Question: Is continuous passive motion (CPM) effective after total knee arthroplasty (TKA)?

Data sources: Studies were identified by searching (to December 2003) MEDLINE, EMBASE/Excerpta Medica, HealthSTAR, Sports Discus, CINAHL, the Cochrane Controlled Trials Register, PEDro, and the specialized register of the Cochrane Collaboration Musculoskeletal Review Group; scanning the reference lists of included trials; and contacting experts in the field.

Study selection and assessment: Studies in English or French were selected if they were randomized controlled trials (RCTs), controlled clinical trials, case-control studies, or cohort studies comparing CPM with placebo, no treatment, or active interventions in patients who were ≥18 years of age and who underwent total knee arthroplasty for degenerative joint disease. The quality of each study was assessed with use of the 5-point Jadad scale (higher scores = better quality).

Main outcome measures: Active and passive knee range of motion (ROM), length of hospital stay, pain, and quadriceps strength.

Main results: 14 studies met the inclusion criteria (n = 952); 10 studies were RCTs. Quality scores ranged from 1 to 3. Pooled analysis was done for CPM plus physiotherapy (PT) compared with PT alone. CPM plus PT improved active knee flexion and shortened hospital length of stay more than PT alone, but the groups did not differ for other range-of-motion outcomes (Table). Two RCTs showed no difference between groups for pain at 1 and 2 weeks, respectively. One RCT showed no difference in quadriceps strength (weighted mean difference [WMD], 1.60; 95% confidence interval, -1.88 to 5.08). One RCT, comparing CPM plus PT vs splinting plus PT, showed that CPM improved knee flexion at up to 1 year of follow-up (WMD, 9.00°; CI, 7.63 to 10.37). No differences were seen for main outcomes in studies comparing short-term and long-term CPM (1 RCT), small-range vs big-range CPM (1 RCT), or low-range vs high-range CPM (1 RCT).

Conclusions: In patients who have had total knee arthroplasty, CPM plus PT increases active knee flexion more than PT alone 2 weeks after surgery and reduces hospital length of stay. Other range-of-motion outcomes are not significantly different between CPM and PT. Outcomes are also not different when comparing CPM with splinting (except for knee flexion) or comparing different CPM applications.