Reducing stress shielding and weight as well as helping to revascularization of the femur by applying honeycomb holes in hip prosthesis

Abstract

Total hip Arthroplasty is one of the most common surgeries in elderly people around the world. In spite of many successful cases, a few failures are still reported, a significant number of which relates to the effects of stress shielding. Many scientists have been working on solving this problem by enhancing the material and/or the geometry of the hip prostheses' stems. For example, hollow-stemmed hip prostheses have been designed and tested. In this study, 30 hollow-stemmed samples were designed which were different in terms of geometry and dimension of their holes as well as the materials defined for them. Then, they were tested through finite element modeling along with validating and verifying the results using experimental and convergence tests. The results including displacements, maximum stress values and consequent safety factors were compared based on the reactions of the samples against various static loads including the loads predefined by ISO 7206-4 as well as the loads which had been previously obtained. D2 designs show the least stiffness compared to other designs. Designs with 132.66mm2 hole area are the most promising layouts for reducing weight and providing the most amount of medullary space for revascularization of the femur. In spite of designs which predictably help revascularization more than D2 designs, these designs which are of the multi-hole patterns seemed to represent the best outcomes in terms of preventing stress shielding and consequently the best pattern for creating holes in the stem according to the precedence of stress shielding over other problems. The results prove the possibility of representing a promising structure which helps to reduce the weight, stress shielding and the lack of revascularization of the femur. © 2019 World Scientific Publishing Company.