Optimisation of composite bone plates for ulnar transverse fractures

N.D Chakladar,L.T Harper,A.J Parsons

doi:10.1016/j.jmbbm.2016.01.029

N.D Chakladar, L.T Harper + Show 1 more

Open Access

https://doi.org/10.1016/j.jmbbm.2016.01.029

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Abstract

Metallic bone plates are commonly used for arm bone fractures where conservative treatment (casts) cannot provide adequate support and compression at the fracture site. These plates, made of stainless steel or titanium alloys, tend to shield stress transfer at the fracture site and delay the bone healing rate. This study investigates the feasibility of adopting advanced composite materials to overcome stress shielding effects by optimising the geometry and mechanical properties of the plate to match more closely to the bone.An ulnar transverse fracture is characterised and finite element techniques are employed to investigate the feasibility of a composite-plated fractured bone construct over a stainless steel equivalent. Numerical models of intact and fractured bones are analysed and the mechanical behaviour is found to agree with experimental data. The mechanical properties are tailored to produce an optimised composite plate, offering a 25% reduction in length and a 70% reduction in mass. The optimised design may help to reduce stress shielding and increase bone healing rates.

Highlights

IntroductionDiaphyseal fractures (transverse to bone shaft) of the ulna are sometimes treated with internal fixations such as bone plate/ screw systems to provide support to the fractured bone and to assist healing
Diaphyseal fractures of the ulna are sometimes treated with internal fixations such as bone plate/ screw systems to provide support to the fractured bone and to assist healing
Titanium (Ti) and stainless steel (SS) alloys are commonly adopted for orthopaedic trauma fixation devices, but stress shielding, reduced callus growth rate and increased risk of second surgery are of concern

Summary

Introduction

Diaphyseal fractures (transverse to bone shaft) of the ulna are sometimes treated with internal fixations such as bone plate/ screw systems to provide support to the fractured bone and to assist healing. These plates are designed to stabilise the fracture and to restrict further damage, by bringing the broken bone ends together and fixing them using neutral and compression screws. This fixation enhances the primary and secondary bone healing rates (Aro and Chao, 1993). Bone resorption (a process where journal of the mechanical behavior of biomedical materials 57 (2016) 334–346 bone breaks down to release its minerals into the blood) sometimes takes place due to a reduction of mechanical stresses around the fracture site, which weakens the integrity of the bone and initiates bone re-fracture (Tonino et al, 1976)

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