Effect of geometric parameters in the design of customized hip implants.

In this paper, the effects of geometric parameters on the development of stress in custom cementless hip implant have been studied. Taguchi methods and analysis of variance (ANOVA) were used to find out which geometric parameters are statistically significant for the maximum von Mises stresses in the hip implant. The multiple regression analysis was also performed, to replace the FE solver and accurately and quickly predict the stress values for new patients. Three parameters horizontal offset (HO), vertical offset and neck shaft angle (NSA), with three levels have been selected. Based on L9 orthogonal array, nine hip implant shapes with three different geometric parameters were modelled. Stress analysis was carried out by using finite element analysis. ANOVA results showed that HO has the maximum impact on von Mises stresses followed by the NSA. It is shown that as the HO increases, the stress at the given region increases, however, as the neck shaft (NSA) increases the stress at the given region decreases. Good agreement is found between von Mises stresses, calculated from multiple regression analysis and obtained from FE analysis. To redesign customised hip implant for the minimum stresses, the results of this work will be important.