Customized Hip Implants Fatigue Failure

With an increasing number of joint replacement surgeries worldwide, there is an increased awareness about the use of customized implants instead of standard implants. The number of joint replacement surgeries performed in India is also increasing every year.
Customized hip implant is a hip prosthesis specifically designed for hip anatomy of a particular patient, and manufactured in a single sample. Human activities exert forces, which generate stresses varying with time and results in fatigue failure of the implant material. Therefore, customized hip implants should be checked against fatigue failure. This research work aimed to fatigue testing of custom hip implants with a minimum number of the experiments using Taguchi method for 147 patients. This research is also useful for determining the geometric parameters of influence on the fatigue safety factor of customized hip implants. Taguchi methods and ANOVA were used to find out which geometric parameters are statistically significant for the higher fatigue safety factor of the hip implant. Multiple regression analysis was also performed to replace the FE solver, as well as quickly and accurately
For this purpose, a fatigue testing machine on the basis of a cam and follower mechanism was designed and developed. Fatigue testing was carried out under similar conditions of the ISO 7206-4 fatigue testing. Nine custom hip implants were tested in fatigue tests. The strain gauges are attached to the nine hip implants to derive stress-life curves for the number of cycles applied to hip implants. The results of fatigue tests showed that all hip implants are safe enough in terms of fatigue life. This study shows that the implants satisfy the conditions set by ISO 7206-4. It was concluded that a fatigue testing machine, which is based on a cam and follower mechanism was suitable for fatigue testing of custom-made hip