Biomechanical Study of Long-Segment Spine Instrumentation: The Effect of Cross-Links

摘要

Objective To develop FE models of osteotomized spine and evaluate whether cross-link (CL) improves the instrumentation stiffness and decrease the risk of complications. Methods Firstly, a finite element model without CL was established based on CT images of postoperative male patients with thoracolumbar kyphosis. Secondly, five models were established according to the different numbers and positions of CL. Four loading conditions (flexion, extension, lateral bending, and axial rotation) were applied to the model. The range of motion (ROM), the maximum value and distribution of the implants, and vertebrae stress were compared between models. Results With number of CL increasing, the ROM of instrumented segments was reduced. When loading axial rotation condition, the ROM was reduced by 21.98%. The peak stresses were located on rods during axial rotation, on proximal pedicle screws during flexion, and on the osteotomy site during extension and lateral bending. The CLs had an effect of dispersing stress concentration. Conclusions The application of CLs is able to enhance the rigidity of the construct. With the number of CL increasing, the ROM of the construct is reducing, especially in axial rotation. CLs can also make stress concentration dispersed.