Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA; Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA.
Department of Biomedical Engineering and Chemical Engineering, University of Texas at San Antonio, San Antonio, TX, USA.
Comput Biol Med. 2021 Jun;133:104395. doi: 10.1016/j.compbiomed.2021.104395. Epub 2021 Apr 19.
Pathologic vertebral fractures due to metastasis can occur under normal physiologic activities, leading to pain and neurologic deficit. Prophylactic vertebroplasty is a technique used to augment vertebral strength and reduce the risk of fracture. Currently, no technique is available to objectively assess vertebral fracture risk in metastatically-involved vertebral bodies. The aim of the current study was to develop an image-based computational technique to estimate fracture force outcomes during bending. To this end, mechanical testing was performed on intact, simulated defect, PMMA-augmented, and PPF-augmented 3-level spine segments from both sexes under a compression/flexion-type loading condition. The augmentation performance of poly(methyl methacrylate) (PMMA) and poly(propylene fumarate) (PPF) were also evaluated and compared. Cylindrical defects were created in 3-level spine segments with attached posterior elements and ligaments. Using CT images of each segment, a rigidity analysis technique was developed and used for predicting fracture forces during bending. On average, PPF strengthened the segments by about 630 N, resulting in fracture forces similar to those observed in the intact and PMMA-augmented groups. Female spines fractured at about 1150 N smaller force than did male spines. Rigidity analysis, along with age, explained 66% variability in experimental outcomes. This number increased to 74% when vertebral size and age were added to the rigidity analysis as explanatory variables. Both PPF and PMMA similarly increased fracture strength to the level of intact specimens. The results suggest that PPF can be a suitable candidate for augmentation purposes and rigidity analysis can be a promising predicting tool for vertebral fracture forces.
病理性转移导致的椎体骨折可在正常生理活动下发生，导致疼痛和神经功能缺损。预防性椎体成形术是一种用于增强椎体强度和降低骨折风险的技术。目前，尚无技术可用于客观评估转移性受累椎体的骨折风险。本研究的目的是开发一种基于图像的计算技术，以估计弯曲过程中的骨折力结果。为此，在压缩/弯曲加载条件下，对来自两性的完整、模拟缺陷、PMMA 增强和 PPF 增强的 3 级脊柱段进行了机械测试。还评估和比较了聚甲基丙烯酸甲酯 (PMMA) 和聚（丙烯富马酸酯）(PPF) 的增强性能。在带有附着的后元素和韧带的 3 级脊柱段中创建了圆柱形缺陷。使用每个节段的 CT 图像，开发了一种刚性分析技术，并用于预测弯曲过程中的骨折力。平均而言，PPF 将节段强度提高了约 630N，导致的骨折力与完整和 PMMA 增强组观察到的相似。女性脊柱的断裂力比男性脊柱小约 1150N。刚性分析以及年龄解释了实验结果的 66%可变性。当将椎体大小和年龄添加到刚性分析作为解释变量时，这个数字增加到 74%。PPF 和 PMMA 均以与完整标本相同的方式增加了骨折强度。结果表明，PPF 可以作为增强的合适候选物，并且刚性分析可以作为预测椎体骨折力的有前途的工具。
