Abstract Gradual screw loosening is a well-known failure mechanism in internal fixation. Loosening is primarily due to progressive bone loss caused by stress shielding, a phenomenon in which a medical device absorbs a disproportionate amount of load within the screw-bone construct. The proximity of elastic moduli of magnesium and bone presents the potential for alleviating screw loosening by allowing optimum stress to be transferred between screw and bone, and in turn, supporting bone remodeling around the screw. In this study, the effect of thread profile on stress transfer in a magnesium fixation was simulated using a 2-D finite element model. Modified stress parameters from a previous study were used to estimate stress transfer across three thread profiles. Results showed highest stress transfer in trapezoidal-shaped magnesium screw thread. In accordance, this study corroborates the potential for magnesium as an ultimate screw material to eliminate progressive screw loosening.

中文翻译：

---

螺纹形状对骨骼应力传递的影响：有限元研究

摘要 螺钉逐渐松动是众所周知的内固定失败机制。松动主要是由于应力屏蔽引起的渐进性骨质流失，这种现象是医疗器械在螺钉骨结构内吸收了不成比例的负载。镁和骨骼的弹性模量接近，通过允许在螺钉和骨骼之间传递最佳应力，进而支持螺钉周围的骨骼重塑，从而有可能减轻螺钉松动。在这项研究中，使用二维有限元模型模拟了螺纹牙型对镁固定件中应力传递的影响。先前研究中修改后的应力参数用于估计三个螺纹轮廓之间的应力传递。结果表明梯形镁螺纹中的应力传递最高。