Papers by Author: Xavier Bourges

Abstract: We have developed a new injectable bone substitute combining specific granules of BCP with or without radiopaque elements with a reversible thermo sensitive resorbable carrier such as Pluronic F-127. The composite is liquid at ambient temperature and set as hydrogel at 37°C. Rabbit experiment demonstrates high biocompatibility and bone ingrowth at the expense of the injectable bioceramic composite.

Abstract: We have developed a novel macroporous calcium phosphate cement MCPC® that sets to poorly crystalline apatite after mixing the powder component with an aqueous solution and has interconnective macroporosity We performed cranioplasty on rat model by injecting the new macroporous calcium phosphate cement MCPC®. The mechanical property of the cement is about 12MPa after 24 hours (compression test). The cement matrix is totally transformed into poorly crystalline apatite in 48 hours. This study demonstrates that MCPC® cement was suitable and efficient for parietal bone reconstruction. Its injectability and moldability allows to be used in bone reconstruction surgery and its mechanical properties are compatible to support calvarial reconstruction. In addition, a bone ingrowth onto the BCP granules occurred on time.

Abstract: Surface roughness modulates the osseointegration of orthopaedic and dental titanium implants. High surface roughness is currently obtained by blasting of titanium implants with silica or aluminium abrasive particles. This process includes into the surface abrasive particles and may cause the release of cytotoxic silica or aluminium ions in the peri implant tissue. To overcome this drawback, we currently develop an innovative gridblasting process using Biphasic Calcium Phosphate (BCP) particles (RBBM Resorbable and Biocompatible Blast Media) to generate biocompatible roughened titanium surface. This work present the technique of blasting using RBBM particles to provide a roughened surface which does not release cytotoxic elements and (ii) to assess the effects of such a roughened surface for bone osteointegration in critical size rabbit defect. Our results demonstrate that resorbable biphasic calcium phosphate abrasive particles can be used to create titanium surface roughness. This grid blasting process increases surface roughness of titanium implants and offers a non cytotoxic surface for rapid and efficient osteointegration.

Abstract: Dedicated to Minimal Invasive Surgery MIS particularly in spine for vertebroplasty, the surgeons and radiologists ask for improvement of radio opacity, to be sure of the injection site, and to prevent injection in blood vessels. MBCP Gel® is an Injectible biomaterial non self hardening, the biomaterials consists of BCP granules associated with a hydrosoluble polymer. These materials have been shown to be perfectly biocompatible and potentially resorbable and, thanks to their initial plasticity, they assume the shape of the bone defects very easily, eliminating the need to shape the material to adjust to the implantation site. MBCP gels do not have mechanical properties like the hydraulic bone cements. However bone cells are able to invade the spaces created by the disappearance of the polymer carrier. Bone ingrowth takes place all around the granules at the expense of the resorption of the BCP granules. In time, the mechanical property is increased due to the presence of the newly formed bone. This study demonstrates an improvement of MBCP gel by freeze drying and reconstitution using iodine solution or sterile water in a classical model of rabbit bone defects.

Abstract: We have performed and evaluated a composite combining PL DLLA and PCa able to have a better control of the hydrolysis and maintain of the mechanical property on time, until wound healing was achieved. Bioabsorbable osteoconductive composite is devoted to the development of resorbable osteosynthesis for spine and osteoarticular surgeries. Such resorbable osteosynthesis will be associated to new bone substitute having high osteogenic property but without initial mechanical property. The purpose of this study was to evaluate the resorption kinetic of a composite using PL DLLA (Poly [L-Lactide-co-D,L-Lactide] acide) charged with PCa granules and the interaction with injectable bioceramic without self hardening. MBCP gel® is a composite associating a mineral phase of an intimate nanoscale melting of hydroxyapatite and beta tri calcium phosphate and an aqueous phase containing a synthetic polymer derived from cellulose HPMC (hydroxyl propyl methyl cellulose).

Abstract: Resorbable osteosynthesis based on PLLA and derivatives will be associated to bone substitute for bone reconstruction. We have performed rand evaluated a composite combining PL DLLA and Biphasic calcium phosphate able to have a), a better controlled hydrolysis in the purpose to preserve on time the mechanical property, and b), for long term efficiency, bone ingrowth at the expense of the osteosynthesis and the associated bone substitute. A new calcium phosphate cement MCPC® was tested with such composite. The novel macroporous calcium phosphate cement MCPC sets to poorly crystalline apatite after mixing the powder component and an aqueous solution. Interconnective macroporosity was induced on time by resorption of one part of the MCPC®. The multiphasic calcium phosphate components in the cement, are resorbed at different rates allowing the replacement by newly formed bone. This study reports the biocompatibility and the interactions of a composite using PL DLLA (Poly [L-Lactide-co-D,L-Lactide] acid) charged with biphasic calcium phosphate granules and a self setting calcium phosphate cement of new generation.

Abstract: We performed vertebroplasty on goat model by injecting a new macroporous calcium phosphate cement MCPC®. The mechanical property of the cement is about 12MPa after 24 hours (compression test). The cement matrix is totally transformed into poorly crystallized apatite in 48 hours. This study demonstrates that MCPC cement was suitable and efficient for a spine application. Its injectability allows to be used in mini invasive surgery and its mechanical properties are compatible to support spine strength. In addition, a bone ingrowth onto the BCP granules occurred with time.

Abstract: The purpose of this study ass to investigate the addition of round 80-200m granules shape radiopaque agents (RA) to synthetic Injectable Bone Substitute to improve contrast performance for minimal invasive surgery MIS. Composites were obtained by mixing BaSO4, Bi2O3, Lu2O3 or GdPO4 with calcium deficient apatite CDA which decompose during sintering process in BCP (60% HA, 40% β-TCP). Each composite was characterized: by XRD, FTIR. Biocompatibility was tested in vitro and in vivo in bony site (3 weeks implantation in rats). Primary results show that the suitable radiopaque BCP/RA composite (radiopacity intensity, biological responses) appeared to be BCP/Ba. Next works will complete the current studies on biological performance in association with different kind of resorbable injectable bone substitute as suspension, gel or calcium phosphate cements.