DEVELOPMENT OF BIO-ACTIVE ARTIFICIAL BONE WITH THE SIMILLAR MECHANICAL PROPERTIES TO NATURAL BONE

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The maximum problem for the artificial bone in orthopaedic surgery is the loosening between materials and natural bones. The purpose of the present research was the devolopment of the artificial bone without the loosening. Here we prepared hydroxyapatite (Ca_<10> (PO_4)_6 (OH)_2 : HA) bio-compatible composites with the selilar mechanical properties to natural bones, then the composites were characterized.(1) Phase transition in hydroxyapatiteThe monoclinic*hexagonal phase transition in the pure and stoichiometric HA was detected at the temperatures from 473K to 483K by X-ray diffraction and thermal analysis.(2) Preparation of hydroxyapatite whiskersHA whiskers were prepared hydrothermally at 200ﾟC from the solution containing calcium and phosphate ions and lactic acid as a chelating agent. The diameter and length of the whiskers were in the range of 1-10 mum and 30-50 mum. The whiskers were slight calcium deficient HA,but the reaction with calcite at 600ﾟC allows the control of Ca/P ra … More tio of the whiskers up to the stoichiometric value of 1.67.(3) Preparation of hydroxyapatite/hydroxyapatite (whiskers) compositesFor the first time in the histry of HA ocmposites, HA reinforced with HA whiskers was prepared by hot-pressing and HIP'ing. This composite had about 100% higher toughness than the non-reinforced pure HA.(4) Preparation of hydroxyapatite/bioactive glass laminated compositesLaminated HA/bioactive glass composits was prepared by hot-pressing. beta-NaCaPO_4 was found as a weak interface belong to high toughness ceramic composites of HA.(5) In vivo reaction for microstructure designed porous ceramics of hydroxyapatite and calcium phosphates Microstructure controlled HA.beta-TCP and HA/beta-TCP porous composites were implanted into the femoral condyles of adult rabbits. New bone formation and bio-degradation of those materials were analyzed quantitatively. The rate of bone formation an bio-degradation depended on the pore size and its distribution and the ratio of HA and beta-TCP. Less