- 學位論文
半開門式椎板整形術後椎板擴張對於頸椎穩定性與脊神經拉伸之影響
Effects of Laminae Expansion on Cervical Stability and Spinal Nerve Tension after open-door Laminoplasty
摘要
簡介:椎板切除輔以融合術及椎板整形術常用於治療多節的頸椎神經根脊髓炎。為了減少神經所受的壓迫，椎板切除輔以融合術其後脊突、椎板以及周圍韌帶在術中會被移除。然而，由於頸椎活動被過度限制，在鄰近節會出現提早退化的現象。椎板整形術則保留大部分後側組織，並於神經受壓端進行椎板打開的動作，而對側則挖出溝槽當作支點端。椎板打開的同時，可以減緩神經所受之壓迫。至於椎板打開的大小並無特定的標準，過大的開口角度雖有較好的減壓效果避免神經根脊髓炎的再發生，卻可能導致C5神經根麻痺的機率增加。手術節的上節後側韌帶像是脊上、脊間以及黃韌帶的切除可以使得椎板的打開較為容易，然而韌帶的切除會否對整體的穩定性造成影響仍然未知。 目的:本實驗目的為找出合適的椎板開口角度能有效的減壓，減少C5神經根麻痺的發生，以及韌帶保留對頸椎穩定性的影響。 材料與方法 (a)C5神經根過度拉伸 以每分鐘5毫米的速度進行位移控制的拉伸測試找出神經根的初始區(Toe region)。初始區的定義為力量位移曲線圖最初的區域，代表生物組織被拉緊前呈現鬆散狀態的區域。(b)安全的開口角度 八個單節試樣保留神經以及神經根，並藉由植入矽膠塊進行50%頸椎狹窄模擬。當椎板在打開的同時，量測神經截面積以及神經根的變形。合適的開口角度能達到30%的神經減壓，並且從(a)的結果避免神經根過度拉伸。(c)頸椎穩定性的評估 八個多節試樣於健康狀態(C3-C7)以2Nm的大小進行前彎、後仰還有側彎的動作。之後做C4-C6節椎板開口30度的椎板整形術並保留韌帶、C4-C6節椎板開口30度的椎板整形術並切除韌帶、C4-C6節椎板開口45度的椎板整形術並切除韌帶以及椎板切除輔以融合術。開口角度30度為前面結果(b)而得，而45度則是根據臨床的經驗而得。在各節椎骨植入反光式的旗標，用於活動度的追蹤與量測。 結果:本實驗從拉伸測試的結果指出，神經根拉伸量達初始區的平均為2.0mm。由後縱韌帶模擬組別的數據可看出，神經面積恢復30%時所需的最小角度為27度以及避免神經根過度拉伸的角度安全值為31度，因此，定義出開口角度30度為建議的手術角度。穩定度測試方面，前彎的總活動度在LP30組比起健康組有下降的趨勢， C3-C4韌帶切除後則有顯著上升，而融合組與各組相比，皆有顯著下降除了LP30組之外。後仰及側彎的總活動度，趨勢與前彎一致但未出現顯著差異，只有在融合組後與各組相比同樣有顯著下降。從各節的相對活動度來看，前彎活動度於C3-C4節在韌帶切除前後有顯著性的上升。而C4-C5節在健康組與LP30組間的活動度下降最為顯著，韌帶切除後與LP30組出現顯著差異。手術節(C4-C6)的活動度於融合組過後皆有顯著的下降，鄰近節則因代償現象出現顯著的上升。後仰各節的相對活動度於C3-C4節在韌帶切除後也有上升的趨勢，但未達到顯著。C4-C5節在健康組與LP30組間同樣出現顯著差異，手術節於融合組後比起各組有顯著性下降。另外，鄰近節反而有下降趨勢，且沒有代償現象的出現。側彎手術節的活動度同樣在融合組後有明顯下降，而右側彎C3-C4節的活動度在韌帶切除後有顯著上升，C6-C7節則在融合組出現了顯著下降。 結論:本實驗發現有效的神經減壓並且避免神經根過度拉伸，開口30度為建議的椎板整形術。在穩定度測試方面，開口角度30度與43度於各方向活動度幾乎沒有差異，且同樣角度下C3-C4韌帶切除前後會明顯改變C3-C4及C4-C5節的活動度分布。而椎板整型術各組與椎板切除輔以融合術相比，活動度都較接近於健康組的狀態。
並列摘要
Objective: To investigate the effect of lamina open angle on the cervical stability and nerve root tension during expansion open-door laminoplasty (EOLP). Introduction: Multilevel cervical radiculomyelopathy is often treated with cervical laminectomy and fusion (CLF) or EOLP. For the CLF surgery, spinous process, laminae and surrounding ligaments of surgery level are removed to decrease compressive stress on spinal cord. However, the rigid fixation constrains movement of cervical spine, and the compensational range of motion (ROM) at adjacent level often leads to early disc degeneration. For the EOLP surgery, most of posterior elements of surgery levels are reserved. The procedures of EOLP begins with the opening of lamina at nerve compression side and creating a hinge groove at the contralateral side. The lamina were then flipped to release the pressure on spinal cord. There is no standard for the lamina open angle yet. Larger lamina open angle can better decompress the spinal cord and prevent myeloradiculopathy recurrence. However, the larger open angle may also increase the risk of C5 palsy. Posterior intersegmental ligaments above the surgery level, e.g., the supraspinous ligaments, interspinous ligaments and ligamentum flavum, are dissected for the easier operation of laminae expansion, especially for wider laminae expansion. However, the effect of ligament preservation on spinal stability remains unclear. The propose of this study is to find the suitable lamina open angle that can sufficiently decompresses spinal cord without causing C5 palsy and the effect of ligament preservation on cervical spine stability after EOLP and CLF surgeries. Material and Methods: (a) Threshold of C5 nerve-root overstretching. A displacement-controlled tensile test was performed at a speed of 5 mm/min to find the toe region of C5 nerve roots. Toe region is defined as the initial segment of force-deformation curve, where the deformation does not linearly increase with the applied force due to the laxity nature of biological tissue. (b) Safety margin of lamina open degree. Eight C5 vertebrae with preservation of spinal cord and nerve roots were dissected from 6-month-old pigs, and applied with 50% cervical stenosis simulation by inserting the silicon blocks into spinal canal. The cross-sectional area of spinal cord and nerve root deformation during lamina opening were measured pre and post the artificial stenosis. The suitable lamina open degree was estimated by overlapping the open angles which the decompression of spinal cord is more than 30% and threshold of nerve-root overstretching found from the results of protocol (a). (c) Evaluation of cervical stability after EOLP and CLF. Eight multilevel cervical spines (C3-C7) were dissected from 6-month old pigs. Intact specimens were applied with 2 Nm pure moment in flexion, extension, and lateral bending. Thereafter, the C4-C6 of specimens were sequentially applied with EOLP of 30-degree laminae opening with C3-4 ligaments preserved, EOLP of 30-degree laminae opening with C3-4 ligament removal, and EOLP of 45-degree laminae opening with C3-4 ligament removal and CLF. Stability tests were performed after every surgery simulations. In EOLP surgery, 30-degree laminae opening was defined as the lower limit of lamina open angle defined in Protocol (b), and the 45 degree opening was defined as upper limit for clinical practice. Light-reflection markers were inserted in each vertebra for motion tracking. The total ROM and intersegmental ROM of cervical spine were measured. Results. (a) The mean threshold of C5 nerve-root deformation was 2.01 mm. (b) The lamina open angle corresponding to the threshold of C5 nerve root deformation was 31 degree, and the lamina open angle that reaches 30% recovery of cross-sectional area of spinal cord was 27 degree. Hence, in protocol (c), the lamina open angle was 30° for narrow-opening EOLP, and 45° for wide-opening EOLP. (c) Total ROM. Among the four directions of motions, only the ROM of flexion was significantly affected by EOLP. The ROM of flexion slightly decreased after 30-degree EOLP. The removal of C3-4 posterior ligaments significantly increased ROM. The increase of laminae open angle further increased the ROM in flexion. All directions of ROMs decreased post CLF. Intersegmental ROM. After EOLPs, motions of C3-4 and C4-5 significantly altered during flexion and extension. Motions of other segments were similar to the intact level after each kinds of EOLP. During flexion, motions of C3-4 and C4-5 slightly decreased after 30-degree EOLP, significantly exceeded the intact level after excision of C3-4 intersegmental ligaments, and then remained the same after the increase of lamina open angle. Trend for intersegmental motion changing of all EOLP was similar to that in flexion. After CLF, the intersegmental ROMs of implanted segment (C4-5 & C5-6) were significantly lower than the intact level during flexion, extension and left/right lateral bending. Intersegmental ROMs of adjacent cranial segment (C3-4) and adjacent caudal segment (C6-7) significantly increased during flexion, but decreased during extension and lateral bending compared to the one in intact level. Conclusion: In this study, 30 degree lamina open angle was suggested be the range of EOLP that sufficiently decompress spinal cord and maintain cervical stability without violating C5 nerve root and compensation of adjacent intersegmental motions.