[Animal implantation with a new type of chitosan microspheres/calcium phosphate cement]

To investigate bioactivity, biodegradation, bone conductive properties, and clinical maneuverability of a novel injectable chitosan microspheres/calcium phosphate cement (CPC).

The bone defect of pi x 4 mmx4 mmx6 mm was made at both thigh bones of 12 rabbits, and experimental material (chitosan microspheres/CPC) or control material (alpha-tricalcium phosphate cement, alpha-TCP) was injected into the defect respectively. The filling situation was evaluated by X-ray 3 days after operation. The rabbits were divided into three groups, four for each group. The samples with chitosan microspheres and the control with alpha-TCP were collected at 8, 16, 24 weeks after operation. Histological examination and scanning electron microscope (SEM) evaluation were performed.

The absorption of implants with chitosan microspheres was observed at 8 weeks, and became more apparent at 16 weeks. Different size of cavities were observed in CPC after the degradation of chitosan microspheres. The chitosan microspheres/CPC was dramatically degraded after 24 weeks with a few chitosan microspheres, and new bone replaced the degraded materials. The implants with alpha-TCP were absorbed slowly compared with the chitosan microspheres/CPC. The cavities in alpha-TCP were small.

The chitosan microspheres/calcium phosphate cement has the characters of good biocompatible and osteocombinative ability. Compared with the control material, adding chitosan microspheres into CPC could enhance its degradability and facilitate the new bone formation.