A validated finite-element-model of human cervical spine - Description andfirst application.

Aim: To generate a finite-element model of the human cervical spine and eva luate the first application of the model to the analysis of new c-spine imp lants. Methods: CT-data were used to generate a three-dimensional, anisotro phic, linear model of the human C4-C7 motion segments using the software AN SYS 5.4. As a next step, anterior cervical fusion and plate fixation using mono- and bi-cortical screws was simulated in the model. Loading of the fin ite-element models was simulated using pure moments of +/- 2.5 Nm in flexio n/extension, axial left/right rotation, and left/right lateral bending. The range of motion was calculated. The results were compared to the results o f an in vitro study using human cadaveric c-spine segments C4-C7, with the same implants and moments on both the intact and surgically treated specime ns. Results: The results obtained by the finite-element model were always w ithin one standard deviation of the results of the in vitro study. Conclusi on: keeping in mind the simplifications of such a mathematical model, it ma y be used for a first analysis of the shape of new c-spine implants or to p redict the initial stability of a new device.