Yoganandan N, Larson S J, Pintar F, Maiman D J, Reinartz J, Sances A
Department of Neurosurgery, Medical College of Wisconsin, Milwaukee.
Neurosurgery. 1990 Dec;27(6):873-80; discussion 880-1. doi: 10.1097/00006123-199012000-00003.
This investigation was conducted to determine alterations in the biomechanical strength and stiffness characteristics of the lumbar spine fixated with Steffee instrumentation. Comparative studies of these parameters were conducted using seven lumbar columns from fresh human cadavers. Three runs were conducted on each T12-L5 column: control, injured, and fixated. The specimens were loaded under the compression-flexion mode until failure (control run) and then reloaded (injury run) to the failure deformation determined in the control run. Screw/plates were then inserted one level proximal and distal to injury, and the specimens were reloaded (fixation run). Radiographs were taken before and after each trial. Data on deformation and force histories were gathered. The load-deflection response of the injured and fixated specimens were bimodal with two representative stiffnesses. Control failure loads and stiffnesses were higher than those for the injured (P less than 0.001) or fixated (P less than 0.01) spine. Initial stiffness was significantly higher for the fixated than for injured columns (P less than 0.001), but the final stiffnesses were similar. The increase in the initial stiffness in the fixated specimen compared to the injured specimen indicates the strength added to the posterior region of the spine. The relatively smaller alteration in the final stiffness between the fixated and the injured columns, corresponding to the load shared by the anterior column, may suggest that, above a critical strain level, the anterior column absorbs a higher portion of the external load and posterior fixation may be inadequate as sole treatment in trauma.
本研究旨在确定采用Steffee器械固定的腰椎生物力学强度和刚度特性的变化。使用来自新鲜人类尸体的七节腰椎柱对这些参数进行了比较研究。对每个T12-L5柱进行了三次测试：对照、损伤和固定。标本在压缩-屈曲模式下加载直至破坏（对照测试），然后重新加载（损伤测试）至对照测试中确定的破坏变形。然后在损伤节段的近端和远端各一个节段插入螺钉/钢板，并对标本重新加载（固定测试）。每次测试前后均拍摄X线片。收集了变形和力历程的数据。损伤和固定标本的载荷-挠度响应呈双峰，具有两种代表性的刚度。对照的破坏载荷和刚度高于损伤（P<0.001）或固定（P<0.01）的脊柱。固定柱的初始刚度明显高于损伤柱（P<0.001），但最终刚度相似。与损伤标本相比，固定标本初始刚度的增加表明脊柱后部区域增加了强度。固定柱和损伤柱之间最终刚度的相对较小变化，对应于前柱分担的载荷，可能表明，在临界应变水平以上，前柱吸收了更高比例的外部载荷，后路固定作为创伤的唯一治疗方法可能不足。
