 84 degrees.

Length of Hospital Stay

- People who did not have CPM stayed in hospital an average of 13 days, about the same as people who did have CPM.

Function

- We could not obtain an accurate pooled estimate of the changes to physical function in this review.

Abstract (click to read)

Background:

Total knee arthroplasty is a common intervention for patients with arthritis. Post-surgical rehabilitation often includes continuous passive motion. However, it is not clear whether continuous passive motion is effective.

Objectives:

To evaluate the effectiveness of continuous passive motion following total knee arthroplasty in people with arthritis.

Search strategy:

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2009, Issue 3), MEDLINE (January 1966 to January 2009), EMBASE (January 1980 to January 2009), CINAHL (January 1982 to January 2009), AMED (January 1985 to January 2009) and PEDro (to January 2009).

Selection criteria:

Randomised controlled trials in which the experimental group received continuous passive motion, and both the experimental and control groups received similar postoperative care and therapy following total knee arthoplasty in people with arthritis.

Data collection and analysis:

Two reviewers independently selected trials for inclusion. Data were then extracted and the quality of trials assessed. The primary outcomes were active knee flexion range of motion, passive knee flexion range of motion, active knee extension range of motion, passive knee extension range of motion, length of hospital stay, function and incidence of manipulation under anaesthesia. The secondary outcomes were pain, swelling and quadriceps strength. Effects were estimated as weighted mean differences or standardised mean differences with 95% confidence intervals (CI). Meta-analyses were performed using random-effects models for continuous variables.

Main results:

Twenty randomised controlled trials of 1335 participants met the inclusion criteria. There is high-quality evidence that continuous passive motion increases passive knee flexion range of motion (mean difference 2 degrees, 95% CI 0 to 5) and active knee flexion range of motion (mean difference 3 degrees, 95% CI 0 to 6). These effects are too small to be clinically worthwhile. There is low-quality evidence that continuous passive motion has no effect on length of hospital stay (mean difference -0.3 days; 95% CI -0.9 to 0.2) but reduces the need for manipulation under anaesthesia (relative risk 0.15; 95% CI 0.03 to 0.70).

Authors' conclusions:

The effects of continuous passive motion on knee range of motion are too small to justify its use. There is weak evidence that continuous passive motion reduces the subsequent need for manipulation under anaesthesia.

This record should be cited as:

Harvey LA, Brosseau L, Herbert RD. Continuous passive motion following total knee arthroplasty in people with arthritis. Cochrane Database of Systematic Reviews 2010, Issue 3. Art. No.: CD004260. DOI: 10.1002/14651858.CD004260.pub2

Assessed as up to date:

February 17, 2010

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Primary Review Group:

Musculoskeletal Group

Arthritis topics:

Osteoarthritis > Exercise and Rehabilitation

Health topics:

Rheumatology > Osteoarthritis > Rehabilitation

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Independent high-quality evidence for health care decision making

Continuous passive motion after knee replacement surgery

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