Tensi H M, Gese H, Ascherl R
Proc Inst Mech Eng H. 1989;203(4):215-22. doi: 10.1243/PIME_PROC_1989_203_042_01.
In this finite element study the stresses between a stem component of a cementless hip endoprosthesis (Young modulus of Co-Cr-Mo) and the human femur were calculated for two different loading types. Linear and non-linear models were used to simulate the interface implant bone. Two models, a stem with a porous coated surface over the entire length and a stem with a porous coated surface in the proximal region were compared regarding the load transmission to the femur. An additional calculation of an 'isoelastic' stem (Young modulus of cortical bone) was done to show the influence of the stem stiffness. A porous coated surface over the entire length causes principal shear stresses up to 2.75 MPa in the distal-medial region during level walking. The highest compressive stresses were calculated in the proximal-lateral region as 1.5 MPa in cancellous bone. A more physiological load transmission is obtained by limiting the coated area to the proximal region. All stresses in the two models are lower than experimentally evaluated strengths in the interface between implant and bone. A strong influence of the Young modulus of the stem material on the interface stresses was found. An 'isoelastic' stem causes compressive stresses in the proximal-lateral region whose values exceed the experimental strength of cancellous bone.
在这项有限元研究中，针对两种不同的加载类型，计算了无骨水泥型髋关节假体的柄部件（钴铬钼合金的杨氏模量）与人体股骨之间的应力。使用线性和非线性模型来模拟植入物与骨的界面。比较了两种模型，一种是在整个长度上具有多孔涂层表面的柄，另一种是在近端区域具有多孔涂层表面的柄，以研究它们向股骨的载荷传递情况。还对一个“等弹性”柄（皮质骨的杨氏模量）进行了额外计算，以显示柄刚度的影响。在平步行走时，整个长度上具有多孔涂层表面会在远侧内侧区域产生高达2.75兆帕的主剪应力。在松质骨中，近端外侧区域计算出的最高压应力为1.5兆帕。通过将涂层区域限制在近端区域可获得更符合生理的载荷传递。两种模型中的所有应力均低于植入物与骨界面的实验评估强度。发现柄材料的杨氏模量对界面应力有很大影响。一个“等弹性”柄在近端外侧区域产生的压应力值超过了松质骨的实验强度。
