Frei Hanspeter, Oxland Thomas R, Nolte Lutz P
Department of Orthopaedics, Maurice E Müller Institute for Biomechanics, University of Bern, Murtenstrasse 35, P.O. Box 30, 3010 Bern, Switzerland.
J Orthop Res. 2002 Nov;20(6):1333-8. doi: 10.1016/S0736-0266(02)00058-X.
The mechanical properties of the human spine have been studied extensively in compression, but there remains a lack of fundamental data in shear. The overall goal of this study was to contrast the mechanics of the thoracolumbar functional spinal unit (FSU) under compression and shear-type loads by evaluating endplate deformation, disc pressures, and kinematics between the different loading types. Eleven T12-L1 and one L1-L2 human FSUs were tested. Compression loads consisted of pure compression, extension-compression, flexion-compression, lateral left and right compression applied individually to a maximum of 500 N. Shear loading consisted of posterior, anterior, left, and right shear to a maximum of 500 N. Intervertebral motions, disc pressure, and vertebral body deformations were recorded for all loads. The deformations were measured using strain gauge rosettes at three points on the inferior vertebral body and one on the superior endplate of the inferior vertebra. The disc pressures and endplate deformations measured were significantly less in shear loading compared to compression and did not change significantly with the type of compression load. Vertebral rim strains were generally greater under shear loading compared with compression. The mechanics of load transfer in compression was the production of high disc pressures which were not linearly correlated with the central endplate deformation. In shear, the mechanism appears to be via the annulus fibrosus without the development of significant disc pressure. These differences between compression and shear loading may have implications for injury mechanisms in the thoracolumbar spine.
人体脊柱的力学特性在压缩方面已得到广泛研究，但在剪切方面仍缺乏基础数据。本研究的总体目标是通过评估不同载荷类型下的终板变形、椎间盘压力和运动学，对比胸腰段功能性脊柱单元（FSU）在压缩和剪切型载荷作用下的力学特性。对11个T12 - L1和1个L1 - L2人体FSU进行了测试。压缩载荷包括纯压缩、伸展 - 压缩、屈曲 - 压缩、单独施加的左侧和右侧横向压缩，最大至500 N。剪切载荷包括后向、前向、左侧和右侧剪切，最大至500 N。记录所有载荷下的椎间运动、椎间盘压力和椎体变形。使用应变片在椎体下方的三个点和下方椎体上终板的一个点测量变形。与压缩相比，剪切载荷下测量的椎间盘压力和终板变形明显更小，并且不会随压缩载荷类型而显著变化。与压缩相比，剪切载荷下椎体边缘应变通常更大。压缩时的载荷传递机制是产生高椎间盘压力，其与中央终板变形并非线性相关。在剪切时，机制似乎是通过纤维环，而不会产生显著的椎间盘压力。压缩和剪切载荷之间的这些差异可能对胸腰段脊柱的损伤机制有影响。
