Abstract: PDLLA and HA ultra-fine powders were synthesized by the ring opening polymerization and the liquid phase deposition, respectively. HA/PDLLA composites were prepared by using the liquid phase absorption method. The degradation processes of HA/PDLLA and PDLLA were investigated in vitro and in-vivo. The results show that HA/PDLLA composites have higher mechanical strength and slower degradation rate than pure PDLLA, and avoid losing mechanical strength at the initial implantation stage. The HA granules break off from the surface; fibroblast starts growing and fresh callus come into being. This indicates that HA/PDLIA composites have good biodegradability, certain bioactivity and osteoconductibility. A favorable biocompatibility can be seen on the material/bone interface. At 24 ^th week, the materials are separated and enwrapped by tissue, and the fracture healed up successfully. Consequently, HA/PDLLA composites have sufficient mechanical strength for the fixation of fractures and osteotomies in cancellous bone.

Key words: hydroxyapatite, poly DL-lactide, liquid phase absorption method, biodegradability, interface