School of Engineering, Monash University Malaysia, Jalan Lagoon Selatan, 46150, Bandar Sunway, Selangor, Malaysia.
Department of Mechanical Engineering, SRM University, Kattankulathur, Tamil Nadu, 603203, India.
Med Biol Eng Comput. 2019 Oct;57(10):2305-2318. doi: 10.1007/s11517-019-02026-6. Epub 2019 Aug 23.
Degenerative disc disease (DDD) is a common condition in elderly population that can be painful and can significantly affect individual's quality of life. Diagnosis of DDD allows prompt corrective actions but it is challenging due to the absence of any symptoms at early stages. In studying disc degeneration, measurement of the range of motion (RoM) and loads acting on the spine are crucial factors. However, direct measurement of RoM involves increased instrumentation and risk. In this paper, an innovative method is proposed for calculating RoM, emphasizing repeatability and reliability by considering the posterior thickness of the spine. This is achieved by offsetting the position of markers in relation to the actual vertebral loci. Three geometrically identical finite element models of L3-L4 are developed from a CT scan with different types of elements, and thereafter, mesh element-related metrics are provided for the assessment of the quality of models. The model with the best mesh quality is used for further analysis, where RoM are within ranges as reported in literature and in vivo experiment results. Various kinds of stresses acting on individual components including facet joints are analysed for normal and abnormal loading conditions. The results showed that the stresses in abnormal load conditions for all components including cortical (76.67 MPa), cancellous (69.18 MPa), annulus (6.30 MPa) and nucleus (0.343 MPa) are significantly greater as compared to normal loads (49.96 MPa, 44.2 MPa, 4.28 MPa and 0.23 MPa respectively). However, stress levels for both conditions are within safe limits (167-215 MPa for cortical, 46 MPa for the annulus and 3 MPa for facets). The results obtained could be used as a baseline motion and stresses of healthy subjects based on their respective lifestyles, which could benefit clinicians to suggest corrective actions for those affected by DDD.
退行性椎间盘疾病（DDD）是老年人群中的一种常见疾病，可引起疼痛，并显著影响个体的生活质量。DDD 的诊断可以及时采取纠正措施，但由于早期没有任何症状，因此具有挑战性。在研究椎间盘退变时，测量运动范围（RoM）和脊柱上的负荷是至关重要的因素。然而，RoM 的直接测量需要增加仪器设备并增加风险。本文提出了一种计算 RoM 的创新方法，通过考虑脊柱的后厚度，强调了重复性和可靠性。这是通过相对于实际椎骨位置偏移标记的位置来实现的。从 CT 扫描中开发了三个具有不同类型元素的 L3-L4 几何上相同的有限元模型，此后，提供了网格元素相关指标来评估模型的质量。使用具有最佳网格质量的模型进行进一步分析，其中 RoM 在文献和体内实验结果中报告的范围内。分析了包括关节突关节在内的各个组件在正常和异常加载条件下的各种类型的应力。结果表明，与正常负载（49.96 MPa、44.2 MPa、4.28 MPa 和 0.23 MPa）相比，所有组件（包括皮质（76.67 MPa）、松质骨（69.18 MPa）、环（6.30 MPa）和核（0.343 MPa））在异常负载条件下的应力显著更大。然而，两种情况下的应力水平均在安全范围内（皮质为 167-215 MPa，环为 46 MPa，关节突为 3 MPa）。基于各自的生活方式，获得的结果可作为健康受试者的基本运动和应力，这可能使临床医生受益，为那些受 DDD 影响的人提供纠正措施建议。
