Speaking at Medtec Europe in Stuttgart this week, Thomas Ebel, from german materials research centre Helmholtz-Zentrum Geesthacht, examined the progress being made in developing magnesium alloys for biodegradable implants.
Implants
Magnesium, which is already an essential element of the body, is thought to induce bone formation, Ebel said.
In fact the material has been used for implants since 1900. However the problem historically is that during its degradation process, it releases hydrogen, which can cause complications for the patient, as a result of high ion concentrations building up in the body.
"Basically the problem is you get very promsing results but you do get unexpected effects in individual patients."
"This is why alloy development and processing development is our challenge," he added.
The centre offers services including production of the alloy, extrusion of the material, shaping, and finally surface treatment (if necessary).
Less conventionally, the centre has started working in the field of powder metallurgy. Ebel and his colleague are experimenting with combining metal materials with polymeric binders. This allows them to use methods like injection moulding or 3D printing to form and shape the implants and other components. The last stage is to remove the polymeric binder, and finally sinter the part.
Using the sintering method means that the porosity of the alloy is adjustable. This can be particularly useful for applications which require drug-loading, Ebel said.
"Fundamental research in materials and biology is crucial. But testing has to be part of the development. Always remember the combination of alloy compoistion and the processing method is crucial. That is what defines the final properties of the implant. There are many studies you have to do to develop magnesium implants."
"The question is, are biodegradable implants ready for therapy? We would say yes, however there are limited applications at the moment."
Ebel concluded that while a basic understanding of interaction between the material and the biology is still lacking in the industry, the potential for future treatment is very high.