リン酸三カルシウム/ポリ乳酸スクリューの力学的特性に及ぼす熱間鍛造条件の影響

抄録

Metal bone fixation devices used for fracture treatment have a higher elastic modulus than that of autogenous bone. However , this high modulus weakes the surrounding bone. Therefore, we focused on a composite material of poly(lactic acid) (PLA) and tricalcium phosphate (TCP), because a bioabsorbable material with an elastic modulus similar to that of natural bone. However, apprication of TCP/PLA composite is difficult because of lower strength. Therefore, we focused on drawing to improve the strength. However, it is difficult to form complex shape such as screw. In this study, TCP/PLA screws were molded by hot forging, and the strength of this screws are eveluated for shear and torsion tests. The results of shear test showed that shear strength increased extrusion ratio (ER) in hot forging. The shear strength decreased with increasing TCP content. On the other hand, the shear strength of the TCP/PLA screw increased with hot forging, and the strength at ER8 and TCP content 15 mass% achieved higher strength than that of without forging and 0 mass%. Torsion test results indicated that the addition of TCP inhibited axial orientation. The maximum torsional moment increased with TCP content.