Comparison of visual and ultrasound based techniques to measure head repositioning in healthy and neck-pain subjects.

Three-dimensional (3D) ultrasound based (US) and usual Revel visual techniques were compared to measure head repositioning ability in 41 healthy subjects and 41 subjects with neck pain. Head repositioning absolute value of the global error (AE) was calculated by both techniques after active head rotations. The AE was 3.