Abstract:
In fracture fixation, biodegradable implant materials are an interesting alternative to conventional non-biodegradable materials as the latter often require a second implant removal surgery to avoid long-term complications. In this study, we present an in silico strategy to design/study biodegradable metal implants focusing on mandibular fracture fixation plates of WE43 (Mg alloy). The in silico strategy is composed of an orchestrated interaction between three separate computational models. The first model simulates the mass loss of the degradable implant based on the chemistry of Mg biodegradation. A second model estimates the loading on the jaw plate in the physiological environment, incorporating a phenomenological dynamic bone regeneration process. The third model characterizes the mechanical behavior of the jaw plate and the influence of material degradation on the mechanical behavior. A sensitivity analysis was performed on parameters related to choices regarding numerical implementation and parameter dependencies were implemented to guarantee robust and correct results. Different clinical scenarios were tested, related to the amount of screws used to fix the plate. The results showed a lower initial strength when more screw holes were left open, as well as a faster decrease over time in strength due to the increased area available for surface degradation. The obtained degradation results were found to be in accordance with previously reported data of in vivo studies with biodegradable plates. The combination of these three models allows for the design of patient-specific biodegradable fixation implants able to deliver the desired mechanical behavior tuned to the bone regeneration process.
摘要:
在骨折固定术中,生物可降解植入材料是传统非生物可降解材料的一个有趣的替代品,因为后者通常需要第二次植入物移除手术,以避免长期并发症。在这项研究中,我们提出了一种针对WE43(镁合金)下颌骨骨折固定板的可生物降解金属植入物的设计/研究策略。计算机模拟策略由三个独立的计算模型之间的协调交互组成。第一模型模拟基于Mg生物降解的化学性质的可降解植入物的质量损失。第二个模型估计在生理环境下颚板的负荷,结合了现象学的动态骨再生过程。第三个模型表征了颚板的力学行为以及材料降解对力学行为的影响。对与数值实现选择相关的参数进行了敏感性分析,并实现了参数依赖性,以保证结果的鲁棒性和正确性。测试了不同的临床情况,与用于固定板的螺钉数量有关。结果表明,当打开更多的螺孔时,初始强度较低,以及由于可用于表面降解的面积增加,强度随着时间的推移而更快地降低。发现获得的降解结果与先前报道的使用可生物降解板的体内研究数据一致。这三种模型的组合允许设计患者特异性可生物降解的固定植入物,其能够递送调节至骨再生过程的期望的机械行为。