不同棘突間植入物在脊椎活動度與椎間盤壓力之生物力學研究

Biomechanical studies of different interspinous process devices on the spinal flexibility and intradiscal pressure

徐新怡(Hsin-Yi Hsu)

指導教授 ： 陳文斌 ； 莊仕勇

國立臺北科技大學/機電學院/機電整合研究所/碩士(2010年)

https://doi.org/10.6841/NTUT.2010.00318

摘要

近年來，由於非融合手術蓬勃發展，棘突間植入物常被用來治療腰椎狹窄症，其主要功能為回復神經孔尺寸以及提供腰椎後彎穩定度。但是其相關禁忌症尚未明確，且針對各類型之棘突間植入物對腰椎生物力學的影響，尚未被充分研究。因此，本研究將結合體外實驗與有限元素分析，探討不同設計之棘突間植入物之生物力學機轉與響應。
體外實驗，將豬腰椎(L1-L6)試片分作三組(正常組、移除小面關節之缺陷組以及植入棘突間植入物組)，並給予10Nm模擬後彎負載。探討之棘突間植入物包括:Coflex、X-STOP、Wallis以及DIAM，並評估椎節活動度以及椎間盤壓力。有限元素分析部分，利用電腦斷層掃描影像建構人體完整腰椎之有限元素模型(L1-S1)，並施予腰椎7.5Nm之彎曲負載以及自重，模擬前屈、後彎、側彎以及扭轉等動作，隨後進行缺陷組以及植入棘突間植入物組之模擬，並評估各植體稱開神經孔之效果、椎節活動度、椎間盤應力以及可能造成棘突骨折的風險。
體外實驗結果顯示，後彎負載下移除小面關節組使手術節活動度增加35%，而植入各植體後均表現相似之效果，皆能夠提升椎節之穩定度，並提供降低椎間盤壓力之能力。分析結果發現，各植體於後彎負載下，皆能夠回復病徵節之神經孔與椎孔尺寸，而穩定手術椎節活動度之能力，最低與最高為Coflex(67%)與Wallis(82%)，同時降低椎間盤應力之能力最低與最高為Coflex(69%)與Wallis(80%)。另外，於前屈及扭轉負載下，具有束帶的植體-Wallis以及DIAM，則另提供椎節些微之穩定度。除此之外，植入各植體於後彎負載下所造成鄰近棘突之負載，尚無造成術後棘突骨折之風險。
實驗與有限元素分析結果顯示，各植體對腰椎生物力學之影響有共同之趨勢：於後彎負載下，提供椎節良好穩定度以及分散椎間盤壓力。

關鍵字

腰椎 ； 棘突間植入物 ； 有限元素分析

並列摘要

For the past few years, interspinous process decompression (IPD) devices are common as a treatment for lumbar spinal stenosis (LSS) due to a non-fusion surgery has become more and more popular. The efficacies of implanting IPD device are to restore foraminal dimension and provide stability in extension. However, the relative contraindications of IPD devices remain unclear, and the biomechanical effect of lumbar spine with various types of IPD devices has not been thoroughly investigated. Therefore, the aim of this study is to investigate the biomechanical mechanism and the response of different IPD implant designs by using finite element analysis combined with in vitro experiment.
For the experimental study, the porcine lumbar spine specimens (L1-L6) were divided into three conditions (intact, total facetectomy and implantation) and tested with 10Nm extension moments. Four different interspinous implants (Coflex, X-STOP, Wallis and DIAM) were included in the implantation group, and the Range of motion (ROM) and intradiscal pressure were evaluated. In the finite element analysis (FEA), a three-dimensional geometrical and mechanical accurate finite element model of human lumbosacral spine (L1-S1) was developed from 3D geometrical data of visible human project, and pure moments of 7.5 Nm were applied with preload in flexion, extension, lateral bending and torsion following total facetectomy and implantation. Foramina dimension, ROM, intradiscal stress and the risks of spinous process failure were assessed in the present study.
For the experimental results, the defect caused an increase in ROM by 35% about in extension at the implanted level. Implantation had similar effects with all implants that compensated the instability caused by the defect. Similarly the intradiscal pressure after implantation was much smaller than that of the defect specimen during extension. For the FEA, IPD devices restored the foraminal dimension at implanted level, and a motion decrease of 67% for Coflex up to 82% for Wallis and intradiscal stress decrease of 69% for Coflex up to 80% for Wallis compared to the defect were calculated during extension. For flexion and torsion, the models caused a moderate decrease of ROM for Wallis and DIAM with two ligatures compared to the defect state. Furthermore, there was no risk of spinous process fracture by implanting all four IPD devices during extension.
Good agreements between the FEA and the experiments are shown that all tested insterspinous implants had similar effects on the biomechanical response: they strongly stabilized and reduced the instradiscal pressure in extension.

並列關鍵字

lumbar spine ； interspinous process device ； finite element analysis

參考文獻

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