3D Metal Printing Improves Customization for Medical Implants
(Source: Lamina/stock.adobe.com; generated with AI)
Implantable medical devices (IMDs) are vital medical technology that helps many people overcome various ailments, from joint replacement to stents and pacemakers. For many patients, an off-the-shelf component is sometimes the only option due to cost constraints or material availability. In other cases, fabricating customized IMDs can keep patients waiting to receive treatment, often causing prolonged discomfort and potentially exacerbating the condition.
In recent years, 3D metal printing has emerged as a quick way to produce IMDs. In some cases, 3D metal printers can be installed in medical facilities to further speed the process and allow clinicians to have an input into the design process in real time. 3D metal printing can also work with difficult materials, meaning that it can manufacture more robust IMDs and achieve more complex geometries to provide a better fit for the patient.
This blog discusses how 3D metal printing brings design freedom into the medical space, enabling patients to have more biocompatible and properly fitted implants.
Ideal IMDs with 3D Metal Printing
3D printing provides design freedom and material customizability that is unavailable with almost any other manufacturing technique. In medical applications, 3D-printed implants need to be robust, biocompatible, resistant to biofluids and biofouling, and integrate easily into the surrounding tissue (i.e., osseointegration, the ability for the natural bone tissue to grow into the synthetic implant to ensure that the implant functions like its natural counterpart). Generally, metal is a better 3D printing material for IMDs when compared to plastics and ceramics. In many cases, conventional IMDs are made from different metals and metal alloys, so 3D metal printing is essentially a more efficient extension of existing IMD manufacturing methods.
The customization of 3D metal printing gives medical professionals the ability to create specific IMDs with the ideal shape, size, and surface finish for their patients, instead of taking one off the shelf that might not fit properly. Implants that don’t fit properly and cause discomfort may need to be replaced during another surgical procedure, which puts more strain on patients and health care providers. 3D-printed IMDs enable medical professionals to design a more suitable implant for a patient, meaning lower chances that it will need to be replaced.
Some of the more common IMDs starting to use 3D metal printing include:
- Acetabular (hip) cups
- Foot and ankle implants
- Spinal implants and spinal cages
- Stents
- Knee implants
- Shoulder implants
- Bone plates
Benefits of 3D Metal Printing
Two key benefits of 3D metal printing are speed and design customization. In most cases, using 3D metal printing negates the need for extra post-processing steps—such as a hot isostatic press (HIP) or polishing—that are common in traditional manufacturing processes. As a result, the overall manufacturing time (not just the part production itself) can be reduced significantly.
The design freedom and customization abilities of 3D printing enable health care professionals to customize not just the geometry of an IMD, but also the internal properties and surface finish to ensure that it functions optimally and is more biocompatible (and, therefore, longer lasting). 3D printing can also be used with metal alloys that are traditionally difficult to work with, providing access to more robust and stronger alloys that are more comfortable and more resistant to corrosion and degradation. The use of nontraditional IMD alloys must still be approved by regulatory bodies, so many manufacturers consider existing materials that are already used in the IMD space, including cobalt chrome, stainless steel, and the titanium alloy Ti-64.
Because IMDs require different materials and functions based on where (and why) they are placed in the body, the ability to customize the material and functional properties at the microscopic level is a key reason for the increased popularity of 3D metal printing in the medical industry. Scientists can significantly change a material's intrinsic properties by internally changing the level of porosity, fusion, and microstructure. This allows manufacturers to effect macro-level changes in the fundamental properties of the IMD based on the needs of the patients. The surface finish can also be tailored to match the patient's bio-integration, osseointegration, and bio-corrosion resistance requirements.
For example, Ti-64 is a notoriously difficult alloy to work with but has excellent properties that are beneficial for a range of IMDs. By changing the microstructure of these materials through the design process, Ti-64 IMDs can be developed with a stronger, more robust structure that provides greater mechanical strength. Alternatively, the microstructure can be made more sponge-like and softer so that it can expand with the natural movements of the surrounding tissue and organs, such as for artificial spinal cages that need to move to accommodate breathing.
Conclusion
3D metal printing brings design freedom and customization to many high-tech and regulated industries. In the medical space, health care professionals' ability to quickly produce customized implants is enabling more patients to have biocompatible and properly fitting implants. These 3D-printed devices are less likely to degrade over time, which reduces the need for replacement procedures or additional surgeries.