Generating a finite element model of the cervical spine: Estimating muscle forces and internal loads

There are different approaches to Predict the nonlinear moment–rotation relationship and evaluate internal loads and muscle forces of the human cervical spine. In this study a geometrically accurate, nonlinear finite element model of C0–C7 was developed using CT images of the human cervical spine. This model was used to derive the moment–rotation responses of the cervical spine, under physiological moments of 0.33, 0.5, 1.0, 1.5 and 2.0 Nm for flexion/extension in the sagittal plane, lateral bending in the frontal plane and axial rotation. Moreover, the results from the finite element model were used to calculate muscle forces that contribute in equilibrium of the head during rotations in the sagittal and frontal planes. To achieve this, a biomechanical model and the optimization algorithm were used to determine the relationship between required muscle forces and neck angle for the quasi-static condition. Finally, muscle forces were exerted on the finite element model to calculate internal forces. The results showed an excessive increase in internal loads by increasing the angle of rotation in all directions. In conclusion, this study provides evidence of higher cervical spine internal loads in non-neutral head postures, which can be a risk factor for neck pain and arthritis.