The use of disharmonic motion curves in problems of the cervical spine.

Cervical spine motion was investigated by three-dimensional electrogoniometry in 257 asymptomatic volunteers and in 32 patients with cervical disc hernia or whiplash syndrome. Maximal ranges of main and coupled motions were considered. Motion curves were analysed qualitatively and using fitting of sixth degree polynomials. Motion ranges obtained were in agreement with previous observations. Significant differences between patients and volunteers concerned several primary and coupled components but not all. Qualitatively, patients displayed less harmonic curves, with irregularities and plateau-like appearances. Root mean square differences between data and fit were significantly modified in patients. Although cervical spine motion ranges may remain within normal limits in patients, motion patterns were altered qualitatively and quantitatively. Motion pattern analysis might prove a useful discrimination parameter in patients in whom anatomical lesions are not clearly identifiable.