Wireless orientation sensors: their suitability to measure head movement for neck pain assessment.

The purpose of this study was to verify the performance and suitability of new generation 3D wireless orientations sensors to measure cervical range of movement against a criterion standard instrument, an electromagnetic motion analysis system (Fastrak-Polhemus). The wireless orientation sensor (InertiaCube 3) consists of 9 motion-sensing elements: 3 accelerometers, 3 angular velocity rate transducers and 3 magnetometers. Measurements of cervical range of motion in each primary plane, left-lateral flexion, flexion and left rotation were directly compared from both systems in 10 normal asymptomatic subjects. Results showed very high cross-correlations (.99-.97) and low average root mean square errors (0.7-2.5 degrees). We conclude that orientation sensors are a valid, accurate and suitable device for obtaining cervical joint ranges of motion in the primary plane of movement.