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21

Numerical Assessment of Bone Tissue

Remodeling of a Proximal Femur After Insertion

of a Femoral Implant Using an Interpolating

Meshless Method

†
,‡
,†
M.M.A. Peyroteo* , A.T.A. Castro , Jorge Belinha* ,
Renato M. Natal Jorge †
†
*Institute of Science and Innovation in Mechanical and Industrial Engineering (INEGI), Porto, Portugal Faculty of
‡
Engineering of University of Porto (FEUP), Porto, Portugal School of Engineering Polytechnic of Porto (ISEP),
Porto, Portugal

21.1 INTRODUCTION

Total hip arthroplasty (THA) is considered the “surgery of the century,” being one of the most successful surgical
replacement procedures in orthopedics. In THA the natural hip joint is replaced with an artificial prosthesis, aiming to
restore the joint function and consequently increase the quality of life of the patient. A variety of pathologies can lead to
the necessity for hip joint replacement, being the three main diseases primary osteoarthritis (76%); rheumatoid arthritis
(6%); and conditions that can evolve to fracture (11%), such as osteoporosis [1].
To take on the missing physiological functions, a hip prosthesis must assure three important requirements [2]. The
set of materials constituting the prosthesis must have adequate mechanical properties to withstand millions of charge
cycles without fracturing. Besides this structural requirement, artificial joint must not compromise the movement of
the musculoskeletal system and withstand the corrosive physiological bone environment.
There are two types of arthroplasty: primary arthroplasty and revision arthroplasty. Primary arthroplasty is the
replacement of the natural hip joint with an artificial one. However, when the artificial joint fails, a second surgical
procedure is required. The revision arthroplasty is then the removal of the original implant and the replacement with
a new implant. Revision arthroplasties are often more difficult to perform compared with primary arthroplasties, since
the patient has less bone tissue volume.
In the United States of America, between 2003 and 2013, primary and revision THAs increased up to 174%–130%,
respectively [3]. Moreover a recent study predicted that, by 2030, the number of primary and revision THAs will
increase, causing an increase in costs from $8.43 billion in 2003 to $22.7 billion in 2030 [4]. The aging of the population
and the reduced useful lifetime of the prosthesis components are some of the factors that explain these statistics [2].
Although the use of implants has helped many patients to restore their joint function, complications can occur, since
integration of a foreign body into a highly corrosive physiological environment can be exceptionally challenging. There-
fore an early revision arthroplasty is required when some factors such as infection, displacement, stress shielding, or asep-
tic loosening occur [5, 6]. Implant failure due to stress shielding is explained by a severe bone resorption and consequently
weakening of bone as a result of decreased physiological loading of the bone. The release of debris from wear of the pros-
thesis materials is the main cause of aseptic loosening. This process induces again bone resorption and, subsequently,
detachment of the implant. The main outcomes of implant failure are fracture or total displacement of the implant.

Advances in Biomechanics and Tissue Regeneration 405 © 2019 Elsevier Inc. All rights reserved.
https://doi.org/10.1016/B978-0-12-816390-0.00021-2