Finite Element Study of Lean Anterior Cervical Plating Instrumentation Designs

Abstract

This study reports a finite element model for predicting stresses at the critical locations of an Anterior cervical plating instrumentation due to routine neck movements of flexion, extension, lateral bending, axial rotation and a combination thereof. The model's simplicity lies in the remote mapping of the applied moments directly at the anchoring locations of the plating system construct without the complexities of invoking the cervical spinal architecture. The model's utility is demonstrated by evaluating the performance of two different 'lean' plating system designs, viz. 'uniformly lean plate' and 'lean plate-with-stubs'. The axial screw loads were found to be under 150N for all the neck movement cases simulated, well below the pull-out force of the screws typically employed in anterior cervical plating systems. The von Mises stress at the critical locations, viz., plate-screwhole interfaces and screwhead surfaces, was found to be below 150MPa. The contact stress at the anchor locations of the plate with the vertebral body was determined to be 31.8% higher for the 'lean plate-with-stubs' than the 'uniformly lean plate'. The higher contact stress in the former appears to be adequate to induce changes in bone remodelling, favouring osseointegration.