Summary: In order to investigate the effect of a new institute-designed absorbable hydroxyapatite microparticles/poly-DL-lactide (HA/PDLLA) fracture fixation devices on experimental fracture healing, 25 rabbits with a...Summary: In order to investigate the effect of a new institute-designed absorbable hydroxyapatite microparticles/poly-DL-lactide (HA/PDLLA) fracture fixation devices on experimental fracture healing, 25 rabbits with a transverse transcondylar osteotomy of the distal femur were fixed in- tramedullary by a HA/PDLLA rod (4. 5 mm in diameter, 30-40 mm in length). The follow-up time lasted 1, 2, 4, 6 and 12 week(s). Roentgenographic, histological and ultrastructural analyses were conducted. The results showed that all osteotomies united within 6 weeks without delay. No accumulation of inflammatory cells was seen. Ultrastructural studies showed that polymorphonuclear neutrophils and macrophages were observed mainly at the 1st week, but only few were noted at the 2nd week. The inflammatory and debridement stages were not prolonged. Large amount of active fibroblasts and some chondroblasts were observed at the 2nd week, suggesting a fibrous callus stage. The main cellularity at 4th week was osteoblasts and osteocytes. Part of osteocytes had already entered the static stage at the 6th week. Our experiment showed that the HA/PDLLA had good biocompatibility, sufficient mechanical strength and caused no delay to the fracture healing.展开更多
The biodegradation and mechanical properties of self-designed hydroxyapatite/poly-DL-lactide (HA/PDLLA) composites were investigated in vitro and in vivo. In vitro, the specimens of HA/PDLLA and unfilled PDLLA with s...The biodegradation and mechanical properties of self-designed hydroxyapatite/poly-DL-lactide (HA/PDLLA) composites were investigated in vitro and in vivo. 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 microstructural 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, 4.5 mm; length, 30 to approximately 40 mm). 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 composites 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. (Author abstract) 5 Refs.展开更多
基金This project was supported by the National Natural Science Foundation of China !(No. 969202011 ) by Hubei Province Natural S
文摘Summary: In order to investigate the effect of a new institute-designed absorbable hydroxyapatite microparticles/poly-DL-lactide (HA/PDLLA) fracture fixation devices on experimental fracture healing, 25 rabbits with a transverse transcondylar osteotomy of the distal femur were fixed in- tramedullary by a HA/PDLLA rod (4. 5 mm in diameter, 30-40 mm in length). The follow-up time lasted 1, 2, 4, 6 and 12 week(s). Roentgenographic, histological and ultrastructural analyses were conducted. The results showed that all osteotomies united within 6 weeks without delay. No accumulation of inflammatory cells was seen. Ultrastructural studies showed that polymorphonuclear neutrophils and macrophages were observed mainly at the 1st week, but only few were noted at the 2nd week. The inflammatory and debridement stages were not prolonged. Large amount of active fibroblasts and some chondroblasts were observed at the 2nd week, suggesting a fibrous callus stage. The main cellularity at 4th week was osteoblasts and osteocytes. Part of osteocytes had already entered the static stage at the 6th week. Our experiment showed that the HA/PDLLA had good biocompatibility, sufficient mechanical strength and caused no delay to the fracture healing.
文摘The biodegradation and mechanical properties of self-designed hydroxyapatite/poly-DL-lactide (HA/PDLLA) composites were investigated in vitro and in vivo. 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 microstructural 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, 4.5 mm; length, 30 to approximately 40 mm). 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 composites 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. (Author abstract) 5 Refs.
