Using three-dimensional rapid prototyping in the design and development of orthopaedic screws in standardised pull-out tests

Laura Jane Leslie, Ashley Connolly, John G Swadener, Sarah Junaid, Kanthan Theivendran, Subodh C Deshmukh

Research output: Contribution to journalArticle

Abstract

The majority of orthopaedic screws are designed, tested and manufactured by existing orthopaedics companies and are predominantly developed with healthy bone in mind. The timescales and costs involved in the development of a new screw design, for example, for osteoporotic bone, are high. In this study, standard wood screws were used to analyse the concept of using three-dimensional printing, or rapid prototyping, as a viable stage of development in the design of a new bone screw. Six wood screws were reverse engineered and printed in polymeric material using stereolithography. Three of the designs were also printed in Ti6Al4V using direct metal laser sintering; however, these were not of sufficient quality to test further. Both the original metal screws (metal) and polymeric rapid prototyping screws were then tested using standard pull-out tests from low-density polyurethane blocks (Sawbones). Results showed the highest pull-out strengths for screws with the longest thread length and the smallest inner diameter. Of the six screw designs tested, five showed no more than a 17% variance between the metal and rapid prototyping results. A similar pattern of results was shown between the screw designs for both the metal and rapid prototyping screws in five of the six cases. While not producing fully comparable pull-out results to orthopaedic screws, the results from this study do provide evidence of the potential usefulness and cost-effectiveness of rapid prototyping in the early stages of design and testing of orthopaedic screws.
Original languageEnglish
Pages (from-to)565-572
JournalProceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine
Volume232
Issue number6
Early online date11 May 2018
DOIs
Publication statusE-pub ahead of print - 11 May 2018

Bibliographical note

© 2018 Sage Publications Ltd. All rights reserved. It is available at: https://doi.org/10.1177/0954411918774359

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