Orthopaedic implant coating helps to ward off infection

Better knee and hip replacements are one step closer, with Australian and Chinese researchers having developed a new orthopaedic implant coating that has the strong ability to ward off infection as well as to stimulate bone growth. Their patented technology, which has been described in the journal Advanced Functional Materials, consists of novel silver–gallium (Ag–Ga) nano-amalgamated particles that can be easily applied to medical device surfaces.

Infections after orthopaedic implant surgery are a global health issue, with rates ranging from 2–10% in developed countries and up to 15% in developing regions. About 6% of orthopaedic implant infections lead to intensive care, with a mortality rate up to 4.6%; the cost of treating such infections can exceed US$100,000 per case.

“The antibacterial capabilities of compounds derived from silver have been extensively researched,” said corresponding author Dr Vi-Khanh Truong, from the Biomedical Nanoengineering Laboratory (BNL) at Flinders University. “However, the cytotoxicity of silver ions currently poses a significant obstacle for the utilisation of silver ions in medical materials.

“Our new formula involving Ag–Ga nano-amalgamation ensures the sustained release of silver and gallium ions in a very controlled manner to eliminate these issues.”

Gallium liquid metal (GaLM) was used to facilitate the galvanic deposition of silver nanocrystals on an oxide layer. The GaLM not only serves as a carrier for silver through the galvanic replacement process but also provides a controlled-release mechanism for silver.

The Ag–Ga nano-amalgamated particles were found to exhibit potent antimicrobial properties against a broad spectrum of bacterial strains in animal models. Senior author Matthew Flinders Professor Krasimir Vasilev, Director of the BNL, said the breakthrough provides an urgently needed solution to medical device-associated infections.

“The new material could be easily and controllably applied by spray-casting on many medical devices to protect them against infection, and also provide anti-inflammatory effect and stimulate bone growth,” he said.

“Our latest testing indicates this combination of antibacterial protection and tissue integration properties can benefit many devices in the orthopaedic, trauma and also dental areas.”

Truong added that the discovery has the potential to apply to various implantable devices, catheters and other access devices, and even wound dressings where infections are also problematic. “Commercialisation opportunities could make this solution available to clinicians and patients in the near future — at a time when growing antibiotic resistance is yet another problem in global health care,” he said.

Image credit: iStock.com/libre de droit