Dolan P, Adams M A
Department of Anatomy, University of Bristol, Southwell Street, BS2 8EJ, Bristol, UK.
Clin Biomech (Bristol). 2001;16 Suppl 1:S8-S16. doi: 10.1016/s0268-0033(00)00096-6.
Mathematical models are often used to quantify the overall forces and moments acting on the lumbar spine. However, if the purpose of the research is to explain how spinal tissues can be injured, it is necessary to distribute the overall forces and moments between (and within) different spinal structures, because it is the concentration of force which causes injury, and elicits pain. This paper reviews recent experimental evidence concerning the distribution of forces and moments acting on the lumbar spine. Lordotic postures increase loading of the posterior annulus and apophyseal joints, whereas moderately flexed postures tend to equalise compressive stress across the disc, and unload the apophyseal joints. Sustained compression reduces the volume and pressure of the nucleus pulposus, while increasing compressive stresses in the annulus and neural arch. Sustained compression also reduces disc height, giving some slack to collagen fibres in the intervertebral disc and ligaments, and causing them to resist bending less. Disc degeneration has a similar effect on disc height, and stress distributions. On the other hand, discs and ligaments can be subjected to greater bending moments following a period of sustained or repetitive bending, because sustained bending impairs the normal protective reflex from the back muscles, and repetitive bending fatigues the back muscles, reducing their ability to protect the spine. Incorporating this information into mathematical models will make them better able to identify which activities are most likely to injure the lumbar spine in life.
数学模型常被用于量化作用于腰椎的整体力和力矩。然而，如果研究目的是解释脊柱组织如何受伤，就有必要将整体力和力矩在不同脊柱结构之间（以及内部）进行分配，因为是力的集中导致了损伤并引发疼痛。本文回顾了有关作用于腰椎的力和力矩分布的最新实验证据。脊柱前凸姿势会增加后纵韧带和小关节的负荷，而适度屈曲姿势往往会使椎间盘上的压应力均匀化，并减轻小关节的负荷。持续压缩会减小髓核的体积和压力，同时增加纤维环和神经弓中的压应力。持续压缩还会降低椎间盘高度，使椎间盘和韧带中的胶原纤维松弛，导致它们抵抗弯曲的能力降低。椎间盘退变对椎间盘高度和应力分布有类似影响。另一方面，在经历一段时间的持续或反复弯曲后，椎间盘和韧带可能会承受更大的弯矩，因为持续弯曲会损害背部肌肉的正常保护反射，反复弯曲会使背部肌肉疲劳，降低它们保护脊柱的能力。将这些信息纳入数学模型将使它们更能识别生活中哪些活动最有可能损伤腰椎。
