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Strong, antibacterial surface may solve problems with external fixator pins
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BELFAST, NORTHERN IRELAND — Staphylococcus aureus colonies on titanium external fixation pins were significantly reduced when the pins underwent a surface ceramic conversion process, according to a presenter, here.
At the British Orthopaedic Association Annual Congress, Huan Dong presented the results of a study he and colleagues at Royal Derby Hospital and the University of Birmingham in Birmingham, United Kingdom conducted. They sought to determine whether surface ceramic conversion, a process developed at the University of Birmingham that is a surface treatment rather than a coating, would impart antibacterial and hardness properties to self-drilling titanium pins used in external fixators.
“This is the first time we have used ceramic surface conversion on titanium ex-fix pins. It has shown excellent antimicrobial activity even without [ultraviolet] UV radiation, which is something we could try in the future to improve it further. It has also improved the mechanical properties, which [are] usually decreased for most types of coatings,” Dong said.
The treatment involved applying 600° heat to the pins for 85 hours in a controlled atmosphere, Dong said, which results in a fixed oxide and a hard oxygen layer beneath it on the surface of the pin.
When researchers compared the treated pins to the untreated pins, electron microscopy showed the surface of the treated pins was converted to a titanium oxide layer (~2µ) that was rutile. According to the findings, that layer was “supported by an O2 hardened case (~15µ) with good bonding.”
Dong and colleagues also incubated treated and untreated pins with S. aureus for 20 hours.
“We showed a 50% reduction in the number of S. aureus-forming colonies in the treated pins vs. the untreated pins,” Dong said. This reduction was statistically significant.
Furthermore, not only did the researchers find a three-times greater surface hardness in the treated pins than the untreated pins, Dong said he found it easier to insert the pins during sawbones drilling tests.
“It is a commercially viable, cheap, simple, environmentally friendly treatment with lots of potential for the future,” he said. – by Susan M. Rapp
Reference:
Dong H, et al. Paper #492. Presented at: British Orthopaedic Association Annual Congress; Sept. 13-16, 2016; Belfast, Northern Ireland.
Disclosure: Dong reports no relevant financial disclosures.