Micro-scale surface-patterning influences biofilm formation

The formation of biofilms on indwelling/implanted medical devices is a common problem. One of the approaches used to prevent biofilm formation on medical devices is to inhibit bacterial attachment by modification of the synthetic polymers used to fabricate the device. In this work, we assessed how micro-scale features (patterns) imprinted onto the surface of silicone elastomer similar to that used for medical applications influenced biofilm formation by Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa. Patterns were transferred from a multi-patterned oxidized silicon-wafer master-template to silicone elastomer. Features consisted of bars, squares, and circles each extending 0.51 µm above the surface. Feature sizes ranged between 1.78 and 22.25 µm. Distances separating features ranged between 0.26 and 17.35 µm. Bacterial biofilm formation on discs cut from imprinted silicone elastomer was assessed by direct microscopic observation and quantified as the surface area covered by biofilm. Unpatterned silicone elastomer served as a control. Several of the micro-scale patterns imprinted into the silicone elastomer significantly reduced biofilm formation by each bacterium and interrupted biofilm continuity. Although there were differences in detail among strains, bacteria tended to attach in the area between features more than to the surface of the feature itself.

Isolation and quantitation of debris particles around failed silicone orthopedic implants.

Silicone elastomer implants have a relatively low rate of complications, but inflammatory reactions to debris have been reported. To characterize the size and number of debris particles, we isolated and quantified the debris particles present in the periarticular tissues of 10 patients with failed silicone wrist, elbow, or finger implants. Five rheumatoid synovia without implants were used for negative controls. The number of particles ranged from 0.99 to 24.8 x 10(9) per gram (dry weight) of tissue, and nearly all particles were silicone, as determined by x-ray spectroscopy. The implantation duration ranged from 3.2 to 10.6 years, and for the five wrist implants, the number of particles correlated with duration in vivo. The particles were small (mode particle diameter was 0.59 +/- 0.057 micron). These results suggest that billions of particles, most of which are smaller than 1 micron, are present adjacent to failed silicone implants, and may be associated with inflammation and bone resorption.

Silicone elastomer microshards in fluid from a painful metatarsophalangeal implant site. A case report.

Histopathologic studies have demonstrated microshards from silicone elastomer metatarsophalangeal joint implants in adjacent tissues in a setting of chronic inflammation and in inguinal lymph nodes. Cytologic smears of synovial fluid from symptomatic implanted joints should show these refractile, nonpolarizing microshards in the reactive inflammatory context. Nonspecific enzymatic inflammatory activity contributes to further destabilization of the implants, eventuating in symptoms and signs requiring prosthesis removal. Cytopathologic examination of aspirated fluid from the vicinity of a symptomatic implanted joint demonstrates foreign body reaction to silicone elastomer, predicting a need for intervention before the local damage is severe and disabling.