Finite element modeling of vertebral body stapling applied for the correction of idiopathic scoliosis: preliminary results.

Endoscopic vertebral body stapling is an innovative technique intended to treat adolescent idiopathic scoliosis, but the optimal instrumentation design is not yet established. The objective was to simulate the immediate correction obtained from two stapling configurations. A parametric finite element model of a typical right thoracic scoliotic spine (Cobb 21 degrees ) was developed using geometrical and mechanical data from the literature. Staple insertion and closing were modeled. The intra-operative lateral decubitus and standing positions were taken into account. Two implant configurations, varying the number of staples per vertebra, were simulated. The major correction (9 degrees ) came by simulating the intra-operative posture. The immediate Cobb angle correction due to the staples alone was less then 1 degrees for both configurations. However, the staples helped maintain the correction obtained by the intra-operative posture when the post-operative standing position was simulated. Next steps are to validate the model using surgical cases, implement growth modulation modeling, improve lateral decubitus modeling, and analyze different vertebral stapling strategies for different scoliotic curves.