Additive manufacturing for use in orthopaedics – Imperial College London

DateOct 2016 - Sep 2020
Linkimperial.ac.uk

x10 magnification of a titanium alloy printed structure on a scanning electron microscope, with porous hip implant render

Comparison of titanium alloy and stainless steel failure modes in compression

Use of direct image correlation (DIC) to visualise magnitude and direction of strain across specimen

New additive manufacturing techniques allow for ever finer control of complex structures. These structures have novel material properties that can be tuned for specific mechanical performance1.

Orthopaedic implants can benefit from this new manufacturing design space. Current implants use standard CNC or subtractive methods which use cast or extruded bulk metal. This can be many times stiffer than the bone it will be replacing. By using porous lattices in implant design, the stiffness of components can be controlled and matched to the surrounding tissue, as well as improve bone ingrowth2.

My thesis in this field was titled “Design and testing of additively manufactured lattice structures for musculoskeletal applications“, and is available to download under a CC BY-NC-ND 4.0 Creative Commons license. The aim of this PhD was to investigate the mechanical behaviour of AM lattices, and maximise the clinical benefits of AM for musculoskeletal applications.

I undertook my PhD studentship with the Biomechanics Group at Imperial College London, in collaboration with Renishaw plc, supervised by Professor Jonathan Jeffers.

Presented at leading industry & academic conference
Presented at ISTA 2018, in the 3D Printed Implants and PSI seminar. Presentation title: Investigation of Architectural and Mechanical Anisotropy in Additively Manufactured Structures With Comparison to Bone 
Two first author publications
  1. Hossain, U., Ghouse, S., Nai, K. and Jeffers, J.R., 2021. Controlling and testing anisotropy in additively manufactured stochastic structuresAdditive Manufacturing39, p.101849.
  2. Hossain, U., Ghouse, S., Nai, K. and Jeffers, J., 2021. Mechanical and morphological properties of additively manufactured SS316L and Ti6Al4V micro-struts as a function of build angleAdditive Manufacturing, p.102050.
Patent application based on research findings
Patent pending on a novel lattice structure generation method, which can improve the mechanical isotropy of stochastic lattice structures. 
  1. Wang, X., Xu, S., Zhou, S., Xu, W., Leary, M., Choong, P., Qian, M., Brandt, M. and Xie, Y.M., 2016. Topological design and additive manufacturing of porous metals for bone scaffolds and orthopaedic implants: A review. Biomaterials83, pp.127-141.
  2. Heinl, P., Müller, L., Körner, C., Singer, R.F. and Müller, F.A., 2008. Cellular Ti–6Al–4V structures with interconnected macro porosity for bone implants fabricated by selective electron beam melting. Acta biomaterialia4(5), pp.1536-1544.