不同設計之前位腰椎椎間融合器之有限元素分析

Finite Element Analysis of Different Designs of Anterior Lumbar Interbody Fusion Cages

林建宇(Chien-Yu Lin)

指導教授 ： 陳文斌

中原大學/工學院/醫學工程研究所/碩士(2006年)

https://doi.org/10.6840/cycu200600668

摘要

單純植入椎間融合器是否可以用來治療慢性下背疼痛及恢復椎間盤高度，目前並無定論，有些手術方式會加入固定裝置以提高椎體穩定度及骨融合率，本研究目的是利用有限元素分析法，探討植入不同椎間融合器對應力分佈的影響。由L3-L4原始椎體模型修改四種8度之矩型椎間融合器及一種0度之圓柱型椎間融合器，給予150N模擬自重而植入物與椎體界面摩擦係數設定為0.4，在L3椎體給予10Nm力矩，分別模擬前彎、伸展、側彎及扭轉負載，並固定L4椎體底部所有節點。計算植入不同椎間融合器在不同負載情況下，對小面關節應力、植入物與終板界面滑動距離與上椎體旋轉角度的影響。模擬結果證明有最大椎間融合器與椎體之接觸面積，可以降低小面關節應力及融合器滑動距離。在承受垂直、前彎、伸展、側彎及扭轉負載下，單純植入複合式椎間融合器較其它四種椎間融合器加入後固定器，擁有較小滑動量。計算在各種負載情況下之上椎體旋轉角度，單純植入複合式椎間融合器在承受前彎及扭轉負載下，可以降低椎體旋轉角度，但是在承受伸展及側彎負載下與植入其它融合器並無顯著差異，而在任一負載情況下加入後側固定器皆可以降低椎體旋轉角度。

關鍵字

椎間融合器 ； 複合式椎間融合器 ； 有限元素分析 ； 後側固定器

並列摘要

Initial promise of stand-alone interbody fusion cage to treat chronic backache and restore disc height has not been maintained. Others use a posterior spinal fixation in conjunction with interbody spacers to enhance the stability and promote fusion rate. The objective of this study was to use finite element analysis (FEA) to investigate the stress distribution after the insertion of several interbody fusion spacers. Four rectangular 8° interbody fusion cage models and one cylinder 0° interbody fusion cage model created according to the anatomic geometry the intact L4-5 model were used to simulate a 150N compressive preload with interfacial friction coefficient of 0.4 for the study of interaction between implants and vertebral body. Then L3 vertebral body was subjected to 10-Nm moment in flexion, extension, lateral bending and torsion, respectively. The nodes on the bottom surface of L4 were constrained. The changes of contact stress on the facet joint, maximum slip displacement of the implants on the endplate, and rotational angle of the upper vertebra were investigated under different loading conditions. Simulation results demonstrated less facet contact stress and slip displacement under the maximal interface contact between interbody spacers and vertebral bodies. The stand-alone two-part fusion cage has optimal slip behavior under compression, flexion, extension, lateral bending and torsion, as compared with the other four interbody cages even with additional on posterior fixation. The stand-alone two-part cage had the lowest rotational angle in flexion and torsion, but had no prominent difference of rotational angle in extension and lateral bending. The rotational angle decreased following the addition of posterior fixation under various loadings.

並列關鍵字

Interbody spacer ； Finite element analysis ； Two-part fusion cage

參考文獻

1. Lee, C.K., Langrana, N.A., 1984. Lumbosacral spinal fusion: a biomechanical study. Spine 9, 574-581.

2. Hibbs, R.A., 1911. An operation for progressive spinal deformity. NY Med. J. 21, 1013–1016.

3. Albee, F.H., 1911. Transplantation of a portion of the tibia into the spine for Pott’s disease. J. Am Med Assoc 57, 855-858.

4. Chandler, F.A., 1929. Spinal fusion operations in the treatment of low back and sciatic pain. JAMA 93, 1447.

5. Mixter, W.J., Barr, J.S., 1934. Rupture of the intervertebral disc with involvement of the spinal canal. N Engl J Med. 211, 210.