[Effectiveness of continuous passive motion after total knee replacement]

Continuous passive motion (CPM) is frequently used method in the early post-operative rehabilitation in patients after knee surgery. Aim of this study was to evaluate the effectiveness of CPM after primary total knee arthroplasty. Efficacy was assesed in terms of clinical score and functional recovery. 93 patients (101 knee joints) undergoing total knee replacement were assigned into two groups. The experimental group received continuous passive motion and active exercises. A control group received conventional physical therapy only. CPM was initiated in the first day after surgery, for 120 minutes, starting with 0-40 degrees range of motion, increased as tolerated (mean 10 degrees per day) and maintained during the hospital stay. Outcome measures were those included in Knee Society Score (KSS). Functional recovery was evaluated using WOMAC. All subjects were evaluated once before the surgery and on 10th day postoperatively. Mean clinical score (KSS) at the day 10 was 70 +/- 15 points in the experimental group and 74 +/- 12 in a control group. There were no statistical difference between the two groups for any outcome measures. CPM group mean range of motion was 83 degrees +/- 14 degrees and a group without CPM 77 degrees +/- 21 degrees. KSS functional score was 66 +/- 9 points in the experimental group compared to 62 +/- 7 points in a control group. Subjective estimation of pain level, joint stiffness and function showed no statistical difference between the two groups regarding total and subscale scores. Mean total score was 24 +/- 19 points in the CPM group and 22 +/- 17 in a group without CPM. These findings show that CPM had no significant advantage in terms of improving clinical measurements. However, there was beneficial effect on subjective assessment of pain level, joint stiffness and functional ability.