臨床上當脊椎發生椎間盤病變或是腰椎神經壓迫等問題，醫生就會進行外科手術治療，其中一種手術方式為前位腰椎骨融合手術(ALIF)，此手術會先將病變椎間盤切除，接著在椎體間植入移植骨或椎籠來維持椎體間高度，最後以前方板型固定器將患部脊椎做固定以達穩定椎體及促進骨融合的效果。但是此手術後仍然會有植入物失效問題與併發症的產生。然而前方板型固定器的固定穩定度可能會受到骨螺絲不同植入角度的影響，先前有已學者藉由改變骨螺絲植入角度來探討此問題，但是結論並不一致。因此，本研究目的為探討不同骨螺絲植入角度對於腰椎骨融合固定穩定度之影響。
首先使用SolidWorks建立三維腰椎實體模型，接著匯入ANSYS Workbench完成非線性有限元素模型並進行求解分析。此研究分別利用田口參數化方法進行數值分析與類神經網路搭配遺傳演算法進行最佳化分析，最後再將數值分析結果與生物力學實驗結果進行驗證討論。
數值分析結果發現，縱剖面(SI平面)的貢獻度遠大於橫切面(ML平面)，其中又以腰椎第五節之縱剖面(L5SI平面)為最重要設計因子，最佳化分析結果發現，類神經網路搭配遺傳演算法所取得的最佳化設計優於田口參數化方法獲得的設計，透過類神經遺傳演算法取得的最佳化設計在L4SI平面傾角為15°、L4ML平面傾角為15°、L5SI平面傾角為-8.2°、L5ML平面傾角為15°。另外，生物力學實驗結果發現，最佳化設計確實能提供椎體最好的固定穩定度，且實驗結果與有限元素分析結果的相關係數為0.909。此生物力學研究結果可以提供給外科醫生做術前參考，另外利用數值分析法可為前方板型固定器設計提供新的設計概念給相關工程師做參考。

Spinal disc degeneration or lumbar nerve root compression can be treated by surgical operations. One of surgical operations is anterior lumbar interbody fusion (ALIF). In this surgical procedure, the lumbar disc is incised and removed. Then, an intervertebral cage or a small block of bone graft is placed between the vertebrae. Finally, an anterior vertebral plate is held in front of lumbar vertebrae by bone screws. However, the clinical complications of anterior lumbar vertebral plate system still occur. The fixation stability of anterior vertebral plates might be affected by different screw orientation. Past studies have tried to improve this clinical performance by changing the screw orientation, but their conclusions are inconsistency. Thus, the purpose of this study was to investigate the fixation stability of vertebral plate with variable-angle screws for the anterior lumbar interbody fusion surgery .
Three-dimensional solid models of the spinal implants were developed by using SolidWorks, and the nonlinear finite element models were developed to investigate the fixation stability by using ANSYS Workbench. The parametric study and the optimization study of anterior vertebral plate systems were conducted by using Taguchi robust design methods and neurogenetic algorithms, respectively. The results of the numerical studies were validated using the biomechanical tests.
For the parameteric study, the consequence of this research was that the contribution of sagittal plane (SI plane) was more influential than transverse plane (ML plane), and L5SI was particularly important design parameter. For the optimal study, optimum design obtained from neurogenetic algorithms was superior to that obtained from Taguchi Methods. The optimum design obtained from neurogenetic algorithms was 15°in SI plane of L4 vertebra, 15° in ML plane of L4 vertebra, -8.2° in SI plane of L5 vertebra, and 15°in ML plane of L5 vertebra. For the biomechanical tests, the numerical results could be validated and the correlation coefficient between the numerical models and the experimental tests was 0.909. The results of this study could directly provide the surgical suggestion and biomechanical rationale to orthopedic surgeons. In addition, those numerical models could also be used to evaluate a new design of anterior vertebral plate.

[1] 骨骼肌肉徒手保健 http://seaturtle365.pixnet.net
[2] 許達夫醫師自然醫療網 http://www.nsshu.com
[3] 香港腰脊物理治療中心 http://www.backclinic.com.hk
[4] University of MARYLAND MEDICAL CENTER http://www.umm.edu
[5] Total disc arthroplasty http://www.spinesupport.org
[6] Kotani, Y., Cunningham B.W., Parker L.M., Kanayama M, and McAfee P.C., "Static and Fatigue Biomechanical Properties of Anterior Thoracolumbar Instrumentation Systems," Spine, vol. 24,pp. 261-266,1999.
[7] Lowery, G.L., McDonough,R.F. The Significance of Hardware Failure in Anterior Cervical Plate Fixation: Patients With 2- to 7-Year Follow-up. Spine, Vol. 23, pp.181-186 ,1998.
[8] Jin D., Qu D., Chen J., and Zhang H., "One-stage anterior interbody autografting and instrumentation in primary surgical management of thoracolumbar spinal tuberculosis," Spine, Vol. 13, No. 2, pp.114-121, 2004.
[9] Benli İ., Acaroğlu E., Akalin S., Kiş M., Duman E., and Un A., "Anterior radical debridement and anterior instrumentation in tuberculosis spondylitis," Spine, Vol. 12, No. 2, pp. 224-234, 2003.
[10] Hsu, C.C., Chao, C.K., Wang, J.L., Hou, S.M., Tsai, Y.T., Lin, J., Increase of pullout strength of spinal pedicle screws with conical core: biomechanical tests and finite element analyses. Journal of Orthopaedic Research Vol.23,788-794,2005.
[11] Lill, C.A., Schneider, E., Goldhahn, J., Haslemann, A., Zeifang, F., Mechanical performance of cylindrical and dual core pedicle screws in calf and human vertebrae. Archives of orthopaedic and trauma surgery Vol. 126,pp. 686-694, 2006.
[12] Mehta, H., Santos, E., Ledonio, C., Sembrano, J., Ellingson, A., Pare, P., Murrell, B., Nuckley, D.J. Biomechanical analysis of pedicle screw thread differential design in an osteoporotic cadavermodel. Clinical Biomechanics doi:10.1016/j.clinbiomech.2011.1010.1004 ,2011.
[13] Netter F.H., "Atlas of Human Anatomy. 2nd ed. ,"ICON Learning Systems,2002.
[14] 廖柏舜,「使用田口方法與有限元素分析法於前方板型固定器之拉出強度參數化設計」,碩士論文，國立台灣科技大學，台北，2010。
[15] Krayenbuhl, N., Schneider, C., Landolt, H., Fandino, J. Use of an empty, plasmapore-covered titanium cage for interbody fusion after anterior cervical microdiscectomy. Journal of Clinical Neuroscience Vol.15, pp.11-17 , 2008.
[16] Hojo, Y., Kotani, Y., Ito, M., Abumi, K., Kadosawa, T., Shikinami, Y., Minami, A. A biomechanical and histological evaluation of a bioresorbable lumbar interbody fusion cage. Biomaterials Vol. 26,pp. 2643-2651, 2005.
[17] Silber, J.S., Anderson, D.G., Daffner, S.D., Brislin, B.T., Leland, J.M., Hilibrand, A.S., Vaccaro, A.R., Albert, T.J. Donor Site Morbidity After Anterior Iliac Crest Bone Harvest for Single-Level Anterior Cervical Discectomy and Fusion. Spine, Vol. 28,pp. 134-139,2003.
[18] Medical Demonstrative Evidence Library http://powershowz.medicalillustration.com
[19] VIRNIGIA SPINE INSTITUTE http://www.spinemd.com
[20] Cunningham B.W., S.J., Shono Y., McAfee PC."Static and cyclical biomechanical analysis of pedicle screw and spinal constructs," Spine, Vol. 18,pp. 1677-1688,1993.
[21] Hollowell, J.P., Reinartz, J., Pintar, F.A., Morgese, V., Maiman, D.J. Failure of synthes anterior cervical fixation device by fracture of Morscher screws: a biomechanical study. Journal of Spinal Disorders & Techniques Vol. 7, pp.120-125, 1994.
[22] Lowery, G.L., McDonough, R.F. The Significance of Hardware Failure in Anterior Cervical Plate Fixation: Patients With 2- to 7-Year Follow-up. Spine ,Vol. 23,pp. 181-186,1998.
[23] Kotani.Y., Cunningham B.W., Parker L.M., Kanayama M. and McAfee PC."Static and Fatigue Biomechanical Properties of Anterior Thoracolumbar Instrumentation Systems," Spine, Vol. 24,pp. 1406-1413,1999.
[24] Rohlmann A., Zander T., Bergmann G."Comparison of biomechanical effects of posterior and anterior spine-stabilizing implants," Spine, Vol. 14, pp. 445-453,2005.
[25] Rodriguez-Olaverri, J.C., Hasharoni, A., DeWal, H., Nuzzo, R.M., Kummer, F.J., Errico, T.J. The effect of end screw orientation on the stability of anterior instrumentation in cyclic lateral bending.Spine, Vol. 5, 554-557,2005.
[26] Zehnder. S., Bledsoe, J.G., Puryear, A. The effects of screw orientation in severely osteoporotic bone: A comparison with locked plating. Clinical Biomechanics Vol. 24, 589-594,2009.
[27] Hussain,M, Natarajan, R.N., Fayyazi, A.H., Braaksma, B.R., Andersson G, B.J., An, H.S."Screw angulation affects bone-screw stresses and bone graft load sharing in anterior cervical corpectomy fussion with a rigid screw-plate construct: a finite element model study," Spine, Vol.9,pp.1016-1023,2009.
[28] Lee D.H., Lee J.S., Yi J.S. , Cho W., Lukas P. Zebala, K. Riew D.,"Anterior cervical plating technique to prevent adjacent-level ssification development," Spine ,In Press, Corrected Proof,2013.
[29] Synthes Spine, West Chester, PA, USA，ATB Anterior Tension Band Plate，Surgical technique.
[30] Memphis, TN, USA，LT cage Lumber Tapered Fusion Device，Surgical Technique.
[31] 徐慶琪，骨螺絲之結構設計與生物力學分析，國立台灣科技大學，博士論文，台北，2005。
[32] 康淵、陳信吉，ANSYS入門，全華科技圖書有限公司，台北市，2006。
[33] Netter F.H.,"Atlas of Human Anatomy.2nd ed.," ICON Learning Systems,2002.
[34] 蔡國忠，ANSYS Workbench有限元素分析及工程應用，加樺國際圖書有限公司，臺北縣，2008。
[35] Shin-Hao, Zheng-Cheng Zhong, Chen-Sheng Chen, Wen-Jer Chen, Chinghua Hung"Biomechanical comparison between lumber disc arthroplasty and fusion" Journal of Medical Engineering & Physics,Vol. 31,pp 244-253 (2009)
[36] Yang-Hwei Tsuang,Yueh-Feng Chiang,Chih-Yi Hung, Hung-Wen Wei, Chang-Hung Huang, Cheng-Kung Cheng,,"Comparison of cage application modality in posterior lumbar interbody fusion with posterior instrumentation -A finite element study",Journal of Medical Engineering&Physics，Vol. 31,pp565-570,2009.
[37] 丁志華、戴寶通, "田口實驗計畫法簡介（Ι）" 毫微米通訊, vol. 8, No. 3, pp.7-11,2001.
[38] 張斐章，類神經網路 東華書局，2005。
[39] Benzel E. C., "Biomechanics of spine Stablilzation, American Association of Neurological Surgeons", Illinois, 2001.
[40] Haid R.W., Foley K.T., Rodts G.E., Barnes B.," The Cervical Spine Study Group anterior cervical plate nomenclature" The Journal of Neurosurgery, Vol.12, pp.1-6,2002.
[41] Mayr M.T., Subach B. R., Comey C.H., Rodts G.E., Haid R.W.," Cervical spinal stenosis: outcome after anterior corpectomy, allograft reconstruction, and instrumentation" The Journal of Neurosurgery, Vol. 96, pp.10-16,2002.