摩擦磨损是造成人工关节等生物医用材料在体内失效的主要因素.借助生物材料磨损试验机,对生物植入材料进行体外实验,以考察材料的强度、摩擦磨损等性能.这对于生物材料在人体中的应用研究十分重要.介绍一种新型的销盘型(pin on disc,POD)生物植入材料磨损测试装置(Biotribo-POD).该试验机可以对生物材料进行生物摩擦学试验,主要用于模拟和预测临床中人工关节等生物材料的磨损特性,其中对髋关节、膝关节和肩关节植入材料的预测是研究的重点.该试验机有6个工位,可以同时对6个销进行试验.装置分为4个模块:加载模块、销导向模块、框架模块和运动模块.该试验机的主要特点是可以通过电脑程序的控制实现多种轨迹,而且可通过调节所受载荷研究运动情况对材料磨损造成的影响.
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。
A pelvic endoprosthesis is the primary means of pelvic reconstruction after internal hemipelvectomy. In this study, a novel biomimetic hemipelvic prosthesis, including an artificial ilium, an artificial acetabulum, and an artificial pubis, was developed. A Finite Element Method （FEM） was carried out to investigate the biomechanical performance of a pelvis reconstructed with biomimetic hemipelvic prosthesis. Two models, including the reconstructed pelvis and the original pelvis （control model）, were established according to the geometry from CT data of a human male patient with pelvic bone sarcomas. The FE models predict that the biomeehanical function of the pelvic ring can be reestablished using this prosthesis. Results show that the body force loaded on the S 1 vertebra is restored and transferred towards the sacro-iliac joint, and along the ilium onto the bearing surface of the artificial ilium, then to the artificial acetabulum and pubis. Von Mises stresses observed in this reconstructed pelvis model are still within a low and elastic range below the yielding strength of cortical bone and Ti6A14V. The values of deformation and strain of the reconstructed pelvis are close to the data obtained in the original pelvis. With the partial replacement of the pubis, little influence is found towards the pubis symphysis. However, the interface between the prosthesis and pelvic bone may become the critical part of the reconstructed pelvis due to the discontinuity in the material properties, which results in stress shielding and deformation constraining. So a biomimetic flexible connection or inter layer to release the deformation of pelvis is suggested in future designing.
