Characterisation of the cortical shell and trabecular architecture of the lateral masses of the human cervical spine

8:05 am 29 Aug 2014

Professor Brett Kirk from the School of Civil and Mechanical Engineering at Curtin University and PhD students Matthew Olda kowski and Intan Oldakowska are developing a novel orthopaedic fastener for use in the lateral mass of the cervical spine during spine stabilisation surgery.

The cortical morphology and tra becular architecture of the lateral mass are critical to the design of the fastener, but is not well char acterised. With help from NIF re searcher A/Prof Matt Linden and NIF facility fellow Diana Engineer at the Centre for Microscopy, Characterisation and Analysis at The University of Western Aus tralia the team analyses micro computed to mography scans of cadaveric cervical verte brae for these characteristics and to describe the effect of gender and age.Sheep vertebral bodies are also analysed to determine wheth er they are an appropriate model for testing prototypes.

Finite element analysis is performed on pro spective designs of the novel orthopaedic fas tener using geometry extracted from the CT scans. The prototypes are manufactured by Professor Tim Sercombe from the School of Mechanical and Chemical Engineering at UWA using Selective Laser Melting, a 3D printing process, to allow the manufacture of designs which cannot be manufactured by conven tional means. Fresh frozen sheep vertebrae will be scanned before drilling (to determine sample .

properties), after drilling (to lo cate the fastener in the finite element model and investigate the effect of drilling and awling on trabecular architecture) and after the fastener has been im planted and expanded (to verify the finite element model.)

Initial scans by the Skyscan 1176 Micro CT were at 9 µm resolu tion and 90kV and reconstructed using NRecon. However prelim inary measurements of volume fraction and trabeculae thick ness (see figure 3 & 4) were in sensitive to resolution reduction up to 18 µm and so subsequent scans were taken at this resolu tion to reduce reconstruction time.

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