Measuring lumbar spinal motion during functional activities with the Epionics SPINE system: a comparative evaluation and reliability study

Quantifying spinal motion during functional activities may contribute to a better understanding of common pathologies such as spinal disorders. Therefore, the current study aimed at the comparative evaluation of the Epionics SPINE system, a portable and cost-effective device for measuring sagittal lumbar movement during functional activities. Twenty healthy participants were therefore evaluated with the Epionics SPINE and a Vicon motion analysis 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). Sagittal plane lumbar spine 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°, except for CMJ (peak values up to 20° within and 25° 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.