Animal Experimental Study Of Self-locking Cerclage Band Made Of Poly-DL-lactic Acid Affect The None Weight-bearing Fractures

Objective:To study the application of self-locking cerclage band made of poly-DL-lactic acid in the fixation of none weight-bearing fractures through animal experiments. The effects of PDLLA on the fixation and the impact on fracture healing were observedMethods:80 rabbits were randomly divided into two groups. Femur fractures of the none weight-bearing models were made. Fractures were fixed using self-locking cerclage band made of poly-DL-lactic acid in experimental group and metal fixation material in control group. The clinic effects of the two groups were evaluated and compared through the gross observation, radiographic, histologic examination after 2, 4, 8 and 12 weeks respectively.Results:The experimental results suggested that fibrous callus formatted arounding the cerclage band after 2 weeks. While there were no fibrous callus in control group. Radiographic examination in experimental group showed much callus than that in control group(P<0.05). After 4 weeks, Gross observation showed large amount of new bone trabeculae in two groups. Complications such as loosening, breakage were not observed. After 8 weeks,12 weeks, Fracture healing was achieved and implant was wrapped by callus. The structure of woven bone and the arrangement of bone trabecula were better with time. The absorption of bone necrosis was not found in the two groups. Radiographic examination shows callus were no difference between two groups at 4,8,12 weeks after fracture (P>0.05).Conclusion:The self-locking cerclage band made of poly-DL-lactic acid could be used in the treatment of none weight-bearing fractures. The results of fixation were better and there was advantage on fracture healing. Objective:To study the effect of self-locking cerclage band made of poly-DL-lactic acid in the fixation on bone healing and expression of Vascular endothelial growth factor (VEGF).Methods:80 rabbits were randomly divided into two groups. Femur fractures of the none weight-bearing models were made. Fractures were fixed using self-locking cerclage band made of poly-DL-lactic acid in experimental group and metal fixation material in control group. The expression of VEGF and CD34 after 2,4,8,12weeks were detected by the immunohistochemistry and Western blot. Results:The levels of VEGF protein in the experimental group were higher in vascular endothelial cells, fibroblasts, osteoblasts, cartilage cells than those in.the control group at 2 weeks after fracture (P< 0.05).The levels of VEGF protein were no difference between two groups at 4,8,12 weeks after fracture(P>0.05). A large number of strong positive staining of cells was detected by the immunohistochemistry in experimental group and control group. But mean optical density value and microvessel density were significantly increased in experimental group at 2 weeks (P<0.05).While mean optical density value and microvessel density were no difference between two groups at 4,8,12 weeks after fracture (P>0.05).Conclusion: There were better effect on reconstruction of blood circulation at the fracture and fracture healing with self-locking cerclage band made of poly-DL-lactic acid fixed.