The Biomechanical Response of Cervical Spine under Different Follower Loads

The follower load is a synergy of the mimicking the human muscle tissue. It can improve load-carrying capacity of the human cervical spine and play an important part in maintaining the stability of cervical spine. Currently, the studies of the influence of a follower load on biomechanics of cervical spine is still not perfect. Therefore, this paper used the finite element (FE) modeling method to investigate the biomechanical response of cervical spine under different follower loads. The range of motion (ROM) of and intradiscal pressure (IDP) in the cervical spine were important parameters reflecting the condition of the cervical spine. So a three-dimensional (3D) nonlinear finite element model of the cervical spine (C3-C7) was built and validated. Under different follower loads (0 N, 50 N, 100 N, 150 N), a moment of 1 Nm was applied in the three anatomical planes to study the the influence of the follower load on the range of motion and intradiscal pressure in cervical spine. The results indicated that follower load reduced the ROM of cervical spine in extension, and in other postures increased the ROM. The most significant effect of the follower load on cervical spine was in torsion (55%), lateral bending (50%) and flexion (17%). In all postures, the IDP of cervical spine increased with the follower load increased, at the same the IDP changed nonlinearly with the follower load increased.