A Wireless Body Sensor Network for Clinical Assessment of the Flexion-Relaxation Phenomenon

Michele Paoletti,Paola Pierleoni,Massimo Vallasciani,Alberto Belli,Lorenzo Palma

doi:10.3390/electronics9061044

Michele Paoletti, Paola Pierleoni + Show 3 more

Open Access

https://doi.org/10.3390/electronics9061044

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Journal: Electronics	Publication Date: Jun 24, 2020
Citations: 6	License type: CC BY 4.0

Affiliation: Marche Polytechnic University

Abstract

An accurate clinical assessment of the flexion-relaxation phenomenon on back muscles requires objective tools for the analysis of surface electromyography signals correlated with the real movement performed by the subject during the flexion-relaxation test. This paper deepens the evaluation of the flexion-relaxation phenomenon using a wireless body sensor network consisting of sEMG sensors in association with a wearable device that integrates accelerometer, gyroscope, and magnetometer. The raw data collected from the sensors during the flexion relaxation test are processed by an algorithm able to identify the phases of which the test is composed, provide an evaluation of the myoelectric activity and automatically detect the phenomenon presence/absence. The developed algorithm was used to process the data collected in an acquisition campaign conducted to evaluate the flexion-relaxation phenomenon on back muscles of subjects with and without Low Back Pain. The results have shown that the proposed method is significant for myoelectric silence detection and for clinical assessment of electromyography activity patterns.

Highlights

The Flexion-Relaxation Phenomenon (FRP) term was adopted in 1955 by Floyd and Silver analysing the erector spinae muscles [1]
In order to overcome these limitations in this paper we propose an flexion-relaxation ratio (FRR) method that uses a nominal threshold reference value to detect the presence or absence of FRP; this cutoff is an empirical value obtained during the analysis of the data collected in the acquisition campaign [43]
This paper deepens the investigation of FRP on back muscles using a Wireless Body Sensor Network (WBSN) composed of four surface electromyography (sEMG) sensors and a wearable device that integrates accelerometer, gyroscope, and magnetometer

Summary

Introduction

The Flexion-Relaxation Phenomenon (FRP) term was adopted in 1955 by Floyd and Silver analysing the erector spinae muscles [1]. It consists of a back muscle electrical activity silence which typically occurs during the trunk full flexion. This effect is believed to be the result of ligaments activity and other passive elements of the spine that absorb the load of muscles. Floyd and Silver observed that myoelectric quiescence was caused by a reflex due to stretching in which the load torque of the upper body was transferred from the active to the passive spinal elements. It is known that the pain interferes with both afferent and efferent aspects of neuromuscular control [4,5,6]

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