Chitosan-coated Stainless Steel Screws for Fixation in Contaminated Fractures

Abstract

Stainless steel screws and other internal fixation devices are used routinely to stabilize bacteria-contaminated bone fractures from multiple injury mechanisms. In this preliminary study, we hypothesize that a chitosan coating either unloaded or loaded with an antibiotic, gentamicin, could lessen or prevent these devices from becoming an initial nidus for infection. The questions investigated for this hypothesis were: (1) how much of the sterilized coating remains on the screw with simulated functional use; (2) is the unloaded or loaded chitosan coating bacteriostatic and biocompatible; and (3) what amount and rate does an antibiotic elute from the coating? In this study, the gentamicin eluted from the coating at a detectable level during 72 to 96 hours. The coating was retained at the 90% level in simulated bone screw fixation and the unloaded and loaded chitosan coatings had encouraging in vitro biocompatibility with fibroblasts and stem cells and were bacteriostatic against at least one strain of Staphylococcus aureus. The use of an antibiotic-loaded chitosan coating on stainless steel bone screws and internal fixation devices in contaminated bone fracture fixation may be considered after optimization of antibiotic loading and elution and more expanded in vitro and in vivo investigations with other organisms and antibiotics.

Quaternized Chitosan Inhibits icaA Transcription and Biofilm Formation by Staphylococcus on a Titanium Surface

“…These results indicate that precoating of orthopedic implants with HACC has the potential to block bacterial colonization and biofilm formation. Chitosan has been investigated as a potential coating material for the prevention of orthopedic infections (4,16,22). Although it has an improved ability to inhibit biofilm formation, coating of metal implants with HACC is challenging because of its high water solubility.…”

Novel Antibiotic-loaded Point-of-care Implant Coating Inhibits Biofilm

“…Differences in molecular weight and chemical structure may affect retention and release of different antibiotics from phosphatidylcholine. Antibiotics released from coatings were confirmed to be active in inhibiting growth of microorganisms through turbidity and zone of inhibition assays with similar activity to other antimicrobial coatings [5,14,25,43,69]. Although effective in inhibiting bacterial growth and biofilm formation, several of the implant coating strategies have the limitation of requiring prefabrication [25,43] and chemical modification with specific preselected antibiotics [4,29].…”

“…Recent developments have been focused on degradable and customizable local delivery strategies to ensure coverage of the wound, effective antibiotic elution, and minimization of secondary procedures [15,30,60]. These local delivery strategies include degradable sponges [50], injectable biomaterials [48,53,80], and coatings of antimicrobial molecules on implanted surfaces [25,30,43,66]. These materials vary in degradation rate and elution profile of antimicrobials and may require prefabrication to attach antimicrobial molecules or coating materials to implant surfaces.…”

Materials in Fracture Fixation

“…Hydroxyapatite-coated screws show a greater resistance to Staphylococcus epidermidis adherence, 52 and chitosan-coated screws and plates have been shown to be bacteriostatic. 53 Silver, silicon polymer, and silicon or nitrogen doped diamond-like carbon (DLC) coatings on implants have reduced bacterial adhesion to components, and have shown efficacy against strains of Staphylococcus aureus and Staphylococcus epidermidis. [54][55][56] Hydrogel coatings containing the antibiotic ciprofloxacin are being developed to prevent implant-associated infections in titanium devices.…”