- 學位論文
後側腰椎椎體間融合術於鄰近節椎間盤與小面關節之有限元素分析
Finite Element Analysis of Adjacent Intervertebral Disc and Facet Joint Degeneration in Posterior Lumbar Interbody Fusion
摘要
脊椎病變是現代人常見的疾病之一，臨床報告指出，術後雖可改善病患不適，但長時間追蹤發現病患會有小面關節增生、鄰近節椎間盤加速退化與椎弓釘斷裂之現象發生，導致病患需再次開刀。推測可能是腰椎椎體間融合術導致腰椎生物力學改變所引起的併發症，因此本研究的目的是使用有限元素模擬後側腰椎椎體間融合術結合脊椎內固定器與椎間融合器植入後之情形，針對鄰近節椎間盤與小面關節軟骨探討其退化的生物力學影響。 本研究模型包括皮質骨、海綿骨、薦椎、骨塊、纖維環、髓核、終板、小面關節軟骨、脊椎內固定器、椎間融合器與韌帶部分。在模型L4-L5間植入脊椎內固定器與椎間融合器模型，以模擬後側腰椎骨融合情形。負載條件則在L2椎體上端給予10N-m的曲屈、伸展、側彎、旋轉的力矩。共有四組分析參數進行比較:(1)椎間融合器數量與位置的影響 (2)四種不同椎板保留情形 (3)有無填補人工骨塊及使用自體骨代替椎間融合器植入 (4) 加入薦椎之影響；其中四種不同椎板保留情形，分為椎板保留二分之一、三分之一、四分之一以及不保留。結果發現在椎間融合器置於中間具有最佳的生物力學表現。四種不同椎板保留組別中可看出椎板保留二分之一模型其小面關節軟骨變形量、鄰近節纖維環與皮質骨受力情形具有較好表現；而使用自體骨頭合併植入人工骨塊組在各組比較下也是最佳之情形。加入薦椎模型後，發現在運動範圍上有增加之現象，在小面關節軟骨、鄰近節纖維環及L4-L5皮質骨其數值均有下降的趨勢。五種不同植入方式之組別與對照組比較，發現術後活動度均有減少之現象；進行L2-L3與L3-L4節的活動度比較，發現有使用人工骨塊的模型，其鄰近節的活動度明顯低於未使用的組別，證明人工骨塊的使用可有效降低鄰近節的退化產生。從上述結果發現當椎間融合器放置於中間、椎板保留二分之一、使用自體骨及人工骨塊植入與加入薦椎模型之情形下有著最佳生物力學表現。
並列摘要
Spinal lesion is one of the common diseases of modern people. Clinical reports indicated that the patient’s discomfort situation can be improved by surgery, but some phenomena of hypertrophy in facet joint, accelerated degeneration of adjacent disc or pedicle screw fracture were discovered after a long time to cause patient’s re-surgery. Complications may be affected by lumbar biomechanical changes after lumbar interbody fusion. Therefore, the purpose of this study is to use finite element analysis to investigate the biomechanical effects of degradation of adjacent disc and facet joint in the rear lumbar interbody fusion combined with spinal fixation device and interbody fusion cage. The finite element models were consisted of cortical bone, cancellous bone, sacrum, bone graft, annulus, nucleus, endplate, cartilage of facet joint, spinal fixation device, interbody fusion cage and ligaments. The interbody fusion cage was implanted between L4 and L5 spine and using spinal fixation device to fix to simulate the rear lumbar spine bone fusion. Loading condition of 10N-m was applied at the top of L2 vertebral for four movements of flexion, extension, lateral bending and rotation. Four types of parameters were considered to investigate biomechanical effects of the rear lumbar interbody fusion model including the number and location of interbody fusion cage, four resection types of lamina reserved, effects with and without bone graft and autogenous bone instead of intervertebral fusion cage, and influence of sacral structure. The four resection types of lamina reserved were lamina retain in half, one-third, one-fourth, and resected all. The result showed that the best biomechanical behaviors of single cage were located at the central position. Furthermore, the FE model combined with lamina reservations in half could provide the less cartilage deformation of facet joint and uniform stress distribution of annlus and cortical bone, the same effect of the best biomechanics was also detected in the model of parameter of bone graft and autogenous bone. The sacral structure was added in the rear lumbar interbody fusion model to increase the range of motion, but the evaluating indices were decrease trend in the cartilage of facet joint, adjacent of annlus and L4-L5 cortical bone. For comparing five implantation models and control model, the result revealed that range of motion in five implantation models were less than the normal spinal model. For further investigating ROM difference between L2-L3 and L3-L4 segment, the ROM was significantly decrease in the models of usage with the bone graft than that of without bone graft, the function of the bone graft was evidenced to decrease the degradation of adjacent spinal segment. The result conclude that the best parametric-combination model of the lumbar interbody fusion was the interbody fusion cage located at the central region, the lamina retaining in half, usage of autologous and bone graft and sacral structure applied.