摘要
本文之主要工作為改良椎籠之幾何形狀，使其能單獨使用，避免在同時使用兩個椎籠所出現不預期的問題。依手術方式不同考量，分為小承載面積椎籠與大承載面積椎籠兩種設計：(1)大承載面積椎籠有三個孔洞可放置補骨，適用於前方椎骨融合手術；(2)小承載面積椎籠有兩個孔洞可放置補骨，適用於後方椎骨融合手術。然後探討此二不同承載面積的椎籠在生物力學與穩定性方面的表現。 利用有限元素法分析椎籠承受純壓、彎曲與扭轉各項負載結合的最大von Mises stress與L4椎體最大下陷位移量，分析方法為：(1)椎籠結合L4-L5椎骨；(2)結合不同尺寸後方固定器；(3)結合單邊或雙邊後方固定器；(4)不同位置植入小承載面積椎籠。 結果以下列三種型式作比較︰(1)椎籠有無結合後方固定器的比較；(2)小承載面積椎籠植入位置不同的比較；(3)不同情況下的後方固定器所承受最大von Mises stress。 經由有限元素分析獲得的結果可以發現，使用大承載面積椎籠接觸表面積較大，故在穩定性與生物力學方面較優於小承載面積椎籠。不過小承載面積椎籠結合後方固定器情況下，有明顯改善其應力過大的現象。使用小承載面積椎籠配合後方固定器，螺絲小徑直徑值須大於6mm。小承載面積椎籠實體測試，結果發現結合夾具的情況下，負載為15000N導致材料塑性變形。另外無結合夾具時，負載為10000N導致材料塑性變形。
關鍵字
聚乙醚酮椎籠並列摘要
In order to avoid the unexpected problems in using a pair of cages in bone fusion, the geometric shapes of cages were designed that they can be used alone as the implant in the operation of intervertebral disc. In account to the convenient consideration in operation, two types of cages were designed, namely, small bearing area and big bearing area in the condtions that: (1) the cage with small bearing area had two holes for implanting graft and applied to posterior spinal fusion; (2) the cage with big bearing area had three holes for implanting graft and applied to anterior spinal fusion. This study analyzes the stability and biomechanics of the spine under the use of the cage of different bearing areas individually. The finite element method was used to analyze the mechanical behaviors of the vertebrae in the following cases. (1) Cage with L4-L5 vertebra, (2) cage with posterior fixator of different size, (3)cage with single or double posterior fixator, (4) different implanted positions of the cage with small bearing area and under comb ined loads of compress, flexion and torsion. The results are compared under the following headings: (1)cage with or without posterior fixator; (2)different implanted positions of the cage with small bearing area; (3)max. von Mises stress of posterior fixator under different situation. The results show that the cage with big bearing area are better than the cages with small bearing area under the considerations of stability and biomechanics. However, the high stresses in the cages with small bearing area could be reduced by the use of posterior fixator, while cooperating with posterior fixator, the minor diameter of the screw should be greater than 6mm. In entity tests, 2-hole cages with the jigs attained to plastic deformation at a load of 15000N. When in the condition of without jigs, they attained to plastic deformation at a load of 10000N.