Dynamic surface electromyography topography: a new assessment tool for low back pain rehabilitation

Abstract

INTRODUCTION: The dynamic surface electromyography (SEMG) topography can visualize muscle activity during dynamic motion, to be an objective approach to evaluate the progress of low back pain (LBP) rehabilitation. This study was aimed to quantity the pattern features of dynamic SEMG topography from in-vivo lumbar flexion-extension test during LBP rehabilitation, and to propose the potential use of this technique in LBP rehabilitation assessment. METHODS: EMG signals were recorded in 41 non-specific LBP patients during lumbar flexion-extension. Root-mean-square (RMS) was calculated, while the topographies of RMS distribution were constructed by cubic spline interpolation. The highest 20% RMS value region of the topography was defined as high activity. The relative area (RA), width (RW) and width/height ratio (WHR) of high activity were calculated. All 41 patients received a 12 weeks intensive rehabilitation program, while visual analogy pain-rating scale (VAS) and the Oswestry Disability Questionnaire (ODQ) were evaluated before and after rehabilitation. The progress of rehabilitation was classified as good and fair based on the minimal clinically important difference (MCID). Changes in SEMG topography between rehabilitation were compared in good and fair progression groups with one way ANOVA. RESULTS: Comparing with reported normal SEMG topography, LBP patients had a different dynamic SEMG topography, with an asymmetric, broad, or disorganized distribution. SEMG topography in LBP with good progression showed significant increased RA and RW as well as a significant decreased WHR (p<0.05 by ANOVA). DISCUSSION: The alternation of SEMG topography in the LBP patients would be an indication of good progression of LBP rehabilitation. SEMG topography provides a quantitative and objective assessment for LBP rehabilitation. It may help identify subjects who will respond to exercise based care, which can benefit the decision making of LBP management strategy.