Effect of continuous passive motion on the early recovery outcomes after total knee arthroplasty

Introduction Continuous passive motion (CPM) is a frequently used method in the early post-operative rehabilitation of patients after knee surgery. In this study, the effectiveness of the CPM method was evaluated after primary total knee arthroplasty during an early recovery period. Methods Eighty patients undergoing total knee arthroplasty were assigned into two groups. The experimental group received CPM and active exercises, while the control group active exercises only. All subjects were evaluated once before the surgery and at a discharge, in terms of mean active range of motion (AROM), mean Knee Society Score (KSS), and Western Ontario and MacMaster Universities Osteoarthritis Index (WOMAC). Results The mean AROM for the experimental group was 82.3 degrees +/- 14.3 degrees and 76.1 degrees +/- 22.2 degrees for the control. The mean KSS score was 136.4 +/- 19.3 points for the experimental group, and 135.7 +/- 15.1 for the control. There were no statistical differences between the two groups. The KSS functional score was 66.4 +/- 8.1 points for the experimental group compared to 62.2 +/- 7.3 points for the control, but there was a statistically significant difference between the groups at discharge from the hospital (p = 0.009). A subjective estimation of the pain level, joint stiffness and function also showed a statistically significant difference between the two groups (38.6 +/- 14.3 points for the CPM group and 21.2 +/- 15.7 for the control). Conclusion These findings show that there is no significant effect of CPM in terms of improving clinical measurements. However, there was a significant beneficial effect on the subjective assessment of pain level, joint stiffness, and functional ability.