Measuring lumbar back motion during functional activities using a portable strain gauge sensor-based system: a comparative evaluation and reliability study

TL;DR

This study evaluates the accuracy and reliability of the portable Epionics SPINE system for measuring lumbar back motion during various functional activities, comparing it to a Vicon system in healthy participants.

Contribution

It provides a comparative analysis of a portable sensor system against a gold-standard motion capture system, establishing its validity and reliability for clinical and research use.

Findings

High agreement between systems for chair rising, box lifting, and CMJ.

Moderate to high reliability for most parameters, except running ROM.

Systematic underestimation of lumbar angles during walking and running.

Abstract

Quantifying lumbar back motion during functional activities in real-life environments may contribute to a better understanding of common pathologies such as spinal disorders. The current study therefore aimed at the comparative evaluation of the Epionics SPINE system, a portable device for measuring sagittal lumbar back motion during functional activities. Twenty healthy participants were therefore evaluated with the Epionics SPINE and a Vicon motion capture system in two identical separate research visits. They performed the following activities: standing, sitting, chair rising, box lifting, walking, running and a counter movement jump (CMJ). Lumbar lordosis angles were extracted as continuous values as well as average and range of motion (ROM) parameters. Agreement between the systems was evaluated using Bland-Altman analyses, whereas within- and between-session reliability were assessed using intraclass correlation coefficients (ICC) and minimal detectable changes (MDC). The analysis showed excellent agreement between the systems for chair rising, box lifting and CMJ with a systematic underestimation of lumbar lordosis angles during walking and running. Reliability was moderate to high for all continuous and discrete parameters (ICC>=0.62), except for ROM during running (ICC=0.29). MDC values were generally below 15{\deg}, except for CMJ (peak values up to 20{\deg} within and 25{\deg} between the sessions). The Epionics SPINE system performed similarly to a Vicon motion capture system for measuring lumbar lordosis angles during functional activities and showed high consistency within and between measurement sessions. These findings can serve researchers and clinicians as a bench mark for future investigations using the system in populations with spinal pathologies.