Antimicrobial Effect of Silver-Coated External Fixator Pins

Abstract

One major complication of external fixation is pin track infection that may result in devastating osteomyelitis for the patient. The broad antimicrobial effect of silver is well known and this study was conducted to investigate the antibacterial activity of pins coated with colloidal silver. A total of 96 pins were inserted into one tibia of 24 sheep. Four pins of either stainless steel, titanium, silver-coated, or stainless steel pins coated with a polyurethane-argentum sleeve were inserted in six sheep, respectively. After pin insertion S. aureus was inoculated into the insertion channel between skin and bone and the animals were sacrificed after four weeks. Clinical assessment, radiological evaluation, microbiological and biomechanical testing, and histological methods were used. All animals developed clinical signs of infection after three to six days. The inoculated S. aureus was identified in all animals as an infection-causing strain by the DNA-fingerprinting technique. None of the different pin types, including silver-coated pins, showed a significant reduction of infection rates. Significant differences between the groups were rare and limited to few specific tests. Colloidal silver showed no significant reduction of pin track infections. Nanoparticulate silver with a higher active surface and a more homogenous distribution within biomaterials might be able to exhibit a better antimicrobial activity in coated pins.