To avoid such complications one may propose to use a less stiff material with mechanical properties close to that of bone. This paper presents an optimal design procedure of the FRC using finite element method. A modularized algorithm of stress analysis FEM in connection with optimization code was adopted. In F1 cases smoothing the interface stresses was achieved, however, in F2 cases the match between stresses in pre and post implantation was accomplished. To pass the local minimums initial values were found using parametric studies.
Table indicates the results of two runs for cemented implants compared with metallic implants.
The results of this study demonstrate the important role of the stem stiffness as a major potential factor in design optimization of orthopaedic implants. In addition, these results show that it is possible to design a flexible FRC that generates realistic stress patterns in bone and consequently increases the chance for maintaining a normal bone morphology. Design contradictions in terms of the risk of resorption and bone loss versus excessive interface stresses remain as a major issue. It is found that a flexible FRC does reduce the bone loss but producing relatively high interface stresses could result in interface debonding. Using an FRC with strong interface bond can reduce the stiffness mismatch and eliminate the risk of debonding.