Papers by Author: D.J. Hartmann

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Authors: Aurélien Bignon, F. Laurent, J. Goldnadel, Jérôme Chevalier, Gilbert Fantozzi, E. Viguier, T. Roger, Georges Boivin, D.J. Hartmann
Abstract: Despite systemic prophylaxis, infection rates after orthopedic surgery can reach more than 1%. A new HAP/TCP bone substitute loaded with 125 mg of gentamicin was designed for prophylactic use. Its aim was to enhance the efficacy of systemic prophylactic treatments by increasing the local antibiotic concentration. For prophylactic applications, release had to take place within 48 hours not to select antibiotic-resistant bacterial strains. The purpose of this study was to investigate the releasing mechanisms of gentamicin from the porous HAP/TCP matrix. The release rate of gentamicin trough the porosities of the bone substitute was investigated in vitro, in 0.9% sodium chloride solution. The rate appeared to be related to the bone substitute volume and fit classical diffusion laws. All the gentamicin was released in less than 48 hours: this rate corresponds to the recommendations for the prophylactic use of antibiotics.
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Authors: Rami Maksoud, Leila Lefebvre, Laurence Heinrich, Laurent Gremillard, Jérôme Chevalier, D.J. Hartmann
Abstract: The aim of this study was to evaluate the cytocompatibility, cell ingrowth and extracellular matrix deposition of a newly developed porous bioactive glass as a bone substitute. Two types of bioactive glass, different in their pore size (75 and 20 ppi, resp. ~350 and ~1200 $m), were used in this study. The materials were seeded with human osteoblastic (MG63) and fibroblastic (M-228 F01 and M-191 F01) cell lines. The cells were visualized by two techniques, scanning electron microscopy and confocal microscopy. For confocal microscopy cell nuclei were labeled with propidium iodide (IP) and the extracellular matrix components (type I collagen and osteocalcin) by specific antibodies. Cells and matrix were visualized by fluorescence. The bioactive glass used in this study was shown to be non cytotoxic. Cell growth and colonization at the surface and in the depth of the material were observed. Extracellular matrix deposition was also demonstrated which proved the proper biofunctionality of the biomaterial. Scanning electron microscope allowed us to visualize cells at a high magnification at the surface of the bioglass and evidenced that the biomaterials were covered by a sheet of cells with their matrix; on the other hand, confocal microscopy permitted us to observe cell ingrowth and matrix deposition within the depth of the substitute. We showed that extracellular matrix was synthesized mainly in the upper levels where the cell population was the most confluent. In summary, this porous bioglass appears promising for bone substitution.
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