Continuous passive motion following total knee arthroplasty in people with arthritis

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.