Papers by Author: Olivier Gauthier

Abstract: The integration of drugs and devices is a growing force in the medical industry. The incorporation of pharmaceutical products not only promises to expand the therapeutic scope of device technology but to access combination products whose therapeutic value stem equally from both the structural attributes of the device and the intrinsic therapy of the drug. For example, the orthopedic industry is exploring drug-coated hip, knee and bone reconstruction implants capable of promoting healing as an added therapeutic benefit for device recipients. In this context, the drug is eluted locally, being targeted in a specific site of interest, thus offering a convenient strategy to avoid adverse effects commonly observed for systemic treatments of some diseases, as an additional benefit. In addition, these new technologies are generally well adapted to the development of minimally invasive surgery for their implantation. In this context, given the wide use of calcium phosphates (CaPs) and bisphosphonates (BPs) for the therapy of bone-related affections, there was great interest to investigate the chemistry taking place when combining the two systems since: (i) it could provide better insight in the mechanism of BP fixation on bones (ii) such combination could act as efficient BP delivery systems when implanted in bone defects.

Abstract: Autologous bone chips are widely used in orthopedic surgery to fill large defects due to osteoinductive property but are limited in quantity. Several groups have reported the formation of mineralized bone after implantation of bioceramics in ectopic sites of different animals. However, osteoinduction by bioceramics has not yet proved to be equivalent to those of autologous bone. In this study, we compare the bone inducing capability of autologous bone chips and synthetic biphasic calcium phosphate (BCP) ceramics granules sintered at various temperatures. Both materials were implanted in muscles and femurs of goats inside hollow containers for 6, 12 and 24 weeks and analyzed by histology. This study showed that bone tissue formed in contact with micro porous ceramics sintered at low temperature as well as autologous bone chips both in ectopic and intrafemoral sites of goats.

Abstract: Bone invasion is common in case of Squamous Cell Carcinomas (SCC) of the upper aero-digestive tract. Radiotherapy is required in addition to large surgical tumor removal. This treatment usually generates irreversible injuries on the reparation properties of the tissues, especially on bone. The quality of life of patients undergoing major surgery and radiotherapy in maxillary and mandible areas is reduced, but could be improved by bone reconstruction. The aim of this study was to evaluate the bone reconstruction possibilities by Macroporous Biphasic Calcium-Phosphate (MBCPÔ). The MBCP substitute was evaluated as granules and associated to autologous bone marrow (BM) graft in irradiated areas, in an inbreeding rodent model. Radiation sequels were created on inferior members of half of the rats. 3 weeks later, 3-mm osseous defects were created on each animal. The inbreeding model allows BM to be grafted without graft-versus-host reaction. Defects were filled either with MBCP alone, BM alone or a mixture of MBCP and BM. Six weeks after implantation, animals were sacrificed: bone repair and ceramic degradation were evaluated by qualitative and quantitative study. Results showed that bioceramics were well osteointegrated. Filling the defects with BM alone showed a significant increased of newly-formed bone formation but only after irradiation, whereas filling defects with MBCP alone increased new-bone formation only without previous irradiation. Associating MBCP to BM provided the best new-bone formation rates after irradiation. Degradation of the ceramic was the most important in case of BM grafting. This study demonstrated that BM added to MBCP constitute an appropriate material to be considered in case of bone defect occurring in irradiated tissue, and could be foreseen for use after bone removal for oncologic obligations.