Biomechanical Rationale for the Development of Atlantoaxial Instability and Basilar Invagination in Patients with Occipitalization of the Atlas: A Finite Element Analysis.

Objective: Occipitalization of the atlas (OA) often is associated with atlantoaxial dislocation and basilar invagination. The purpose of this study is to determine the biomechanical difference between normal and OA conditions in the craniovertebral junction and to further explore the rationale for development of atlantoaxial dislocation and basilar invagination using the finite element model (FEM).

Methods: A ligamentous, nonlinear, sliding-contact, 3-dimensional FEM of the occipitoatlantoaxial complex was generated.