Beckner M A, Heggeness M H, Doherty B J
Baylor College of Medicine, Institute for Spinal Disorders, Houston, Texas, USA.
Spine (Phila Pa 1976). 1998 Sep 1;23(17):1832-6. doi: 10.1097/00007632-199809010-00005.
Fifteen specimens of the first cervical vertebra were tested by the application of pure tensile forces to failure. Seven specimens had intact transverse ligaments, and eight had transection of the transverse ligament before testing. Specimens were tested to failure by the rapid application of laterally directed tensile force to the ring; this force then was exerted through the lateral masses to simulate the mechanism of injury for this fracture as proposed by Jefferson.
To measure the biomechanical characteristics of the C1 ring, including the fracture patterns created with tensile loading, and to describe the influence of the transverse ligament on the behavior of the ring as it failed under tension.
Jefferson fractures have been reproduced in the laboratory by subjecting head and neck preparations to axial load. However, no previous detailed biomechanical studies of the fracture characteristics of the isolated C1 vertebra have been reported.
Specimens were tested to failure by rapid application of laterally directed tensile forces to the ring.
Eleven two-part and three three-part fractures occurred. The mean tensile strength of the atlas was found to be 2,280 N. The average deformation required to fracture the C1 ring was 1.57 mm. The total energy absorbed by the ring averaged 1.99 N-m. There was no statistically difference between those specimens with the transverse ligament intact and those without a transverse ligament.
The results of this study show that fractures of the C1 ring of greater than two parts can occur with pure tensile loading. The ring will fracture with as little as 1 mm of deformation.
对15个第一颈椎标本施加纯拉力直至破坏进行测试。7个标本的横韧带完整，8个标本在测试前横韧带已横断。通过向环快速施加侧向拉力直至破坏来测试标本；然后该力通过侧块施加，以模拟杰斐逊提出的这种骨折的损伤机制。
测量C1环的生物力学特性，包括拉伸加载产生的骨折模式，并描述横韧带在环在拉伸下破坏时对其行为的影响。
通过对头颈部标本施加轴向载荷，已在实验室再现了杰斐逊骨折。然而，此前尚未有关于孤立C1椎体骨折特征的详细生物力学研究报道。
通过向环快速施加侧向拉力直至破坏来测试标本。
出现了11例两部分骨折和3例三部分骨折。寰椎的平均拉伸强度为2280N。使C1环骨折所需的平均变形为1.57mm。环吸收的总能量平均为1.99N·m。横韧带完整的标本与无横韧带的标本之间无统计学差异。
本研究结果表明，纯拉伸加载可导致C1环出现超过两部分的骨折。环在仅1mm的变形时就会骨折。
