Wearable sensor performance for clinical motion tracking of the lumbar spine

Abstract

Inertial measurement units (IMUs) have potential to be integrated into clinical assessments of movement-related disorders of the spine. This study evaluated 2 Mbientlab MetaMotionR IMUs relative to Vicon motion capture equipment in tracking 3D spine motion during 35 cycles of constrained repetitive spine flexion-extension (FE) in 10 participants. Root-mean-square error (RMSE) was low in all anatomical planes (RMSE ≤ 2.43°). Pearson’s correlation coefficient was strong in the FE and lateral bend (LB) planes (R ≥ 0.746), and weak-to-moderate in the axial twist (AT) plane (0.343 ≤ R ≤ 0.679). Additionally, there was very strong correlation between range of motion measurements in the FE plane (ICC2,1 = 0.99), and a wide range from weak to strong in the LB and AT planes (0.239 ≤ ICC2,1 ≤ 0.980). This study reveals that the IMUs perform well in tracking motion in the primary movement plane, and can be used for planar assessments of movement quality.