Influence of functionally graded pores on bone ingrowth in cementless hip prosthesis: a finite element study using mechano-regulatory algorithm

Abstract

Cementless hip prostheses with porous outer coating are commonly used to repair the proximally damaged femurs. It has been demonstrated that stability of prosthesis is also highly dependent on the bone ingrowth into the porous texture. Bone ingrowth is influenced by the mechanical environment produced in the callus. In this study, bone ingrowth into the porous structure was predicted by using a mechano-regulatory model. Homogenously distributed pores (200 and 800 [Formula: see text]m in diameter) and functionally graded pores along the length of the prosthesis were introduced as a porous coating. Bone ingrowth was simulated using 25 and 12 [Formula: see text]m micromovements. Load control simulations were carried out instead of traditionally used displacement control. Spatial and temporal distributions of tissues were predicted in all cases. Functionally graded pore decreasing models gave the most homogenous bone distribution, the highest bone ingrowth (98%) with highest average Young's modulus of all tissue phenotypes approximately 4.1 GPa. Besides this, the volume of the initial callus increased to 8.33% in functionally graded pores as compared to the 200 [Formula: see text]m pore size models which increased the bone volume. These findings indicate that functionally graded porous surface promote bone ingrowth efficiently which can be considered to design of surface texture of hip prosthesis.

A novel design, analysis and 3D printing of Ti-6Al-4V alloy bio-inspired porous femoral stem

“…This higher stiffnesses of cementless dense Ti-6Al-4V alloy stems cause several complications such as poor bone ingrowth, stress shielding, risk of bone fracture, and even revision of surgery. Finite element models are used successfully to investigate the biomechanical behavior of tissues and implants [5][6][7][8][9][10][11][12][13][14][15]. Many published works have used finite element models of implants made of composites and porous biomaterials to overcome the aforementioned complications [16][17][18][19][20].…”

Finite element study of functionally graded porous femoral stems incorporating body‐centered cubic structure

“…Porous stems can reduce femur stress shielding by merely adjusting and controlling the porosity, so their properties match the surrounding femur . Porous stems are also promising because biological fixation of the stem within the femur bone can be attained by virtue of bone ingrowth . The advancement of additive manufacturing techniques, such as selective laser melting (SLM), electron beam melting (EBM), and laser engineering net shaping (LENS), has enabled the design and testing of different porous biomedical implants .…”

“…3,4 The stems are usually made of biocompatible materials such as Ti alloy, cobalt chromium (CoCr) alloy, or carbon-fiber-reinforced polyether ether ketone (CFR-PEEK) composite. 5,6 The mismatch between the stiffness of the dense stem (100-240 GPa) and the femur bone (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) results in the stem carrying most of the body weight, thus leading to aseptic loosening, shielding the femur bone from stresses, and bone resorption. 3,5 Stems of different geometrical designs have been proposed to overcome the issue of stress shielding.…”

“…20 Porous stems are also promising because biological fixation of the stem within the femur bone can be attained by virtue of bone ingrowth. 20,21 The advancement of additive manufacturing techniques, such as selective laser melting (SLM), electron beam melting (EBM), and laser engineering net shaping (LENS), has enabled the design and testing of different porous biomedical implants. 22,23 Simoneau et al 24 have proposed and tested a new design of a porous hip implants to achieve a 47% reduction in flexural stiffness.…”

Femoral Stems With Porous Lattice Structures: A Review

“…The ossification process of callus is a complex process affected by the mechanical environment ( Isaksson et al, 2006 ). Some studies have proposed mechano-regulation algorithms using different mechanical stimuli, such as strain, pore pressure, and fluid velocity, as biological stimulation signals to describe this process ( Huiskes, 1997 ; Isaksson et al, 2006 ; Andreykiv et al, 2008 ; Tarlochan et al, 2017 ). Among them, the mechano-regulation theory based on deviatoric strain (DS) proposed by Isaksson et al ( Isaksson et al, 2006 ) is widely used to predict the osseointegration process at the bone-stem interface ( Mehboob et al, 2017 ; Mehboob et al, 2020a ).…”