Pascoletti Giulia, Cianetti Filippo, Putame Giovanni, Terzini Mara, Zanetti Elisabetta M
Department of Engineering, University of Perugia, Perugia, Italy.
PolitoBIOMed Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy.
Front Bioeng Biotechnol. 2018 Nov 21;6:174. doi: 10.3389/fbioe.2018.00174. eCollection 2018.
The Marchetti-Vicenzi's nail is an intramedullary device where six curved nails are kept straight by a closing ring in order to allow their insertion into the medullary canal of a long bone; in a following step, these nails stabilize the fracture due to the ring withdrawal and to the consequent elastic expansion of the nails. Pre-clinical testing of this sort of device is strongly advocated in order to be able to foresee their stability inside the medullary canal and to quantify their stiffening action on a broken bone. In this numerical work, an MB (Multi Body) model of the device has been developed, with the dual purpose of evaluating forces between the bone and the system components during its progressive opening and verifying the behavior of the stabilized bone when it undergoes external loading. Different solutions, for flexible body modeling (discretization with lumped parameters, "flexible body," "FE Part"), have been analyzed and compared in terms of accuracy of results and required computational resources. Contact parameters have been identified and criteria to simplify geometries and therefore to reduce simulation times have been given. Results have allowed to demonstrate how a moderate lateral force is able to dislocate the fracture and how the final position of the retention nut can be optimized. On the whole, a tool for the pre-clinical testing of elastic intramedullary nails has been given.
马尔凯蒂 - 维琴齐钉是一种髓内装置，其中六根弯曲的钉子通过一个闭合环保持伸直状态，以便将其插入长骨的髓腔；在接下来的步骤中，由于环的退出以及钉子随之产生的弹性扩张，这些钉子可稳定骨折部位。强烈建议对这类装置进行临床前测试，以便能够预测它们在髓腔内的稳定性，并量化它们对骨折骨的加固作用。在这项数值研究中，已开发出该装置的多体（MB）模型，其双重目的是评估装置在逐渐打开过程中骨骼与系统组件之间的力，并验证稳定后的骨骼在承受外部载荷时的行为。针对柔性体建模（集中参数离散化、“柔性体”、“有限元部件”）的不同解决方案，已在结果准确性和所需计算资源方面进行了分析和比较。已确定接触参数，并给出了简化几何形状从而减少模拟时间的标准。结果表明，适度的侧向力如何能够使骨折部位移位，以及如何优化固定螺母的最终位置。总体而言，已提供了一种用于弹性髓内钉临床前测试的工具。
