Abstract：
BACKGROUND: Total talar replacement is normally stable and satisfactory. We studied a rational scaffold talus model for each size range created through topology optimization (TO) and comparatively evaluated a topologically optimized scaffold bone talus model using a finite element analysis (FEA). We hypothesized that the rational scaffold would be more effective for application to the actual model than the topologically optimized scaffold.
METHODS: Size specification for the rational model was performed via TO and inner scaffold simplification. The load condition for worst-case selection reflected the peak point according to the ground reaction force tendency, and the load directions \"plantar 10°\" (P10), \"dorsi 5°\" (D5), and \"dorsi 10°\" (D10) were applied to select worst-case scenarios among the P10, D5, and D10 positions (total nine ranges) of respective size specifications. FEA was performed on each representative specification-standard model, reflecting a load of 5340 N. Among the small bone models selected as the worst-case, an arbitrary size was selected, and the validity of the standard model was evaluated. The standard model was applied to the rational structure during validity evaluation, and the TO model reflecting the internal structure derived by the TO of the arbitrary model was implemented.
RESULTS: In worst-case selection, the highest peak von Mises stress (PVMS) was calculated from the minimum D5 model (532.11 MPa). Thereafter, FEA revealed peak von Mises stress levels of 218.01 MPa and 565.35 MPa in the rational and topologically optimized models, respectively, confirming that the rational model yielded lower peak von Mises stress. The weight of the minimum model was reduced from 1106 g to 965.4 g after weight reduction through rational scaffold application.
CONCLUSIONS: The rational inner-scaffold-design method is safer than topologically optimized scaffold design, and three types of rational scaffold, according to each size range, confirmed that all sizes of the talus within the anatomical dimension could be covered, which was a valid result in the total talar replacement design. Accordingly, we conclude that an implant design meeting the clinical design requirements, including patient customization, weight reduction, and mechanical stability, should be possible by applying a rational inner scaffold without performing TO design. The scaffold model weight was lower than that of the solid model, and the safety was also verified through FEA.
METHODS: Size specification for the rational model was performed via TO and inner scaffold simplification. The load condition for worst-case selection reflected the peak point according to the ground reaction force tendency, and the load directions \"plantar 10°\" (P10), \"dorsi 5°\" (D5), and \"dorsi 10°\" (D10) were applied to select worst-case scenarios among the P10, D5, and D10 positions (total nine ranges) of respective size specifications. FEA was performed on each representative specification-standard model, reflecting a load of 5340 N. Among the small bone models selected as the worst-case, an arbitrary size was selected, and the validity of the standard model was evaluated. The standard model was applied to the rational structure during validity evaluation, and the TO model reflecting the internal structure derived by the TO of the arbitrary model was implemented.
RESULTS: In worst-case selection, the highest peak von Mises stress (PVMS) was calculated from the minimum D5 model (532.11 MPa). Thereafter, FEA revealed peak von Mises stress levels of 218.01 MPa and 565.35 MPa in the rational and topologically optimized models, respectively, confirming that the rational model yielded lower peak von Mises stress. The weight of the minimum model was reduced from 1106 g to 965.4 g after weight reduction through rational scaffold application.
CONCLUSIONS: The rational inner-scaffold-design method is safer than topologically optimized scaffold design, and three types of rational scaffold, according to each size range, confirmed that all sizes of the talus within the anatomical dimension could be covered, which was a valid result in the total talar replacement design. Accordingly, we conclude that an implant design meeting the clinical design requirements, including patient customization, weight reduction, and mechanical stability, should be possible by applying a rational inner scaffold without performing TO design. The scaffold model weight was lower than that of the solid model, and the safety was also verified through FEA.
摘要：
背景：距骨置换通常是稳定且令人满意的。我们研究了通过拓扑优化（TO）创建的每个尺寸范围的合理支架距骨模型，并使用有限元分析（FEA）对拓扑优化的支架距骨模型进行了比较评估。我们假设合理的支架比拓扑优化的支架更有效地应用于实际模型。
方法：通过TO和内部支架简化进行合理模型的尺寸规范。最坏情况选择的载荷条件根据地面反作用力趋势反映了峰值点，和载荷方向“足底10°”(P10)，“dorsi5°”（D5），和“dorsi10°”（D10）用于在各自尺寸规格的P10，D5和D10位置（总共9个范围）中选择最坏的情况。对每个代表性规格标准模型进行了有限元分析，反映5340N的负荷。在被选为最坏情况的小骨模型中，选择了任意大小，并对标准模型的有效性进行了评价。将标准模型应用于有效性评估过程中的合理结构，并实现了反映由任意模型的TO导出的内部结构的TO模型。
结果：在最坏情况选择中，从最小D5模型（532.11MPa）计算出最高的vonMises应力（PVMS）。此后,FEA揭示了合理和拓扑优化模型中的峰值vonMises应力水平为218.01MPa和565.35MPa，分别,证实了理性模型产生了较低的峰值冯·米塞斯应力。通过合理的支架应用减轻重量后，最小模型的重量从1106g减少到965.4g。
结论：合理的内部支架设计方法比拓扑优化的支架设计更安全，和三种类型的合理的脚手架，根据每个尺寸范围，确认解剖尺寸内的所有尺寸的距骨都可以被覆盖，这在全距骨置换设计中是一个有效的结果。因此，我们得出的结论是，符合临床设计要求的植入物设计，包括患者定制，减轻体重,和机械稳定性，应该可以通过应用合理的内部支架而不进行TO设计。支架模型重量低于实体模型，安全性也通过FEA进行了验证。
方法：通过TO和内部支架简化进行合理模型的尺寸规范。最坏情况选择的载荷条件根据地面反作用力趋势反映了峰值点，和载荷方向“足底10°”(P10)，“dorsi5°”（D5），和“dorsi10°”（D10）用于在各自尺寸规格的P10，D5和D10位置（总共9个范围）中选择最坏的情况。对每个代表性规格标准模型进行了有限元分析，反映5340N的负荷。在被选为最坏情况的小骨模型中，选择了任意大小，并对标准模型的有效性进行了评价。将标准模型应用于有效性评估过程中的合理结构，并实现了反映由任意模型的TO导出的内部结构的TO模型。
结果：在最坏情况选择中，从最小D5模型（532.11MPa）计算出最高的vonMises应力（PVMS）。此后,FEA揭示了合理和拓扑优化模型中的峰值vonMises应力水平为218.01MPa和565.35MPa，分别,证实了理性模型产生了较低的峰值冯·米塞斯应力。通过合理的支架应用减轻重量后，最小模型的重量从1106g减少到965.4g。
结论：合理的内部支架设计方法比拓扑优化的支架设计更安全，和三种类型的合理的脚手架，根据每个尺寸范围，确认解剖尺寸内的所有尺寸的距骨都可以被覆盖，这在全距骨置换设计中是一个有效的结果。因此，我们得出的结论是，符合临床设计要求的植入物设计，包括患者定制，减轻体重,和机械稳定性，应该可以通过应用合理的内部支架而不进行TO设计。支架模型重量低于实体模型，安全性也通过FEA进行了验证。
