Lopez-Valdes Francisco J, Lau Sabrina, Riley Patrick, Lamp John, Kent Richard
University of Virginia - Center for Applied Biomechanics.
Ann Adv Automot Med. 2011;55:193-206.
A growing body of literature points out the relevance of the thoracic spine dynamics in understanding the thorax-restraint interaction as well as in determining the kinematics of the head and cervical spine. This study characterizes the dynamic response in bending of eight human spinal specimens (4 pediatric: ages 7 and 15 years, 4 adult: ages 48 and 52 years) from two sections along the thoracic spine (T2-T4 and T7-T9). Each specimen consisted of three vertebral bodies connected by the corresponding intervertebral discs. All ligaments were preserved in the preparation with the exception of the inter-transverse ligament. Specimens were exposed to a series of five dynamic bending ramp-and-hold tests with varying amplitudes at a nominal rate of 2 rad/s. After this battery of tests, failure experiments were conducted. The 7-year-old specimen showed the lowest tolerance to a moment (T2-T4: 12.1 Nm; T7-T9: 11.6 Nm) with no significant reduction of the relative rotation between the vertebrae. The 15-year-old failure tolerance was comparable to that of the adult specimens. Failure of the adult specimens occurred within a wide range at the T2-T4 thoracic section (23.3 Nm- 53.0 Nm) while it was circumscribed to the interval 48.3 Nm-52.5 Nm for the T7-T9 section. The series of dynamic ramp-and-hold were used to assess two different scaling methods (mass scaling and SAE scaling). Neither method was able to capture the stiffness, peak moment and relaxation characteristics exhibited by the pediatric specimens.
越来越多的文献指出，胸椎动力学在理解胸部与约束装置的相互作用以及确定头部和颈椎的运动学方面具有重要意义。本研究对取自胸椎两个节段（T2 - T4和T7 - T9）的八个人类脊柱标本（4个儿童：7岁和15岁，4个成人：48岁和52岁）的弯曲动态响应进行了表征。每个标本由三个通过相应椎间盘连接的椎体组成。除横突间韧带外，所有韧带在制备过程中均得以保留。标本以2 rad/s的标称速率接受一系列五次不同幅度的动态弯曲斜坡-保持试验。在这一系列试验之后，进行了失效实验。7岁的标本对力矩的耐受性最低（T2 - T4：12.1 Nm；T7 - T9：11.6 Nm），椎体之间的相对旋转没有明显减小。15岁标本的失效耐受性与成人标本相当。成人标本在T2 - T4胸椎节段的较宽范围内发生失效（23.3 Nm - 53.0 Nm），而在T7 - T9节段则限定在48.3 Nm - 52.5 Nm的区间内。这一系列动态斜坡-保持试验用于评估两种不同的缩放方法（质量缩放和SAE缩放）。两种方法均无法捕捉儿童标本所表现出的刚度、峰值力矩和松弛特性。
