The effect of continuous passive motion and sling exercise training on clinical and functional outcomes following total knee arthroplasty: a randomized active-controlled clinical study

Abstract

Background: The parallel-group randomized active-controlled clinical study was conducted to compare the effectiveness of two in-hospital range of motion (ROM) exercise programs following total knee arthroplasty (TKA). Continuous passive motion (CPM) is frequently used to increase ROM and improve postoperative recovery despite little conclusive scientific evidence. In contrast, a new active sling-based ROM therapy requires the activation of the knee joint muscles and dynamic joint stabilization. It was hypothesized that higher demands on muscle strength and muscle coordination during sling exercise training (ST) might be advantageous for early recovery following TKA.

Methods: A total of 125 patients undergoing primary TKA were assessed for eligibility. Thirty-eight patients were randomly assigned to receive ST or CPM (control intervention) during hospital stay. Patients were assessed before TKA for baseline measurement (pretest), 1 day before discharge (posttest) and 3 months after TKA (follow-up). The passive knee flexion range of motion (pFL) was the primary outcome measure. Secondary outcome measures included active knee flexion range of motion, active and passive knee extension ROM, static postural control, physical activity, pain, length of hospital stay as well as clinical, functional and quality-of-life outcomes (SF-36, HSS and WOMAC scores). Data were analyzed according to the intention-to-treat principle. Differences between the groups were tested for significance by the unpaired Student's t test or an analysis of covariance (ANCOVA) adjusted for baseline, weight, sex, age, pain and physical activity.

Results: A between-group difference could be determined at posttest. The pFL was significantly higher by 6.0° (95% CI 0.9 to 11.2°; P = 0.022) in the ST group. No difference between groups in pFL was documented at follow-up. Furthermore, no significant differences could be observed for any secondary outcome measure at posttest and follow-up.

Conclusions: ST seems to have a clinically relevant beneficial short-term effect on pFL compared to CPM. The results support the implementation of ST in rehabilitation programs following TKA.

Level of evidence: Therapy, level 2b.

Figure 1

Sling exercise training.

Figure 2

CONSORT flow diagram to show the flow of participants through the trial [34].

Figure 3

The Graphs show the comparisons between the groups. A. Passive knee flexion range of motion (ROM). B. Active knee flexion ROM. The dark grey line represents the sling exercise training group (ST) and the light grey line the continuous passive motion group (CPM). Data are presented as estimated marginal means and standard deviation (ANCOVA: posttest adjusted for baseline, sex, weight, age, pain and physical activity; follow-up adjusted for baseline, sex, weight, age and physical activity. * denotes a significant difference (P ≤ 0.025).