Gentamicin coating of plasma chemical oxidized titanium alloy prevents implant-related osteomyelitis in rats.

Implant related infection is one of the most feared and devastating complication associated with the use of orthopaedic implant devices. Development of anti-infective surfaces is the main strategy to prevent implant contamination, biofilm formation and implant related osteomyelitis. A second concern in orthopaedics is insufficient osseointegration of uncemented implant devices. Recently, we reported on a macroporous titanium-oxide surface (bioactive TiOB) which increases osseointegration and implant fixation. To combine enhanced osseointegration and antibacterial function, the TiOB surfaces were, in addition, modified with a gentamicin coating. A rat osteomyelitis model with bilateral placement of titanium alloy implants was employed to analyse the prophylactic effect of gentamicin-sodiumdodecylsulfate (SDS) and gentamicin-tannic acid coatings in vivo. 20 rats were randomly assigned to four groups: (A) titanium alloy; PBS inoculum (negative control), (B) titanium alloy, Staphylococcus aureus inoculum (positive control), (C) bioactive TiOB with gentamicin-SDS and (D) bioactive TiOB plus gentamicin-tannic acid coating. Contamination of implants, bacterial load of bone powder and radiographic as well as histological signs of implant-related osteomyelitis were evaluated after four weeks. Gentamicin-SDS coating prevented implant contamination in 10 of 10 tibiae and gentamicin-tannic acid coating in 9 of 10 tibiae (infection prophylaxis rate 100% and 90% of cases, respectively). In Group (D) one implant showed colonisation of bacteria (swab of entry point and roll-out test positive for S. aureus). The interobserver reliability showed no difference in the histologic and radiographic osteomyelitis scores. In both gentamicin coated groups, a significant reduction of the histological osteomyelitis score (geometric mean values: C = 0.111 ± 0.023; D = 0.056 ± 0.006) compared to the positive control group (B: 0.244 ± 0.015; p < 0.05) was observed. The radiographic osteomyelitis scores confirmed these histological findings.

[Preparation and in-vitro analysis of a polyethylenimine coating on hernia meshes]. / Herstellung und In-vitro-Analyse einer Polyethylenimin-Beschichtung auf Herniennetzen.

BACKGROUND: Certain coatings such as titanium may improve the biocompatibility of hernia meshes. The coating with biopolymers such as polyethylenimine (PEI) can also improve the material characteristics of implants. This approach has, however, not yet been explored. Thus, it was the aim of the present work to clarify if and how hernia meshes with their three-dimensional structure can be successfully coated with PEI and with which technique this coating can be best analysed. METHODS: Commercially available meshes made from polypropylene, polyester and ePTFE have been coated with PEI. The coating was analysed via cell proliferation test (mouse fibroblasts), electron microscopy, X-ray photoelectron spectroscopy (XPS) and fluorescence microscopy. Cell viability and cytotoxicity were tested by the MTT test. RESULTS: With the PEI surface modification, mouse fibroblasts grow faster and in greater numbers on the mesh surface. XPS as well as fluorescence microscopy show weaknesses in their applicability and meaningfulness because of the three-dimensional mesh structure while XPS showed overall better results. Optical proof in the electron microscope after cell fixation was not unambiguously accomplished with the techniques used here. In the MTT test, no cellular damage from the PEI coating was detected after 24 hours. CONCLUSION: The present results show for the first time that PEI coating of hernia meshes is possible and effective. The PEI coating can be achieved in a fast and cost-efficient way. Further investigations are necessary with respect to coating quality and cytotoxicity before such a coating may be used in the clinical routine. In conclusion, PEI is a promising polymer that warrants further research as a coating for medical implants.