Biomechanical Studies of Posterior Spinal Instrumentation System for Scoliosis-An Intact Porcine Spine Model

脊椎側彎症所使用之固定器械的生物力學研究—利用完整之豬脊椎模型

陳博光(Po-Quang Chen) ； 施啟明(Chi-Ming Shih) ； 鄭誠功(Cheng-Kung Cheng) ； 趙偉泰(Wei-Tai Jan) ； 吳志明(Chih-Ming Wu)

《Journal of Orthopaedic Surgery Taiwan》 7卷1期 (1990/03) Pp. 1-12

摘要

側彎的脊椎目前有很多種方式來矯正及固定。本研究以完整之豬脊椎取下，兩端固定，中間以路其桿、哈靈頓桿路其桿合併，哈靈頓桿加鋼絲或悉弟桿固定七節椎弓，固定後之脊椎，均以材料測試機測定其垂直壓力及彎曲時之強度。同時也測試固定部份之椎間皮變形量及受力時金屬桿所承受之分壓，以做手術之參加。
　　由實驗得知，在垂直壓力下，各種固定器械之強度均差不多。但數字顯示，路其桿及哈靈頓路其桿之合併最強。在彎曲測試，則以悉弟及哈靈頓及路其桿之合併最為強硬。又椎間之變形，以悉弟桿最小且最均勻。金屬桿所承受之分壓，均在30%以下。
　　由本實驗可知，以悉弟桿及哈靈頓查路其桿之合併最為強硬。但悉弟桿固定脊椎，其固定節數，應可減少上下兩節，因椎間皮受壓之變形小，故彎曲之上下端不必再延長，以接受固定。此優點可減少將來下背痛發生之機會。

並列摘要

In order to investigate the stiffness of the spinal constructs, an intact porcine spine was developed for the assembly of the 4 common implants we adopted for the scoliosis correction. There included Luque rod (LR), Harrington-Luque combination (HL), Harrington with sublamminar wiring (HSSI) and cotrel-Dubousset Instrumentation (C-D I) with or without cross-linking devices. Both axial compressive and flexion tests were performed on the servocontrolled testing machine (Hydropuls PSB 10).Cyclic compression test was conducted in force controlled mode at the range of 25 to 275N. cyclic flexion test was done in stroke-controlled mode with 25cm moment arm. Also, the deformation of the instrumentations were detected by strain gauges, while the displacements of body and disc were recorded “on line” by extensometers. The load-displacement behavior of the intact porcine spine showed different displacement patterns suggesting the unhomogenous and viscoelastic properties of the spines. HL and LR groups possessed higher compressive stiffness although the difference was not significant. HL and C-D I with cross-linking groups showed highest flexion moment, and LR was the weakest (p＜0.05). as to the disc deformation, C-D I groups showed fairly consistent and minimal displacement in both axial compression and flexion testings. The other groups showed larger deformation in both end disce. Stress shielding to the rod was estimated under 30% for flexion test.
CLINICAL RELEVANCE: The present studies suggest that both HL and C-D I constructs possess higher stiffness than other groups. Their correctability for idiopathic scoliosis was also better in our experience. The deformation of the discs under load was consistently minimal in the C-D I constructs, while the deformation, especially at both end discs, was high in other constructs. This suggests that extension of fixation segments on both ends of the scoliosis curvature is not necessary in the C-D I. thus the fixation and fusion segments can be shorter, which is of course beneficial to the patients. The effect due to stress shielding of the instrumentation needs further investigation.

並列關鍵字

biomechanical test ； porcine spine ； instrumentation