Finite element (FE) analysis is a useful tool in spinal biomechanics because it can be used to study external and internal parameters in the intact as well as degenerated/instrumented spine. The geometry of the cervical spine is complex, making it difficult and time consuming to develop subject-specific hexahedral meshes. Additionally, subject-specific validation experiments are ideal but challenging due to difficulty in determining the soft tissue material properties. The cervical spine behaves nonlinearly; consequently, it is important to validate models by comparing the entire loading curve instead of the endpoint response.;We developed interactive multiblock methods for subject-specific hexahedral meshing of the cervical spine. The technique is user friendly and decreases the amount of time and effort required for subject-specific mesh development. Using our methods, we created a cervical spine C27 FE model. Experimental flexibility tests (+/-1 Nm flexion-extension, lateral bending, and axial rotation) were performed on the same specimen which was used to develop the model. The model's soft tissue properties were calibrated using varying properties from the literature, and the model was validated by comparing its nonlinear response to the experimental data.;The calibrated finite element model agreed favorably with the experimental results. In flexion, right lateral bending, and left axial rotation the shape of the moment rotation curve matched well for the entire loading curve. The most notable differences were in extension and right axial rotation near the endpoints, and left lateral bending at moments greater than 0.5 Nm. Coupled motions and individual level ranges of motion (ROMs) were also compared.;The validated model was used to study the adjacent level effects of simulated fusion using the hybrid loading protocol. ROMs and stresses at the non-fused levels increased in the fusion model as compared to the intact.;Despite the challenges and limitations associated with finite element modeling of the spine, we have successfully developed and validated a C27 model and have demonstrated its ability to assist in understanding the biomechanical effects of spinal interventions. The model can be used in additional studies to aid in the design of spinal devices.
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