Department of Orthopedic Surgery, Tokushima University Graduate School of Medicine, Tokushima, Japan; Departments of Bioengineering and Orthopaedics, Engineering Center for Orthopaedic Research Excellence, University of Toledo, Toledo, Ohio, USA.
Departments of Bioengineering and Orthopaedics, Engineering Center for Orthopaedic Research Excellence, University of Toledo, Toledo, Ohio, USA.
World Neurosurg. 2024 Apr;184:e282-e290. doi: 10.1016/j.wneu.2024.01.112. Epub 2024 Jan 26.
To determine the effects of thoracic stiffness on mechanical stress in the lumbar spine during motion.
To evaluate the effect of preoperative thoracic flexibility, stiff and flexible spine models were created by changing the material properties of ligaments and discs in the thoracic spine. Total laminectomy was performed at L4/5 in stiff and flexible models. A biomechanical investigation and finite element analysis were performed preoperatively and postoperatively. A hybrid loading condition was applied, and the range of motion (ROM) at each segment and maximum stress in the discs and pars interarticularis were computed.
In the preoperative model with the stiff thoracic spine, lumbar disc stress, lumbar ROM, and pars interarticularis stress at L5 increased. In contrast, as the thoracic spine became more flexible, lumbar disc stress, lumbar ROM, and pars interarticularis stress at L5 decreased. All L4/5 laminectomy models had increased instability and ROM at L4/5. To evaluate the effect of thoracic flexibility on the lumbar spine, differences between the stiff and flexible thoracic spine were examined: Differences in ROM and intervertebral disc stress at L4/5 in flexion between the stiff and flexible thoracic spine were respectively 0.7° and 0.0179 MPa preoperatively and 1.5° and 0.0367 MPa in the L4/5 laminectomy model.
Biomechanically, disc stress and pars interarticularis stress decrease in the flexible thoracic spine. Flexibility of the thoracic spine reduces lumbar spine loading and could help to prevent stress-related disorders.
确定运动过程中胸腰椎僵硬度对腰椎机械应力的影响。
为了评估术前胸椎柔韧性的影响，通过改变胸椎韧带和椎间盘的材料特性，建立了僵硬和柔韧脊柱模型。在僵硬和柔韧模型中，在 L4/5 进行全椎板切除术。术前和术后进行生物力学研究和有限元分析。应用混合加载条件，计算每个节段的活动范围（ROM）和椎间盘及小关节突的最大应力。
在术前僵硬胸椎模型中，L5 椎间盘应力、腰椎 ROM 和小关节突应力增加。相反，随着胸椎变得更加柔韧，L5 椎间盘应力、腰椎 ROM 和小关节突应力降低。所有 L4/5 椎板切除术模型的 L4/5 不稳定和 ROM 增加。为了评估胸椎柔韧性对腰椎的影响，检查了僵硬和柔韧胸椎之间的差异：僵硬和柔韧胸椎的 L4/5 屈伸 ROM 和椎间盘应力差异分别为术前 0.7°和 0.0179 MPa，以及 L4/5 椎板切除术模型中的 1.5°和 0.0367 MPa。
从生物力学角度来看，柔韧性好的胸腰椎间盘应力和小关节突应力降低。胸椎的柔韧性降低了腰椎的负荷，有助于预防与应力相关的疾病。
