Cavazzoni Giulia, Pasini Margherita, Le Maitre Christine L, Dall'Ara Enrico, Palanca Marco
Department of Industrial Engineering, Alma Mater Studiorum - University of Bologna, Via Terracini 28, 40131 Bologna, Italy.
Division of Clinical Medicine, School of Medicine and Population Health, The University of Sheffield, Barber House, 387 Glossop Road, Sheffield S10 2HQ, UK; Insigneo Institute, The University of Sheffield, The Pam Liversidge Building, Sheffield S1 3JD, UK.
Acta Biomater. 2025 Mar 1;194:258-269. doi: 10.1016/j.actbio.2025.01.018. Epub 2025 Jan 10.
Intervertebral disc (IVD) degeneration is suspected to affect the distribution of stress and strain near the vertebral endplates and in the underlying bone. This scenario is worsened by the presence of metastatic lesions on the vertebrae (primarily thoracic vertebrae (60-80 %)) which increase the risk of fracture. As such, this study aimed to evaluate the effect of IVD degeneration on the internal volumetric strains and failure modes of human metastatic vertebral bodies. Five human thoracic spinal segments including one vertebra with lytic metastases and one radiologically healthy vertebra (control) were in situ tested in pure compression within a μCT scanner (isotropic voxel size = 39μm). Each specimen was tested in the elastic regime before and after inducing mock IVD degeneration (enzymatic degeneration with collagenase); and at failure after IVD degeneration. The volumetric strain field was measured using a global Digital Volume Correlation approach (BoneDVC). After IVD degeneration, larger maximum (+187 %, P = 0.002, 95 % CI= [-4447, -1209]) and minimum (+174 %, P = 0.002, 95% CI= [1679, 4258]) principal strains were observed in both metastatic and control vertebrae, with peak differences in correspondence of the IVD anulus fibrosus. IVD degeneration caused a transversal fracture pattern in the vertebrae with failure location onset in the middle portion of the vertebral body and in the cortical shell. In conclusion, IVD degeneration was found to be a key factor in determining the failure mode, suggesting the clinical relevance of including IVD level of degeneration to assess patients' risk of spinal instability. STATEMENT OF SIGNIFICANCE: Vertebrae can be affected by pathologies, like bone metastases, while intervertebral discs tend to degenerate during life. Generally, these structures and pathologies are studied separately. In this study, we explored the effects of artificial intervertebral disc degeneration on the mineralised tissues of the vertebrae with metastases. We observed that the induced intervertebral disc degeneration changes the mechanical behaviour of the vertebral trabecular bone. We believe that the findings of this study may influence the scientific community to develop new clinical tools for the prediction of the risk of fracture in vertebrae with spinal metastases, including the degeneration of the intervertebral discs as a parameter.
椎间盘（IVD）退变被怀疑会影响椎体终板附近及下方骨骼的应力和应变分布。椎体上存在转移瘤（主要是胸椎，占60 - 80%）会使这种情况恶化，增加骨折风险。因此，本研究旨在评估IVD退变对人类转移性椎体内部体积应变和失效模式的影响。在μCT扫描仪（各向同性体素大小 = 39μm）内对五个人类胸椎节段进行原位纯压缩测试，其中包括一个有溶骨性转移瘤的椎体和一个影像学上健康的椎体（对照）。每个标本在模拟IVD退变（用胶原酶进行酶解退变）前后的弹性阶段进行测试；并在IVD退变后直至失效时进行测试。使用全局数字体积相关方法（BoneDVC）测量体积应变场。IVD退变后，在转移性椎体和对照椎体中均观察到更大的最大主应变（增加187%，P = 0.002，95%置信区间 = [-4447, -1209]）和最小主应变（增加174%，P = 0.002，95%置信区间 = [1679, 4258]），在椎间盘纤维环对应处存在峰值差异。IVD退变导致椎体出现横向骨折模式，失效位置起始于椎体中部和皮质壳。总之，发现IVD退变是决定失效模式的关键因素，这表明纳入IVD退变程度以评估患者脊柱不稳定风险具有临床相关性。重要性声明：椎体可能受到诸如骨转移等病理情况的影响，而椎间盘在生命过程中往往会退变。一般来说，这些结构和病理情况是分开研究的。在本研究中，我们探讨了人工椎间盘退变对有转移瘤椎体矿化组织的影响。我们观察到诱导的椎间盘退变改变了椎体小梁骨的力学行为。我们认为本研究结果可能会影响科学界开发新的临床工具，用于预测有脊柱转移瘤椎体的骨折风险，包括将椎间盘退变作为一个参数。
