Purdue researchers are developing a biodegradable metal orthopedic implant that could be safely absorbed by the body. Purdue-developed metal pins (left) are absorbed into the body after providing short-term support. Conventional metal pins (right) often must be removed in a second surgery.
(Image provided by Marine Traverson and Gert Breur/Purdue College of Veterinary Medicine)

Originating in 2009 in the lab of Lia Stanciu, a professor of materials engineering at Purdue University, researchers are developing a nontoxic, biodegradable orthopedic implant that could be safely absorbed by the body after giving adequate support to damaged bones – eliminating a second surgery to remove conventional hardware.

“Most implants use stainless steel and titanium alloys for strength. This can cause long-term change in the mechanics of the specific region and eventual long-term deterioration,” Stanciu says.

Secondary surgery to remove the implant or accompanying hardware result in added medical costs and can lead to an increased risk of complications.

Co-inventors of the technology are Stanciu; Eric Nauman, a professor in Purdue’s College of Engineering and director of the College of Engineering Honors Programs; and Ph.D. candidate Michael J Heiden and graduate research assistant Mahdi Dehestani, both in Purdue’s School of Materials Engineering.

Nauman says, “The implant has high porosity in which optimal vascular invasion can occur. This provides a way for cells to optimally absorb the material,” Nauman states. “Our technology is able to provide short-term fixation but eliminate the need for long-term hardware such as titanium or stainless steel.”

The orthopedic implant also uses manganese, which provides a better degradation rate, Stanciu adds.

“Current resorbable metals are made with magnesium; however, this provides many adverse side effects to the body and degrades very quickly,” Stanciu says.

Studies showed that using manganese instead of magnesium could control the degradation rates from 22mm per year to 1.2mm per year pretty consistently. Researchers also saw that manganese has a very good corrosion rate throughout.

Nauman notes the technology still exhibits the usual benefits associated with using biomaterials. “With this technology, we are able to tailor the surfaces such as de-alloying the surface to provide a better material for cells to grab on to and grow. We were also able to show that we could control cell attachment proliferation, an increase of the number of cells. Our technology still has all these usual benefits in addition to controlling the degradation rates of the metals.”

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