BIOACTIVITY OF BIORESORBABLE OSTEOSYNTHETIC DEVICES MADE OF HYDROXYAPATITE/ POLY-DL- LACTIDE COMPOSITES: AN EXPERIMENTAL STUDY

摘要

Aim. To investigate the bioactivity of the self- designed biodegradable osteosynthetic devices made of resorbable hydroxyapatite microparticles/ poly- DL- lactide (HA/PDLLA) composites. Method. Forty- three rabbits with a transverse transcondylar osteotomy of the distal femur were fixed intramedullary by a HA/PDLLA rod, the duration of follow- up were 3， 6， 12, 24 and 36 weeks. Histological, scanning electron microscopic (SEM), energy dispersive X- ray (EDX) and biomechanical analyses were done. Results. Active new bone formation and direct bone- bonding were seen at the bone- implant interface. Generous apatite crystals deposited and grew on the surface of the composites at 3～ 6 weeks postoperation. The interfacial shear strength increased significantly. Conclusion. Through the incorporating of resorbable HA microparticles, specific bone- bonding and active osteogenic capacity is introduced. This kind of bioactivity, together with other properties such as sufficient mechanical strength, enhanced biocompatibility and radiopacity, which are intrinsically unobtainable in totally resorbable polymer/polymer systems, make the HA/PDLLA composites become a desirable material for the internal fixation of cancellous bone.