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RESEARCH ARTICLE

3D Topology Optimization and Mesh Dependency for

Redesigning Locking Compression Plates Aiming to

Reduce Stress Shielding

A. A. Al-Tamimi*

Industrial Engineering Department, College of Engineering, King Saud University, Riyadh 11421 Saudi Arabia

Abstract: Current fixation plates for bone fracture treatments are built with biocompatible metallic materials such as stainless
steel, titanium, and its alloys (e.g., Ti6Al4V). The stiffness mismatch between the metallic material of the plate and the host
bone leads to stress shielding phenomena, bone loss, and healing deficiency. This paper explores the use of three dimensional
topology-optimization, based on compliance (i.e., strain energy) minimization, reshaping the design domain of three locking
compression plates (four-screw holes, six-screw holes, and eight-screw holes), considering different volume reductions (25,
45, and 75%) and loading conditions (bending, compression, torsion, and combined loads). A finite-element study was also
conducted to measure the stiffness of each optimized plate. Thirty-six designs were obtained. Results showed that for a critical
value of volume reductions, which depend on the load condition and number of screws, it is possible to obtain designs with
lower stiffness, thereby reducing the risk of stress shielding.
Keywords: Bone plates; Finite element analysis; Mesh dependency; Stress shielding; Topology optimization.

*Correspondence to: Abdulsalam Al-Tamimi, Industrial Engineering Department, College of Engineering, King Saud University,
Riyadh 11421 Saudi Arabia; aaaltamimi@ksu.edu.sa
Received: January 5, 2021; Accepted: June 30, 2021; Published Online: July 1, 2021

Citation: Al-Tamimi AA., 2021, 3D Topology Optimization and Mesh Dependency for Redesigning Locking Compression
Plates Aiming to Reduce Stress Shielding. Int J Bioprint. 7(3):339.http://doi.org/10.18063/ijb.v7i3.339

1. Introduction design consisting of a conventional screwing system and a
Locking Head Screw system . LCP allows a gap between
[6]
Bone fractures represent a critical healthcare problem. In the bone and the implant to achieve callus formation and
USA, number of fracture cases is predicted to increase is more suitable for osteoporotic fractures .
[6]
from 2.1 million in 2005 to around three million in Internal fixations (e.g., plates and screws) are built
2025 . Bone fixation implants are considered one of the using biocompatible metallic materials such as stainless
[1]
riskiest implants , as the UK’s National Health Service steel (i.e., 316L) and titanium-based alloys (e.g., Ti-6Al-
[2]
(NHS) reported over 11,000 revision operations for failed 4V). Such metallic materials present Young’s modulus
implants in 2016 . of around 120 GPa for Ti-6Al-4V and 190 GPa for 316L
[3]
Fractures are often surgically treated with bone stainless steel, significantly higher than that for cortical bone
fixation devices such as internal fixators, external fixators, (around 20 GPa) [7-9] . This large difference is one of the main
and intramedullary pins . Internal fixations, the focus of causes of the stress shielding phenomenon characterized
[4]
this research, are usually applied to fixate the fractured by the lack of mechanical stimulation of the bone through
bone through restoring the bone segments into its original disruption of load distribution across in the bone-plate
functionality and anatomy. Since the introduction of the construct. This phenomenon affects the bone remodeling
first metallic internal fixations in 1895 by Lane, different process, causing implant loosening and bone loss.
designs were developed and introduced in the market . Different methods have been explored to reduce
[5]
At present, the Locking Compression Plate (LCP) is the stress shielding effect through the change of built
the most commonly used fixation plate due to its hybrid material (e.g., functionally graded materials) and/or design

© 2021 Al-Tamimi. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons. org/
licenses/by/4.0/), permitting distribution and reproduction in any medium, provided the original work is cited.
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