冲击载荷造成椎管内压力变化与脊髓损伤程度的评估

Changes of the pressure in the vertebral canal and evaluation of spinal cord injuries in spinal section subjected to impact

目的 观察脊柱遭受轴向撞击时椎管内的压力变化，从撞击－压力变化－脊髓损伤的角度分析脊柱骨折类型与脊髓损伤程度间的关系，为脊髓损伤程度的早期评估提供实验依据。方法 应用 BIM－Ⅰ 型立式生物撞击机高速准静态轴向加载和应力遮挡技术建立脊椎爆裂型骨折模型，观察 8具新鲜尸体的脊柱标本 T10～ L 4节段受垂直撞击瞬间椎管内的压力变化，将大体解剖观察与放射影像学技术相结合，记录脊柱骨折类型及脊柱损伤程度。结果 发生脊椎爆裂型骨折的 4具标本均在撞击瞬间记录到椎管内高大的正向压力波 (A型波 )，其压力峰值与后柱损伤程度有关，后柱有损伤的峰值较小，无损伤的峰值较大。脊柱损伤主要表现为椎体爆裂型骨折、椎管骨性及纤维性结构的严重破坏。 2具放射影像学检查无异常发现的标本，椎管内记录到正向和负向压力波（ B型波），大体解剖标本可见受损椎体中柱有少量骨髓溢出。结论 椎管内压力的波型与椎管结构的变形或破坏有关；椎管内压力峰值与椎管阻塞程度为非线性关系，与后柱结构是否损伤有关。

Objective To observe the changes of the pressure in vertebral canal subjected to impact and to analyze the relationship between the type of spinal fracture and the severity of spinal cord injuries. Methods The experimental model of spinal burst fracture was produced with type BIM－Ⅰ bio－ impact machine, in which the techniques of high velocity vertical loading in static pattern and stress shielding were adopted. The vertebral section of T10－ L 4 taken from fresh cadevers was impacted and the changes of the pressure in the vertebral canal were observed. Combined with the gross and radiography examination, the types and severity of spinal fracture were studied. Results Great positive pressure wave(wave A) was recorded in the vertebral canal in 4 vertebral samples with burst fracture. The peak value of pressure was correlated with the severity of posterior column injuries. Generally, the peak value of pressure was low in the samples with posterior column injuries, however, it was high in the samples without injuries. The predominant features of fracture were burst fracture of vertebral body, with severe destruction of skeletal and fiber structure of vertebral canal. Positive and negative pressure waves(wave B) were recorded in 2 vertebral samples in which no significant abnormal changes were found by radiographic examination, however, little liquid effusion in vertebral body was found in gross examination. Conclusion The type of the pressure wave in the vertebral canal was related to the deformation or the destruction of vertebral canal structure. The peak value of the intrathecal pressure was non－ linearly related to obstruction in the vertebral canal, but related to the posterior column injuries.