Design and 3D-printing of titanium bone implants: brief review of approach and clinical cases

Abstract

Additive manufacturing (AM) is an alternative metal fabrication technology. The outstanding advantage of AM (3D-printing, direct manufacturing), is the ability to form shapes that cannot be formed with any other traditional technology. 3D-printing began as a new method of prototyping in plastics. Nowadays, AM in metals allows to realize not only net-shape geometry, but also high fatigue strength and corrosion resistant parts. This success of AM in metals enables new applications of the technology in important fields, such as production of medical implants. The 3D-printing of medical implants is an extremely rapidly developing application. The success of this development lies in the fact that patient-specific implants can promote patient recovery, as often it is the only alternative to amputation. The production of AM implants provides a relatively fast and effective solution for complex surgical cases. However, there are still numerous challenging open issues in medical 3D-printing. The goal of the current research review is to explain the whole technological and design chain of bio-medical bone implant production from the computed tomography that is performed by the surgeon, to conversion to a computer aided drawing file, to production of implants, including the necessary post-processing procedures and certification. The current work presents examples that were produced by joint work of Polygon Medical Engineering, Russia and by TechMed, the AM Center of Israel Institute of Metals. Polygon provided 3D-planning and 3D-modelling specifically for the implants production. TechMed were in charge of the optimization of models and they manufactured the implants by Electron-Beam Melting (EBM^®), using an Arcam EBM^® A2X machine.

Keywords: 3D-printing; Additive manufacturing; Bio-medical implants; CAD design; Computed tomography; Electron beam melting; Ti–6Al–4V.

Fig. 1

a Photo of the Arcam EBM^® A2X machine used by TechMed. b SEM-image of the Ti–6Al–4V powder provided by Arcam EBM^® (Molndal, Sweden). c SEM-image of the typical microstructure of Ti–6Al–4V alloy

Fig. 2

The process stages of titanium EBM^® implant production

Fig. 3

Example of conversion of CT into a final mandibular implant for a cancer patient case

Fig. 4

Different software packages for bio-medical 3D-modelling and 3D-printing

Fig. 5

a Arcam EBM^® Q-10. b Arcam EBM^® Q-20. c EOS DMLS^® M290. d SLM-500

Fig. 6

a Anatomic design, b manufactured clavicle implant with a lattice structured insert by TechMed Technion: 1—titanium implant polished from the upper side for better interaction with muscles; 2—3D-printed polymer model of the broken clavicular bone; 3—lattice structure part of a titanium implant. Image processing was done using medical R&D software package Mimics by Materialise [6] Courtesy of J. Ramon and G. Muller, TechMed Technion

Fig. 7

a Healthy human hip bone structure. b Proposed by PB-AM lattice structure replacements

Fig. 8

Overview of the anatomic design of the mandibular implant with a lattice structure by TechMed: 1—ABS-model; 2—EBM-manufactured titanium implant with 4 connecting points; 3—the upper click-connection Courtesy of G. Dzhenzhera and E. Strokin

Fig. 9

Left to right: a Anatomic design 3D-planning image. b Titanium bone implants made from Ti–6Al–4V using EBM^® technology. c Implant surgery. Image processing was done using the medical R&D software package by Polygon Medical Engineering [16]

Fig. 10

Left to right: a 3D-model of anatomic design. b Titanium implant with a plastic model. c, d Surgery of titanium hip replacement implant made from Ti–6Al–4V using EBM^® technology. Image processing was done using the medical R&D Software package by Polygon Medical Engineering [16]