Development of Hip Implant: Gait Study and Finite Element Analysis

The hip joint gives stability to the whole human structure making it an important part of the human body that provides the ability to carry out various everyday work such as walking and running. Although hip joint replacement is commonly and successfully performed, an increased number of younger and active patients widens the range of motion of patients leading to the need for a longer lifetime of the replacement joint. This matter puts a challenge to the orthopedic surgical procedures that is needed to be overcome. This paper studies the effect of gait activity and loading acting across the joint by using Finite Element Analysis (FEA) to evaluate the total deformation and von Mises stress distribution of the hip implant. Alongside, structural analysis is conducted to evaluate a better implant design that has less stress distribution which is lesser than its yielded strength to avoid implant failure. FEA was performed using Computer-Aided Engineering (CAE) software of ANSYS by static structural analysis to study the mechanical behaviors of 3-dimensional hip implant models with the femoral design being loaded with forces ranging from 2.5 to 6.4 kN. Obtained results show von Mises stress distribution ranging from 400-1000 MPa of different gait activities, most cases are notably lower than the yield stress value of titanium alloy, Ti-6Al-4V (860 MPa). This work revealed the critical stress concentration located on the hip implant by numerical analysis with lesser stress values than the yielded strength that offers to improve optimization of implant design and life expectancy to avoid the hip implant revision in active patients.

I. Introduction

The process of replacing a diseased hip joint with an artificial part called prostheses where it replicates the hip joint is known as a total hip replacement (THR). The necessity of a hip joint replacement is based on the damage to the hip joint caused by breaking or cracking of the joint. When a fracture occurs in the joint, the femoral head will no longer be securely intact in the acetabulum. Consequently, the motion of the hip will deteriorate resulting in depletion of the hip joint [1]–[3]. The usual cause of hip fracture is due to sudden shock acting on the joint [4].