In this paper, the finite element method is used to analyse the crack behaviour in the orthopedic cement of the total hip replacement by computing the stress intensity factors (SIFs) arround the crack tip. In this work, three cases are studied: crack emanating from a cavity, interaction effect of the crack emanating from a cavity with another cavity and the interaction effect of two cracks emanatingfrom two cavities. The stress intensity factors under mixed mode problems at the crack tip are computed for three zones of prosthesis: proximal, median and distal. The obtained results show that the crack initiated from a micro-cavity in the distal zone of cement can be propagated at the same time by opening and shearing of its lips. It is contrary to that initiated in the proximal zone which cannot be propagated. The mechanical behaviour of cracks in the medial zone depends of the crack initiation position.

Modelling of a crack propagating through a finite element mesh under mixed mode conditions is of prime importance in fracture mechanics. In this paper, three different crack growth criteria and the respective crack paths prediction in the cement mantle of the reconstructed acetabulum are compared. The maximum tangential stress (MTS) criterion, the minimum strain energy density (MSED) criterion and the new general fracture criterion based on the energy release rate G(θ) are investigated using advanced finite element technique. The displacement extrapolation technique (DET) is used, to obtain the SIFs at crack tip. Several examples are presented to show the robustness of the numerical techniques. The effect of the inclusions and cavities on the crack propagation in cement orthopedic are highlighted.

An explicit analysis conducted on the crack behavior in chirurgical cement (Polymethylmethacrylate -PMMA) used for Total Hip Prosthesis (THP) is of great importance in collecting information about the nature of the phenomenon of loosening of the cement application. The rupture of the orthopedic cement is practically the main cause of this loosening. Understanding different rupture mechanisms give a great value in advancing the durability of the cemented total prosthesis. The purpose of this study is to analyse cracks behavior, initiated in the cement that links the femoral-stem with the bone, using the Finite Element Analysis Method (FEM). The present study brings into focus the variation of the stress intensity factor in modes I, II and III. This rupture criterion is used according to the nature of crack, its orientation and its location in the orthopedic cement. At first, the level and distribution of the equivalent von Mises stress is analysed, which is induced in the medial, proximal and distal parts of the bone cement. Then, the behavior of different geometric forms of an elliptical crack is evaluated which are located and initiated within the body of these three parts.

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Cement is the weakest link in the composition of total hip prosthesis in terms of mechanical properties. The knowledge of the intensity and distribution of stresses on the cement attaching the implant to the bone is of great importance for understanding the condition of the prosthesis and its failure. In this study, the finite element method is used to analyze the magnitude and the equivalent Von Mises stress distribution induced in different components of the total hip prosthesis (THP) as well as the identification of the damage induced in the cement and between two cavities located in the polymethyl methacrylate (PMMA). The crack propagation is determined and localized using the extended element method (XFEM). The results show that the fracture stress of the cement in its proximal part is very important. These stresses increase considerably with the interaction of the cavities in this binder, causing damage to the cement and the loosening of the prosthesis.