Institute of Structural Mechanics, University of Rostock, Albert-Einstein-Str. 2, Rostock 18059, Germany.
Biomechanics and Implant Technology Research Laboratory, Department of Orthopaedics, Rostock University Medical Center, Rostock, Germany.
Med Eng Phys. 2023 Sep;119:104032. doi: 10.1016/j.medengphy.2023.104032. Epub 2023 Jul 25.
Due to the increasing number of periprosthetic femoral fractures (PFF), the optimisation of implant design gains importance. For the presented research a validated, subject specific finite element model of a human femur with an inlying total hip stem was used to compare the influence of different geometrical implant parameters on the development of PFF. The heterogeneous bone tissue was modelled on the basis of computed tomography scans. A ductile damage model with element deletion was applied to simulate bone fracture in a load case re-enacting a stumbling scenario. The results were compared in terms of fracture load, subsidence and fracture pattern to analyse the influence of friction at the implant-bone interface, implant size and stem length. The results showed that higher friction coefficients lead to an increase of fracture load. Also, the usage of an oversized implant has a negligible effect while an undersized implant reduces the fracture load by 48.9% for the investigated femur. Lastly, a higher fracture load was reached with an elongated stem, but the bending and change in fracture path indicate a more distal force transmission and subsequent stress shielding in the proximal femur.
由于人工股骨假体周围骨折 (PFF) 的数量不断增加，因此优化植入物设计变得尤为重要。在本次研究中，使用了经过验证的、具有内置全髋关节柄的人体股骨的特定于主体的有限元模型，以比较不同几何植入物参数对 PFF 发展的影响。基于计算机断层扫描对非均匀骨组织进行建模。采用带有单元删除的韧性损伤模型模拟跌倒场景下的骨骨折。根据骨折载荷、下沉和骨折模式进行结果比较，以分析植入物-骨界面摩擦、植入物尺寸和柄长度的影响。结果表明，较高的摩擦系数会导致骨折载荷增加。此外，使用过大的植入物几乎没有影响，而使用过小的植入物会使所研究股骨的骨折载荷降低 48.9%。最后，使用长柄可达到更高的骨折载荷，但弯曲和骨折路径的变化表明，近端股骨中的力传递更靠近远端，随后出现应力屏蔽。
