Effect on infection resistance of a local antiseptic and antibiotic coating on osteosynthesis implants: An in vitro and in vivo study

Abstract

The purpose of this study was to acquire information about the effect of an antibacterial and biodegradable poly-L-lactide ( PLLA) coated titanium plate osteosynthesis on local infection resistance. For our in vitro and in vivo experiments, we used six-hole AO DC minifragment titanium plates. The implants were coated with biodegradable, semiamorphous PLLA (coating about 30 mm thick). This acted as a carrier substance to which either antibiotics or antiseptics were added. The antibiotic we applied was a combination of Rifampicin and fusidic acid; the antiseptic was a combination of Octenidin and Irgasan. This produced the following groups: Group I: six-hole AO DC minifragment titanium plate without PLLA; Group II: six-hole AO DC minifragment titanium plate with PLLA without antibiotics/antiseptics; Group III: six-hole AO DC minifragment titanium plate with PLLA þ 3% Rifampicin and 7% fusidic acid; Group IV: six-hole AO DC minifragment titanium plate with PLLA þ 2% Octenidin and 8% Irgasan. In vitro, we investigated the degradation and the release of the PLLA coating over a period of 6 weeks, the bactericidal efficacy of antibiotics/ antiseptics after their release from the coating and the bacterial adhesion of Staphylococcus aureus to the implants. In vivo, we compared the infection rates in white New Zealand rabbits after titanium plate osteosynthesis of the tibia with or without antibacterial coating after local percutaneous bacterial inoculations at different concentrations (2 Â 10 5 -2 Â 10 8 ): The plate, the contaminated soft tissues and the underlying bone were removed under sterile conditions after 28 days and quantitatively evaluated for bacterial growth. A stepwise experimental design with an ''up-anddown'' dosage technique was used to adjust the bacterial challenge in the area of the ID50 (50% infection dose). Statistical evaluation of the differences between the infection rates of both groups was performed using the two-sided Fisher exact test ( p < 0.05). Over a period of 6 weeks, a continuous degradation of the PLLA coating of 13%, on average, was seen in vitro in 0.9% NaCl solution. The elution tests on titanium implants with antibiotic or antiseptic coatings produced average release values of 60% of the incorporated antibiotic or 62% of the incorporated antiseptic within the first 60 min. This was followed by a much slower, but nevertheless continuous, release of the incorporated antibiotic and antiseptic over days and weeks. At the end of the test period of 42 days, 20% of the incorporated antibiotic and 15% of the incorporated antiseptic had not yet been released from the coating. The antibacterial effect of the antibiotic/antiseptic is not lost by integrating it into the PLLA coating. The overall infection rate in the in vivo investigation was 50%. For Groups I and II the infection rate was both 83% (10 of 12 animals). In Groups III and IV with antibacterial coating, the infection rate was both 17% (2 of 12 animals). The ID50 in the antibacterial coated Groups III and IV was recorded ...

Antibacterial iodine-supported titanium implants

“…However, hydroxyapatite does not have antimicrobial activity. Some antiseptically-coated implants, such as chlorhexidine, have been reported [47][48][49]. As shown in Table 3, the antibacterial spectrum of iodine is very wide.…”

New Strategies in the Development of Antimicrobial Coatings: The Example of Increasing Usage of Silver and Silver Nanoparticles

“…For instance the application of poly(D,L-lactide) (PDLLA) containing gentamycin on the surface of orthopedic implants drastically decreased the infection rate and a better recovery after infection was observed when compared to systemic gentamycin treatment. The use of mixtures of antibiotics, like rifampicin and fusidic acid in PLLA coatings by Kalicke and coworkers, resulted in effective killing of Staphylococcus aureus infection in a rabbit tibia infection model [60]. Antibiotics have been incorporated in a variety of surface coatings like PVP, polyurethane, polyphosphoester (Politerefate), calcium phosphate (HA).…”

Degradable polymeric materials for osteosynthesis: Tutorial

“…An example is the radiolucent PLDLLA cages used in interbody fusion techniques (Wuisman and Smit, 2006). PLDLLA cages implanted in a small number of patients offered a promising outcome (Kuklo et al, 2004). Although, in this specific case, fast degradation or even complete degradation may not be advantageous, and non-degradable polymers such as poly(etheretherketone) may be more suitable.…”

“…The use of degradable polymers has been proposed for the coating of titanium plates and the local release of loaded antibiotic and antiseptic in a controlled fashion. Coating made of PLLA decreases significantly the rate of infection in vivo due to the degradation of the antibacterial coating and the release of drugs (Kalicke et al, 2006). However, failure or peeling of the coating could potentially be detrimental to bone repair.…”