Titanium Implants – How they are Made

Titanium is a commonly used metal for the development of surgical implants, given its distinctive properties, such as the excellent strength and reduced weight. Today, most of the titanium-based surgical implants are created with the help of 3D printing technologies, being used for a wide range of medical problems. Titanium is strong and durable, these being two of its most important characteristics. Moreover, it is non-toxic and biocompatible, being easily accepted by the body (no risk of implant rejection).

When it comes to orthopedic implants, titanium alloys are preferred, these being made with tantalum. 3D printing technology was used by the researchers at the Singapore Institute of Manufacturing Technology; in collaboration with the Singapore Center for 3D Printing, these have managed to create orthopedic implants, using the titanium – tantalum powder. These implants can be customized to each and every patient, guaranteeing a superior absorption of physical stress and shocks (in comparison to other materials commonly used for orthopedic implants, such as ceramics).

The combination of titanium and tantalum is particularly exciting, as it guarantees an increased biocompatibility rate. Moreover, its mechanical properties are superior to the ones of titanium. However, it has been demonstrated that tantalum does not respond well to modern technologies, such as SLM (selective laser melting). In order to produce customized orthopedic implants, researchers had to find a solution to this problem; they resorted to the innovative alloy of titanium and tantalum, creating 3D orthopedic implants with the help of selective laser melting.

The 3D printing technology has also been used for the development of titanium spinal implants. The main idea was to create an implant that would mimic the lamellar structure of the real bone, promoting bone growth and integration at the same time. As with the orthopedic implants, the spinal implants were created with the help of 3D printing technologies, researchers using titanium powder as main element. The laser beam delivered a high level of energy to the titanium powder, thus leading to the formation of spinal implants that follow the lamellar structure of the real bone to the letter. These innovative spinal implants could not have been created with previous technologies, such as casting.

Cranial implants have been developed with the help of 3D printing, using titanium as primary element. These have been approved by the FDA, being also presented as cranio-facial titanium plate implants. The interesting thing about these implants is that they have been developed based on information provided by imaging investigations (MRI, CT scans). In this way, it was possible to develop customized implants, for each and every patient. The implants were created using 3D printing technology, more specifically, electron beam melting (EBM). Thanks to this particular technology, it was possible to create implants that meet the precise requirements of patients who suffer from different cranial/cranio-facial defects. Titanium powder alloys are highly resistant and easily accepted by the body, guaranteeing a faster recovery from the implantation procedure.

Cast titanium implants can be used in patients with cranial defects, as they offer the best possible reconstruction results. These are customized and created with the help of CAD (computer aid design) and/or CAM (computer aided manufacturing). The reconstruction of bony skull defects has become possible with the help of titanium implants; the customization is made facile, thanks to the patients undergoing computer tomography and the collected data being used for the actual implants (3D spiral computer tomography).
Rapid prototyping has replaced the conventional milling procedure, where the implants were practically milled from a block of titanium. This method is advanced and it allows for excellent casting. It can be used to develop a structure similar to the one of the real bone; it allows for complex geometrical forms to be created, with diameters that are quite small.

Researchers have also resorted to 3D fiber deposition, in order to create metallic scaffolds for orthopedic and spinal implants. This technique allows for a number of factors to be controlled, including the size of the pores and level of porosity. The titanium alloy scaffolds are especially useful for spinal implants, demonstrating that metals are and will probably be, for a long period of time, the most suitable choice for surgical implants.

Titanium is preferred for orthopedic implants as well, such as in the situation of hip replacement. This is because it has an excellent load-bearing capacity, allowing the patient to maintain his/her functionality on a long-term basis. Other orthopedic applications have benefitted from the usage of titanium and titanium alloys, most commonly 3D printing technologies being employed for their development. Titanium has mechanical strength to offer, as well as resilience, these being important reasons for why it is preferred to other conventional materials. Its mechanical properties and biocompatibility have also made it suitable for dental implants and device development.

Rapid prototyping is a technique based on fused deposition modeling (3D printing technology). The development of titanium scaffolds for spinal and orthopedic implants is particularly innovative, given the high-accuracy of the designed structure and the ability to promote bone formation.

3D fiber deposition is a manufacturing technique often used for the development of titanium implants (layer-by-layer technique). Using this particular printing technology, researchers have managed to create innovative titanium prototypes. The interesting thing is that one can create layers with different characteristics (fiber diameter, fiber space, fiber orientation, thickness etc.). These can vary from one layer to the other, guaranteeing, as a final result, a titanium implant that has a porous structure, similar to the real bone.

It is clear that the titanium scaffolds created with the help of the 3D fiber deposition can make quite the difference in the field of spinal implants. Thanks to this technology, researchers are able to work with different pore sizes, establishing various porosity levels and customizing the interconnecting pore size at the same time. By controlling the spatial arrangement and the overall architecture, more efficient spinal implants can be created, with excellent osteoconductive properties. Thus, bone growth into the porous titanium alloy implant will appear as a natural consequence, allowing the patient to recover faster from the subsequent medical condition.

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