Assessment of the suitability of a new composite as a bone defect filler in a rabbit model

To assess the suitability of clinical application of a new composite consisting of calcium phosphate cement (CPC), chitosan fibre and gelatin, a bilateral supracondyle hole defect (5 mm in diameter) was developed in the femurs of 40 New Zealand white rabbits and filled with either the composite or CPC. Macroscopic, radiological, histological and histomorphometric evaluations were performed at the time points of 1, 3, 6 and 12 months post-operation. New bone formation of the composite group was 46.5 +/- 3.2% within 12 months, while that of the CPC group was 12.4 +/- 2.7% (p < 0.05). No adverse response was found in either group. In addition, it was very interesting that the new bone grew into the implant only in the composite group. By histochemical staining we found that chitosan fibre was surrounded by monocytes and macrophages after 3 months. Overall, our study demonstrated that both CPC and the composite had osteoconductive characteristics and good biocompatibility, but the composite presented superior bioresorbability and a higher rate of new bone formation.