Biomechanical Evaluation of Different Bone Grafts Combined with Instrumentations in Anterior Thoracolumbar Fusion

• Main Authors: Jun-Wen Yu, 余俊文
• Other Authors: Wen-Pin Chen
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/03302385840622265017

碩士 === 中原大學 === 醫學工程研究所 === 91 === For lesion involved in the anterior and/or middle column of the spine, an anterior approach is adequate for curetting the lesion and restoring spinal stability. Long-term spinal stability still relies on the integrity of the bone fusion. The most important thing in spinal stabilization procedure is not instrumentation itself but finally solid fusion of bone graft. In spinal fusion surgery, bone grafts and instrumentations are commonly used to enhance bone fusion and to provide stability. In practice, autologous bone graft, such as, iliac bone crest is most often adopted. In anterior approach of thoracolumbar vertebral surgery, the ribs are often dissected and may be an alternative choice for bone graft besides iliac bone. The purpose of this study was to use a validated finite element model to evaluate the effects of using iliac bone, one rib or two-rib bone graft combined with anterior or posterior instrumentations in thoracolumbar interbody fusion surgery, under the condition of axial compression, lateral bending, flexion, extension and rotation. According to the analysis results, under the conditions of axial compression or flexion moment, the results of the two-rib and iliac bone graft conditions were similar. There was stress concentration on the one-rib graft. We suggest that under the condition of solid fusion, two-rib bone graft could be an alternative choice. For the results of instrumentations, both anterior and posterior instrumentations could reduce the stress on the interbody bone graft. They could provide initial support right after operation and prevent early collapse of bone graft. The constructs of the instrumentations were stronger if the screws penetrate the opposite side cortex of the vertebral body. Also the two screws were better when positioned triangulated than parallel. The cross link between the rods could strengthen the constructs of the instrumentations under axial rotation.