• Gill, H. S.
• Macleod, Alisdair
• Taylor, Ryan
• Casonato, Alberto

Abstract

Objectives<br/>Additive manufacturing has led to numerous innovations in orthopaedic surgery: surgical guides; surface coatings/textures; and custom implants. Most contemporary implants are made from titanium alloy (Ti-6Al-4V). Despite being widely available industrially and clinically, there is little published information on the performance of this 3D printed material for orthopaedic devices with respect to regulatory approval. <br/>The aim of this study was to document the mechanical, chemical and biological properties of selective laser sintering (SLS) manufactured specimens following medical device (TOKA®, 3D Metal Printing LTD, UK) submission and review by the UK Medicines and Healthcare Products Regulatory Agency (MHRA).<br/>Methods <br/>All specimens were additively manufactured in Ti-6Al-4V ELI (Renishaw plc, UK). Mechanical tests were performed according to ISO 6892-1, ISO 9585 and ISO 12107 for tensile (n=10), bending (n=3) and fatigue (n=16) respectively (University of Bath, UK). Appropriate chemical characterisation and biological tests were selected according to recommendations in ISO 10993 and conducted by external laboratories (Wickham Labs, UK; Lucideon, UK; Edwards Analytical, UK) in adherence with Good Lab Practise guidelines. A toxicological review was conducted on the findings (Bibra, UK).<br/>Results <br/>The mechanical tests demonstrated that the material performed to the specification for conventionally manufactured titanium alloy of this type (ISO 5832-3). The toxicology review concluded that there were no significant concerns for the health of the patients identified in this evaluation and implantation of the TOKA® device would not result in a significant health risk to patients.<br/>Conclusions<br/>Reflecting on our MHRA experience, additive manufacture of orthopaedic devices is still considered to be a ‘novel’ process by regulatory bodies, requiring additional safety evidence. Despite this, our findings demonstrate that there is no difference, mechanically or chemically, to the traditionally manufactured alloy material. We hope to support the widening use of 3D printed titanium alloy orthopaedic devices by publishing our route to regulatory approval.<br/>

Topics

• impedance spectroscopy
• surface
• strength
• fatigue
• texture
• titanium
• titanium alloy
• tensile strength
• sintering
• laser sintering
• biocompatibility
• static light scattering