Affiliations: Biomedical Engineering & Sciences Department, School of Mechanical and Manufacturing Engineering, National University of Sciences and Technology, Islamabad, Pakistan
Correspondence:
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Corresponding author: Murtaza Najabat Ali, Biomedical Engineering & Sciences Department, School of Mechanical and Manufacturing Engineering (SMME), National University of Sciences and Technology (NUST), Sector H-12, Islamabad, Pakistan. Tel.: +92 9085 6053; E-mail:drmurtaza@smme.nust.edu.pk
Abstract:
INTRODUCTION: Injuries cover about 11% of World's Disease Burden
depicting fractures to be the leading severe consequence of trauma. Fractures
occur due to force impact or osteoporosis. Fracture healing is a complicated
process. Fracture fixation techniques focus on imparting reduction to fractured
fragments and induce healing. When considering possible fixation methods, the
aspect of micro-movement is an important one, as this induces callus formation which
tends to be a crucial step for fracture healing. Internal fixation of long
bone fractures using metallic plates has been carried out since decades and
recently advancements have been in synthesizing biodegradable plates as
well. The purpose of this research was to fabricate an Auxetic Polymeric
Bone Plate that can be used as an internal fixator for long bone fracture;
this bone plate renders micro-movement due to its counter intuitive
behavior, has the potential to reduce the effect of stress shielding and
allow the same range of motion as that of natural bone.
METHODS: Polyurethane was chosen as a material for the fabrication
of the Auxetic device because of its biocompatibility and non-toxic effects.
The plate was then tested for mechanical properties such as Tensile and
Compression testing to determine the strength.
RESULTS AND DISCUSSION: The tensile testing of the Auxetic polyurethane
specimens showed that the mean of the Poisson's ratio of the samples lies between
-0.68 and -0.87 at different uni-axial tensile load values. The Auxetic
structure of our device has the potential to allow for efficient fixation
because its negative Poisson's ratio offers micro-movement, thereby causing
fixation with relative stability rather than absolute stability. The Auxetic
bone plate can be superior to contemporary plate fixation systems, as it
demands meaningfully small contact points. The suitable mechanical
properties might lessen stress shielding effects that are normally caused by
rigid bone plates. The Auxetic nature of the bone will help align and
sustain the bone fragments with small fracture gaps in order to impart
appropriate assembly to accomplish bone healing.
Keywords: Bone plate, internal fixation, bone fracture, rigid fixation, auxetic, polymeric
