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Axial loading of the head-neck complex in a head first collision is a major cause of traumatic cervical spine and spinal cord injuries. It has been suggested (McElhaney, 1989) that cervical spine fracture is not observed when the head and neck are forced into extension. To evaluate this posture as an injury risk reducing strategy and to estimate the loading imposed on the structures of each cervical segment a quasi-static analytical sagittal plane model of the cervical spine in extension and compression was developed in conjunction with an instrumented physical test model. The modelled structures included the anterior longitudinal ligament (ALL) the Longus Colli (Lco) and Longus Capitis (Lca) muscles, the anterior musculature of the neck (Ma), the intervertebral discs (IVD) and the spinous processes (Sp).

Cervical spine trauma from head first collisions was studied using a Hybrid III head and neck (AHN) fitted with a force transducer. An analytical model (Bioneck II) which accounted for the anatomy and geometry of the human cervical spine enabled compressive loads at any vertebral level to be determined. Model inputs included shear and compressive forces and moments from the transducer and kinematics of the cervical elements of the AHN. For trials against a fixed barrier compression was reduced by 25% in the upper cervical spine and was increased by 30% in the lower cervical spine when compared to transducer values. The use of the AHN can be enhanced with the Bioneck II model, and when used together they offer promise for further investigation of cervical spine trauma.