Biomechanics Research Laboratory, Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, New Haven, CT 06520, USA.
Spine (Phila Pa 1976). 2012 May 20;37(12):1022-9. doi: 10.1097/BRS.0b013e31823fd92d.
An in vitro biomechanical study.
To investigate atlas injury mechanisms due to horizontally aligned head-first impacts of a cadaveric neck model and to document atlas fracture patterns and associated injuries.
Experimental atlas injuries have been created by applying compression or radial forces to isolated C1 vertebrae, dropping weight or applying sagittal moments to the upper cervical spine segments, or vertical drop testing of head-neck specimens or whole cadavers. Atlas injuries that commonly occur due to horizontally aligned head-first impacts have not been previously investigated.
Horizontally aligned head-first impacts into a padded barrier were simulated at 4.1 m/s, using a human cadaver neck model mounted horizontally to a torso-equivalent mass on a sled and carrying a surrogate head. Atlantal radial force was computed using head and neck load cell data. Postimpact dissection documented atlas and associated injuries. Average atlantal radial force peaks and their occurrence times were statistically compared (P < 0.05) among the first local and global peaks using paired t tests.
The first average local peak in radial atlantal force was significantly smaller (1240 vs. 2747 N) and occurred significantly earlier (24 ms vs. 46 ms) than the global force peak. Atlas injuries consisted of either 3- or 4-part burst fractures or incomplete lateral mass fracture unilaterally. Associated injuries included bony avulsion of the transverse ligament unilaterally and fractures of the occipital condyles, superior facets of the axis, or odontoid.
The results indicated that the varied atlas fracture patterns were due primarily to radial forces causing outward lateral expansion of its lateral masses. Anterior and posterior arch fracture locations are dependent, in part, upon the cross-sectional arch dimensions. Transverse ligament rupture or bony avulsion is likely associated with real-life atlantal burst fractures.
一项体外生物力学研究。
研究尸体颈部模型头高脚低位水平撞击导致寰椎损伤的机制，并记录寰椎骨折模式及相关损伤。
寰椎损伤实验已通过向单独的 C1 椎体施加压缩或放射状力、向颈上段脊柱施加重量或矢状面力矩、或对头部-颈部标本或整个尸体进行垂直跌落测试来实现。但先前尚未研究过常见的因头高脚低位水平撞击导致的寰椎损伤。
使用水平安装在雪橇上的躯干等效质量上的人体尸体颈部模型和替代头部，以 4.1m/s 的速度模拟头高脚低位水平撞击软垫屏障。使用头部和颈部负载细胞数据计算寰椎的放射状力。撞击后解剖记录寰椎和相关损伤。使用配对 t 检验对首次局部和整体峰值的平均寰椎放射状力峰值及其发生时间进行统计学比较（P<0.05）。
首次局部平均放射状寰椎力峰值明显较小（1240N 比 2747N）且出现时间更早（24ms 比 46ms）。寰椎损伤包括 3 或 4 部分爆裂骨折或单侧不完全侧块骨折。相关损伤包括单侧横韧带的骨撕脱和枕骨髁、枢椎上关节面或齿状突骨折。
结果表明，不同的寰椎骨折模式主要是由于放射状力导致其侧块向外侧向扩张所致。前弓和后弓骨折的位置部分取决于弓的横截面积。横韧带断裂或骨撕脱可能与实际的寰椎爆裂骨折有关。
