SAN DIEGO – Rough materials used for orthopedic implants, such as cobalt chromium and titanium, increased bacterial adherence, while smoother materials such as stainless steel did not, results from an image analysis demonstrated.
“In light of these results, it is important to question why we utilize the types of materials we use for various orthopedic procedures,” Dioscaris R. Garcia, Ph.D., said in an interview in advance of the annual Interscience Conference on Antimicrobial Agents and Chemotherapy. “There was no one-size-fits-all material to minimize adherence per the findings of this study, but the findings may suggest that having a smoother surface may minimize the ability of bacterial pathogens to adhere to the surface.”
He characterized the topic of bacterial adherence to orthopedic implants as “an issue of great interest due to how little is known about the biological implications of the materials utilized. The most researched of these materials is titanium, which is touted for its biocompatibility. This study aims to provide a base and a glimpse into how the most commonly utilized orthopedic-relevant materials interact with some of the most commonly encountered pathogens.”
For the study, Dr. Garcia, a molecular pharmacologist at Rhode Island Hospital in Providence, Dr. Alan H. Daniels, an orthopedic surgeon at the hospital, and their associates used scanning electron microscopy and confocal laser scanning microscopy to evaluate the adherence pattern, density, and propagation of six commonly encountered bacterial pathogens (methicillin-sensitive Staphylococcus aureus, methicillin-resistant S. aureus, coagulase-negative Staphylococcus epidermidis, multidrug-resistant Acinetobacter baumannii, Propionibacterium acnes, and vancomycin-resistant Enterococcus faecalis) on five commonly used spinal implant materials (titanium, titanium alloy, stainless steel, cobalt chromium, and polyetherether ketone). The samples were fixed and dehydrated via ethanol dehydration gradient and critical point drying.
The researchers found that some pathogens, such as vancomycin-resistant E. faecalis and multidrug-resistant A. baumannii, were more likely to adhere to more textured materials such as cobalt chromium and titanium, compared with smoother materials such as stainless steel. “Additionally, the findings suggest that the microtopography of these materials may be the driving force behind the adherence of pathogens on the materials themselves,” Dr. Garcia said. Compared with smoother, polished materials, he explained, the rougher materials were more likely to harbor dense proliferation of bacterial pathogens, which could be characterized as biofilms.
“This study has been successful in providing a platform for future studies to build upon and expand to study additional parameters and statistical tools to give further insight into additional driving forces behind adherence and means for improvement of material design,” Dr. Garcia concluded.
Dr. Christopher T. Born, head of the Diane N. Weiss Center for Orthopedic Trauma Research at Rhode Island Hospital, was the study’s principal investigator. The study was supported by Stryker Corp.*
*Correction, 9/19/2015: Dr. Born is a consultant for Stryker. He also has stock ownership in Biointraface, does consulting for the company, and is a member of its board.