Joint position error after neck protraction-retraction movements in healthy office workers: a cross-sectional study

Since the upper cervical spine (UCS) has been regarded to be distinct from the lower cervical spine (LCS), joint position error (JPE) needs to be tested separately for both regions. The purpose of this study was to investigate the JPE after cervical protraction/retraction movements, involving opposite movements of extension and flexion for the UCS and LCS. These movements are frequently performed during office work. Cervical JPEs were tracked in thirty healthy office workers while performing four tests of cervical pro-retraction movements with variations in vision and movement direction, and assessed using the Kinect head tracker (Microsoft Corp), placed in front of each participant. The JPE was expressed in constant (CE), absolute (AE) and variable errors (VE). Multilevel linear models evaluated main and interaction effects of vision, movement direction, cervical region and sex. Slightly larger JPEs have been found in the UCS. Vision showed no effect on any outcome variable. No effect exceeded typical measurement errors reported for the Kinect head tracker. This study showed, that JPEs after pro-retraction movements of the head and neck may differ for UCS and LCS. The differences were small and not beyond measurement error reported for the Kinect.