Randomized Controlled Trial of the Effectiveness of Continuous Passive Motion After Total Knee Replacement

To determine the effects of using a continuous passive motion (CPM) device for individuals with poor range of motion (ROM) after a total knee replacement (TKR) admitted for postacute rehabilitation.Randomized controlled trial.Inpatient rehabilitation facility (IRF).Adults (N=141) after TKR with initial active knee flexion <75° on admission to the IRF.Two randomized groups: group 1 (n=71) received the conventional 3 hours of therapy per day, and group 2 (n=70) received the addition of daily CPM use for 2 hours throughout their length of stay.The primary outcome measure was active knee flexion ROM. Secondary outcome measures included active knee extension ROM length of stay, estimate of function using the FIM and Timed Up and Go test, girth measurement, and self-reported Western Ontario and McMaster Universities Osteoarthritis Index scores.All subjects significantly improved from admission to discharge in all outcome measures. However, there were no statistically significant differences in any of the discharge outcome measures of the CPM group compared with the non-CPM group.CPM does not provide an additional benefit over the conventional interventions used in an IRF for patient after TKR, specifically in patients with poor initial knee flexion ROM after surgery.