Posterior cervical fixation following laminectomy: a stress analysis of three techniques.

The aim of this study was to compare the following three main fixation techniques: pedicle screw (PS) technique, lateral mass screw (LS) technique, and transarticular screw (TS) technique. A detailed, geometrically accurate, nonlinear C3-C7 FE model had been successfully developed and validated. Then three finite element (FE) models were reconstructed by different fixation techniques following C4-C6 level laminectomy. A compressive preload of 74 N combined with a pure moment of 1.8 Nm in flexion, extension, left-right lateral bending, and left-right axial rotation was applied to the models. The results showed that maximum von Mises stress on the fixation devices was much higher in the FE models of TS technique, compared with the models of PS and LS techniques. Furthermore, the screws inserted by TS technique had high stress concentration at the middle part of the screws. Screw inserted by PS and LS techniques had high stress concentration at the actual cap-rod-screw interface. The highest level of maximal stress was obtained with the fixation device of the TS technique. TS technique induces noticeable differences in the stress compared to the posterior cervical fixation technique, regarding the higher stress level on fixation devices.