基于ASTM F543-17标准测试的医用接骨螺钉旋动扭矩计算模型

目的研究医用接骨螺钉的旋动扭矩计算模型。方法分析自攻型接骨螺钉在旋入过程中的3个主要阶段,对螺纹形成阶段的扭矩与扭转角进行力学建模与模拟计算;同时,根据ASTM F543-17(YY/T 1506-2016)标准的要求,对来自3个厂家的规格均为φ2.9×12接骨螺钉在不同等级聚氨酯实验块上开展螺钉体外旋入实验,将实验结果与计算结果进行比较分析。结果理论模型所得与实验测得最大旋入扭矩偏差值分别为5、12 m N·m,小于实验测得扭矩的10%,在可接受的误差范围内。结论所开发的接骨螺钉旋动力学计算模型能够模拟并预测研发与临床应用中的旋动扭矩,结合体外扭动实验,能够为接骨螺钉的研发与设计提供一种有效途径。

Calculation Model for Insertion Torque of Medical Bone Screws Based on ASTM F543-17

Objective To study numerical model for calculating the insertion torque of bone screw. Methods The three stages of screw insertion process for the self-tapping screw were analyzed,so as to make mechanical modeling and simulation calculation on torque and torque angle at screw forming stage. Meanwhile,the insertion experiments of screws with specification of φ 2. 9 × 12 from three manufactures on polyurethane test blocks with different grades were performed according to ASTM F543-17( YY/T 1506-2016),and the experimental results were compared with the calculated ones. Results The deviations between the predicted insertion torque by the model and the measured torque in the experiments were 5 mN·m and 12 mN·m within the acceptable error range,which were 10% smaller than the average measured torque in the experiments. Conclusions The developed mechanical calculation model can be used to simulate and predict the insertion torque of medical bone screws in research and development or clinical use,and its combination with in vitro mechanical experiments provides an effective way of developing and designing bone screws.