Repair of segmental bone defects in rabbit tibiae using a complex of β-tricalcium phosphate, type I collagen, and fibroblast growth factor-2

The objective of this study was to evaluate the effects of a complex of β-tricalcium phosphate (β-TCP) granules, collagen, and fibroblast growth factor-2 (FGF-2) on cortical bone repair in rabbits. Segmental bone defects of 5 mm in length were created in the middle of the tibial shaft. The defect was stabilized with a plate and screws, and was filled with 0.3 ml of a complex of β-TCP granules and 5% collagen, with or without 200 μg of recombinant human fibroblast growth factor-2 (rhFGF-2). Bone regeneration and β-TCP resorption were assessed by X-ray and micro-CT scanner. A three-point bending test was also performed. The results showed that the segmental bone defect was not only radiologically, but also mechanically healed with cortical bone 12 weeks after implantation of the complex with rhFGF-2. In contrast, after implantation of the complex without rhFGF-2, most of the defect was filled with β-TCP and only a small amount of bone formation was found. These results suggest that resorption of β-TCP is important for bone formation and may be promoted by FGF-2 in the β-TCP implantation site. In addition, the complex of β-TCP granules and collagen combined with rhFGF-2 provides a paste-like material that is easy to handle. This material may be of considerable use in the treatment of cortical bone defects.