Biomechanical Analyses of Corpectomy and Anterior Cervical Plating: A FEM Study to Assess Stability, Implant and Bone Graft Stresses in Short and Long Constructs

Anterior corpectomy of the cervical vertebral body is an established procedure to decompress the spinal cord for cervical spondylotic myelopathy, traumatic and neoplastic cases. Following corpectomy at one or more levels, the spinal column is typically reconstructed by strut grafting and plating. Modern plate-screw fixation systems provide improved rigidity, but complications still may occur such as screw loosening, screw pull-out, nonunion, construct failure, and injuries to adjacent vital structures. The stability of the plate-screw constructs as wells as the stresses and strains in the implant and bone graft depend on many factors including the number of motion segments fused, presence of intermediate screws and loading direction. It is hypothesized that the shorter constructs provide greater stability and reduced stresses in the implant and bone graft as compared to longer constructs, and intermediate screws in the longer constructs improve the stability. This study will investigate the biomechanical effects of plate-screw fixation in both short and long anterior fusion constructs, using a validated multi-segment cervical finite element model.