Development of spine proprioception testing using motion capture analysis

Background: While the Vicon system is the gold standard in motion analysis, it has never been used to analyse spinal proprioception. We developed a skin marker system to evaluate regional differences in spinal proprioception in people with and without scoliosis.

Objectives: To determine the reliability of a novel skin marker system in evaluating spinal proprioception in healthy volunteers.

Methods: Four volunteers without back pain or scoliosis were recruited. Reflective markers were attached to participants’ chin, right scapula, and six spinous processes (C7, T3, T7, T12, L3, L5). Participants were blindfolded and instructed to reposition to the reference upright sitting posture twice, while the Vicon system captured the motions. Reliability was evaluated by intraclass correlation coefficient (ICC). Absolute error was defined as the magnitude of difference in angles between repositioning and the reference trial. Relative error included directionality to the angular deviation.

Results: T7-T12-L3 angle (sagittal) showed excellent reliability on absolute error (ICC=0.917), standard deviation (SD) of absolute error (ICC=0.938) and SD of relative error (ICC=0.939); good reliability on relative error (ICC=0.801). L3-L5- vertical angle (coronal) also showed moderate reliability on absolute error (ICC=0.682), relative error (ICC=0.532), SD of absolute error (ICC=0.644) and SD of relative error (ICC=0.665). While both chin-C7-T3 angle (sagittal) and T3-T7-T12 angle (coronal) reported with an ICC range greater than 1.5.

Discussion: The marker system demonstrated good to excellent reliability in measuring spinal proprioception although within-subject variations in regional spinal proprioception were noted. Future studies with a larger sample size are warranted to confirm this observation. Copyright © 2021 the Hong Kong Orthopaedic Association.