A technique for objective evaluation of the passive restraint characteristics of cervical orthoses

A six-degree of freedom spatial linkage which permits measurement of cervical spine stiffness and range of motion (ROM) is described. Using the apparatus, the ROM restriction capabilities and passive stiffness characteristics of cervical orthoses in flexion, extension, axial rotation and lateral bending may be directly evaluated and compared. Exponential regression using transformation of variables is used to model the data. The development of an accurate exponential regression model permits the direct comparison of stiffness and strain energy at a given angle of displacement for each loading condition. Thus deficiencies in the designs of orthoses will be readily identifiable and subsequent design improvements will be based on the mechanical properties of the orthoses opposed to only their ROM restriction capabilities.