BIODEGRADATION AND MECHANICAL PROPERTIES OF HYDROXYAPATITE/POLY-DL-LACTIDE COMPOSITES FOR FRACTURE FIXATION
摘要
The biodegradation and mechanical properties of self-designed hydroxyapatite/poly-DL-lactide (HA/PDLLA) compositites -were investigated in vitro and invio. In vitro, the specimens of HA/PDLLA and unfilled PDLLA -with similar molecular weights were immersed in phosphate-buffered saline. Ageing of the various devices were monitored by measuring molecular weight,water absorption, weight loss, PH, mechanical strengths and mi-crostructural changes. The follow-up times were 2, 4 , 6 , 8, 10 and 12 weeks. In vivo, a transverse transcondylar osteotomy of the distal femur was fixed with a HA/PDLLA rod (diameter, 4. 5mm;length, 30-40mm). The follow-up times were 3. 6 and 12 weeks. Roentgenographic, histologic, and biomechanical studies were carried out. The results show that the HA/PDLLA composities have higher mechanical strength and slower degradation than that of the unfilled PDLLA and that of all osteotomies unite within six weeks without delay. Consequently, the HA/PDLLA composites possess sufficient mechanical strength for the fixation of cancellous osteotomies.