A combined finite element method and continuum damage mechanics approach to simulate the in vitro fatigue behavior of human cortical bone

The fatigue of bone, in particular the associated modulus degradation and a ccumulation of permanent strain, has been implicated as the cause of femora l neck fractures and the migration of total joint replacements. The objecti ve of this study was to develop a technique to simulate the tensile fatigue behavior of human cortical bone. A combined continuum damage mechanics (CD M) and finite element analysis (FEA) approach was used to predict the numbe r of cycles to failure, modulus degradation and accumulation of permanent s train of human cortical bone specimens. The simulation of fatigue testing o f eight dumb-bell specimens of cortical bone were performed and the predict ions compared with existing experimental data. The predictions from the fin ite element models were in close agreement with the experimental data. The models predicted similar development of modulus degradation and permanent s train as observed in the experimental tests. The technique is capable of pr edicting the accumulation of permanent strain without the need for simulati ng every single load step. These findings suggest that the complex fatigue behavior of human cortical bone can be simulated using the described approa ch and forms the first step for simulating the more complex mechanisms asso ciated with femoral neck fractures and implant migration. (C) 1999 Kluwer A cademic Publishers.