Customized hip implant is a hip prosthesis specially developed for hip anatomy of a particular patient and manufactured in a single sample. Human activities exerted forces, which generate stresses that vary over time and resulting in fatigue failure of the hip implant. Therefore, customized hip implant should be checked against fatigue failure. The aim of this work was to develop a new experimental model for in vitro custom hip implants fatigue testing with minimum number of experiment by using Taguchi method for 147 patients. To this end, a fatigue testing machine was developed, based on a cam and follower mechanism. This machine is able to apply the hip contact force in typical physiological load conditions; including normal walking and walking up and down the stairs. Nine custom hip implants were developed by using Taguchi L9 orthogonal array for fatigue tests. Fatigue testing was carried out under similar conditions of the ISO 7206-4 fatigue testing. The results of fatigue tests showed that all hip implants are safe enough in terms of fatigue life. The nine hip implants have been tested for 1, 80,000 cycles and until then no failure has occurred in the hip implant. The strain recorded by the strain recording software shows that the fatigue life of experiment no. 8 hip implant is more as compared to experiment no. 5 hip implant. This study also shows that the Taguchi method is useful for fatigue testing of customized hip implant with a minimum number of experiments.
Keywords : Fatigue Testing, Orthogonal Array, Taguchi, ISO 7206-4, Hip Implant.