The design of additively manufactured lattices to increase the functionality of medical implants

Research output: Contribution to journalArticle

External organisations

  • Cardiff Metropolitan University
  • Queen Elizabeth Hospital Birmingham

Abstract

© 2018 Elsevier B.V. The rise of antibiotic resistant bacterial species is driving the requirement for medical devices that minimise infection risks. Antimicrobial functionality may be achieved by modifying the implant design to incorporate a reservoir that locally releases a therapeutic. For this approach to be successful it is critical that mechanical functionality of the implant is maintained. This study explores the opportunity to exploit the design flexibilities possible using additive manufacturing to develop porous lattices that maximise the volume available for drug loading while maintaining load-bearing capacity of a hip implant. Eight unit cell types were initially investigated and a volume fraction of 30% was identified as the lowest level at which all lattices met the design criteria in ISO 13314. Finite element analysis (FEA) identified three lattice types that exhibited significantly lower displacement (10-fold) compared with other designs; Schwartz primitive, Schwartz primitive pinched and cylinder grid. These lattices were additively manufactured in Ti-6Al-4V using selective laser melting. Each design exceeded the minimum strength requirements for orthopaedic hip implants according to ISO 7206-4. The Schwartz primitive (Pinched) lattice geometry, with 10% volume fill and a cubic unit cell period of 10, allowed the greatest void volume of all lattice designs whilst meeting the fatigue requirements for use in an orthopaedic implant (ISO 7206-4). This paper demonstrates an example of how additive manufacture may be exploited to add additional functionality to medical implants.

Details

Original languageEnglish
Pages (from-to)901-908
Number of pages8
JournalMaterials Science and Engineering C
Volume94
Early online date13 Oct 2018
Publication statusPublished - 1 Jan 2019

Keywords

  • Additive manufacture, Drug delivery, Finite element analysis, Lattice, Mechanical testing, Therapeutics