Clarke Elizabeth C, Appleyard Richard C, Bilston Lynne E
Department of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, Sydney, Australia.
Spine (Phila Pa 1976). 2007 Dec 15;32(26):2970-9. doi: 10.1097/BRS.0b013e31815cde16.
Dynamic triaxial biomechanical testing of immature and mature ovine spine motion segments.
To compare torque-deflection parameters of mature and immature spine motion segments and to investigate whether scaling relationships apply between mature and immature motion segment torque-deflection responses.
While previous studies have examined the cervical region in a limited number of loading directions, a comprehensive multiaxial study of the response of the pediatric spine at all 3 spinal levels (cervical, thoracic, and lumbar) has not been performed.
Motion segments from cervical, thoracic, and lumbar levels were tested under moment application about 3 axes for newborn and 2-year-old sheep. Range of motion, neutral zone, and stiffness were calculated for each motion segment and compared for immature and mature spine.
Immature spine motion segments exhibited a significantly larger range of motion (P < 0.001) and neutral zone (P < 0.001) and significantly lower stiffness (P < 0.001) in comparison to mature spine segments about the 3 moment axes, at the 3 spinal levels tested. There were statistically significant interactions between specimen age and the moment axis and/or spinal level for some torque-deflection parameters.
The significantly greater neutral zone of immature spine suggests greater ligament laxity. Significantly higher range of motion and lower stiffness of the immature spine may be implicated in spinal cord injury mechanisms and implies a change in relative tolerance of the spine to damage with spinal maturity. Significant statistical interactions between spinal maturity and moment axis or motion segment level suggest that scaling torque-deflection parameters from mature to immature spine may not be appropriate.
未成熟和成熟绵羊脊柱运动节段的动态三轴生物力学测试。
比较成熟和未成熟脊柱运动节段的扭矩-位移参数，并研究成熟和未成熟运动节段扭矩-位移反应之间是否存在比例关系。
虽然先前的研究在有限数量的加载方向上研究了颈椎区域，但尚未对小儿脊柱在所有三个脊柱水平（颈椎、胸椎和腰椎）的反应进行全面的多轴研究。
对新生和2岁绵羊的颈椎、胸椎和腰椎水平的运动节段在绕三个轴施加力矩的情况下进行测试。计算每个运动节段的运动范围、中性区和刚度，并比较未成熟和成熟脊柱的情况。
在测试的三个脊柱水平上，与成熟脊柱节段相比，未成熟脊柱运动节段在绕三个力矩轴时表现出明显更大的运动范围（P < 0.001）和中性区（P < 0.001），以及明显更低的刚度（P < 0.001）。对于一些扭矩-位移参数，标本年龄与力矩轴和/或脊柱水平之间存在统计学上的显著交互作用。
未成熟脊柱明显更大的中性区表明韧带松弛度更高。未成熟脊柱明显更高的运动范围和更低的刚度可能与脊髓损伤机制有关，这意味着随着脊柱成熟，脊柱对损伤的相对耐受性发生了变化。脊柱成熟度与力矩轴或运动节段水平之间的显著统计交互作用表明，从成熟脊柱到未成熟脊柱按比例缩放扭矩-位移参数可能不合适。
