Effectiveness of surface electromyographic biofeedback-triggered neuromuscular electrical stimulation on knee rehabilitation

Purpose. The purpose of this single-blinded, randomized study was to investigate the effectiveness of surface electromyographic biofeedback-triggered neuromuscular electrical stimulation (sEMG-triggered NMES) in post-surgical knee patients. Methods. Twenty-five participants were randomly assigned to one of the two groups: (1) sEMG-triggered NMES intervention with exercise group, or (2) exercise-only comparison group. All participants received outpatient physical therapy treatment 2 to 3 times a week for 12 visits. Knee extension active range of motion (AROM) using a universal goniometer, pain intensity using a visual analog scale (VAS), and function using the Lower Extremity Functional Scale (LEFS) were collected at the first, sixth, and twelfth visits. Peak isometric extensor torque at 60° knee flexion was assessed using an electromechanical dynamometer at three months post surgery. Data analysis. Three 2 x 3 (group by visit) ANOVA's with repeated measures on the visit factor were used to compare knee AROM (degrees), VAS (cm), and LEFS (% score). A paired samples t-test was used to evaluate the peak torque (Nm) differences between involved and uninvolved extremity. An independent samples t-test was used to analyze the peak torque index (%) of the involved extremity compared to the uninvolved extremity. Results . No significant difference was found between groups for AROM, VAS, and LEFS. Significance was found across each visit factor for AROM, VAS, and LEFS (p < 0.01). The peak torque of the involved extremity had significantly less torque than the uninvolved extremity (p < 0.01). No significant difference was found for the peak torque index between groups. Conclusions. The results of this study do not support the use of sEMG-triggered NMES as an adjunct to exercise in rehabilitation following knee surgery. The greatest improvements for AROM, pain, and function were seen from visit 1 to 6 suggesting exercise soon after surgery is beneficial. A strength deficit is still present at 12 weeks postoperatively. The results of this study support physical therapy exercise intervention in the first 12 weeks after knee surgery and suggest further exercise prescription is needed.