The aim of this study was to determine the effects of using a Continuous Passive Motion (CPM) device for people with poor range of motion after a total knee replacement (TKR) admitted for post acute rehabilitation. A randomized controlled trial consisting of adults (n=141) following TKR with initial active knee flexion of less than 75 degrees upon admission to the inpatient rehabilitation facility (IRF). Two randomized groups: group 1 (n=71) patients received the conventional 3 hours of therapy per day and group 2 (n=70) were given an addition of daily CPM use for 2 hours throughout their length of stay. The primary outcome measure was active knee flexion range of motion (ROM). Secondary outcome measures consisted of: active knee extension ROM; an estimate of function using the Functional Independence Measure (FIM); and Timed Up and Go Test (TUG); girth measurement; and, self- reported Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). All of the patients 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 in comparison to the non-CPM group.
The study found that CPM does not provide an additional benefit over the conventional interventions used in an inpatient rehabilitation facility for individuals following TKR, particularly in patients with poor initial knee flexion ROM after surgery.