Magnesium & Rare Earths: Valuable Potential in the Medical Implant Field

Highlights

• Researchers from multiple universities investigate magnesium’s potential as a biodegradable implant material, using rare earth elements to improve its mechanical properties and corrosion resistance.
• Rare earth elements like cerium, lanthanum, neodymium, and yttrium can enhance magnesium alloys’ strength, ductility, and biocompatibility for medical applications.
• The study demonstrates promising potential for customized medical implants in orthopedic and cardiovascular treatments that can naturally degrade while supporting healing processes.

---

Researchers at Texas A&M University College Station, Cleveland State University, Oklahoma State University, Stanford University and Indian Institute of Information Technology in Chennai, India review some of the limitations limiting the use of magnesium (Mg) as a candidate for biodegradable implants in biomedicine.  From poor formability and susceptibility to corrosion, the authors investigate Mg’s biodegradation mechanisms and the various degradation modes activated by different physiological environments. With an aim on the optimization of Mg’s utility as a biomaterial, the authors are also directed by the “transformative potential of integrating rare-earth (RE) elements into Mg allows.” So, the authors’ key aim here is to better understand how to materially refine the microstructure, bolster mechanism properties, and harden corrosion resistance, to overcome existing Mg limitations.

The recent study published in Journal of Magnesium & Alloys (opens in a new tab) investigated the mixture of magnesium and key rare earths demonstrates real promise in the field of customizable medical device implants.

What’s rare earth elements have to do with it?

Known as rare earth elements (REEs), the authors of the recent paper point to the aim of markedly improving the mechanical properties of magnesium alloys.

Add cerium and lanthanum, and this forms protective oxide layers, lowering susceptibility to corrosion. Then add neodymium, stopping hydrogen embrittlement; and add yttrium which refines grain size.

Put this combination of REE and develop a “diverse range of properties, including enhanced strength, creep resistance, high-temperature performance, corrosion resistance, ductility, and toughness.”

So, what’s possible with the REE enabled Mg?

More flexible alloy selection for specific applications according to the researchers.  The authors also investigate effects of various RE elements on biodegradability, cytotoxicity, and biological interaction, vital medical applications.

The authors produce prototype implants, based on experimentation with additive manufacturing (AM), part of a series of experiments to develop efficient Mg-RE-based biomedical implants. This output helped the researchers produce the precise customization of implants based on specific patient needs.

What’s the promise here? Based on the researcher’s thorough effort  they report a “future of Mg-RE alloys as groundbreaking biomaterials poised to redefine medical implant technology with their superior mechanical and biological properties.”

Rare Earth Exchanges Summary

Magnesium and rare earth elements are increasingly being explored for use in medical implants due to their unique properties that can benefit patients in orthopedic and cardiovascular applications. Here’s a breakdown of why these materials is promising for medical implants and the benefits they offer.

First and foremost a topic of growing interest per this study is the use of magnesium in medical implants.  As we discussed already some key benefits of magnesium in medical implants:

• Biodegradability: Magnesium is a biodegradable metal, meaning it naturally dissolves in the body over time. This is ideal for implants that do not need to remain permanently, such as temporary bone screws, pins, or plates used in fracture healing.
• Biocompatibility: Magnesium is biocompatible, with minimal toxicity to surrounding tissues. It’s an essential mineral for the body, playing roles in bone health, metabolism, and cell function, so its degradation byproducts are usually well-tolerated.
• Mechanical Properties: Magnesium has mechanical properties like natural bone, such as flexibility and density, which can reduce the risk of “stress shielding.” Stress shielding occurs when a much stiffer metal implant (like titanium) bears the load rather than the bone, weakening it over time.
• Applications: Magnesium implants are mainly used in orthopedic and cardiovascular devices, such as stents, bone screws, and fracture fixation devices. Magnesium-based stents, for instance, can provide temporary vessel support in cardiovascular treatments and then degrade safely after the vessel has healed.

What about mixing REEs in magnesium alloys?

As the study demonstrated taking rare earth elements (such as yttrium, neodymium, and gadolinium) and alloying with magnesium can improve its mechanical strength, corrosion resistance, and biocompatibility. This allows magnesium implants to maintain structural integrity longer before degrading, which is critical for healing.

Other benefits occur with the mixing of the REEs in with Mg including the enhancement of corrosion control and the reduction of inflammatory responses.

Key benefits of mg plus RE implants”

• No secondary surgery
• Support for bone regeneration
• Customized degradation profiles

What are some research and development hurdles that must be overcome?

For controlled corrosion engineers look to discover the right balance in degradation rates as this factor remains a challenge, as corrosion must be predictable to align with thepatient’s healing timeline. Another key point in the field ofmedicine is of course regulatory approval. Given the novelty of these materials, obtaining regulatory approval requires comprehensive biocompatibility and safety studies.

Also, there are economics involved. For example, working with rare earth alloys in medical-grade manufacturing can be costly and technically challenging, so improving manufacturing processes is key to making these implants more accessible.

What are some potential applications in the medical sector?

There could be many but Rare Earth Exchanges shares a few below:

• Orthopedic implants
• Cardiovascular stents
• Soft tissue scaffolds

In conclusion, magnesium and rare earth alloys represent a promising frontier in biocompatible and biodegradable medical implants. With ongoing research, these materials could transform orthopedic, cardiovascular, and regenerative medicine by providing safe, effective, and temporary implant options tailored to support healing and reduce the need for repeat surgeries.  The study reviewed raises important opportunities and challenges, as well as potential solutions involving use of Mg and REEs.