Osteogenic properties of calcium phosphate ceramics and fibrin glue based composites.

Calcium phosphate (Ca-P) ceramics are currently used in various types of orthopaedic and maxillofacial applications because of their osteoconductive properties. Fibrin glue is also used in surgery due to its haemostatic, chemotactic and mitogenic properties and also as scaffolds for cell culture and transplantation. In order to adapt to surgical sites, bioceramics are shaped in blocks or granules and preferably in porous forms. Combining these bioceramics with fibrin glue provides a mouldable and self-hardening composite biomaterial. The aim of this work is to study the osteogenic properties of this composite material using two different animal models. The formation of newly formed bone (osteoinduction) and bone healing capacity (osteconduction) have been study in the paravertebral muscles of sheep and in critical sized defects in the femoral condyle of rabbits, respectively. The different implantations sites were filled with composite material associating Ca-P granules and fibrin glue. Ca-P granules of 1-2 mm were composed with 60% of hydroxyapatite and 40% of beta tricalcium phosphate in weight. The fibrin glue was composed of fibrinogen, thrombin and other biological factors. After both intramuscular or intraosseous implantations for 24 weeks and 3, 6, 12 and 24 weeks, samples were analyzed using histology and histomorphometry and mechanical test. In all cases, the newly formed bone was observed in close contact and around the ceramic granules. Depending on method of quantification, 6.7% (with BSEM) or 17% (with micro CT) of bone had formed in the sheep muscles and around 40% in the critical sized bone rabbit defect after 24 weeks. The Ca-P/fibrin material could be used for filling bone cavities in various clinical indications.