The Effect And Related Mechanism Of Swan-like Memory Pressure Connector On Experimental Fracture Healing

The study tried to investigate the effect and related mechanism of Swan-like Memory-pressure Connector(SMC) on experimental fracture healing, so as to provide the theoreticbase for the uses of SMC in clinic and popularize the SMC.Fifty adult dogs were used in this study. Bilateral femora were osteomized in the middleand fixed with SMC, Compression Plate(CP), Intramedullary Nail(IN) respectively. Animalswere sacrificed at 1,2,4,8,12 weeks after operation. The biologic behavior and ultrastructureof the cell in the fracture-site were observed dynamically by using light microscopy(LM) andtransmission electron microscopy(TEM). The amounts of bone in different time of bonehealing were analysised quantitatively under roentgen rays examination and histomorphologicstudy. The mechanical properties of bone fixed with three internal fixation were tested. Theresults are as following:1 .At one week after operation, Anatomical reduction was achieved in three groups. Thefracture line were observed in 3 groups at 2 weeks after fixation. At 4 weeks postimplantation, the fracture gap disappeared because of the formation of slight bridging callusin SMC group. The narrow fracture line were presented in CP group. Slight external calluswere observed in IN group. After 8 weeks, primary gap healing occurred without periostealcallus and bony absorption in SMC group. The gradual disappearance of the fracture lineoccurred with the lack of external callus, but osteoporosis emerged under the plate in CP. Aexternal fusiform callus were observed in IN. At 12 weeks after operation, A perfect boneunion was achieved in SMC group without external callus and osteoporosis. Bone healingfinished in CP group, but the cortex was thinner than early phase and the medullary cavitywas enlarged. The remodeling of callus was to be continued in IN group.2.The histological and ultrastructural results showed that the organizing hematoma wereobserved in the fracture-site at 1 week after operation. The component of cells in hematoma3was same in three groups, and a great quantity of neonate blood vessel were emerged in SMC.After 2? weeks, the amounts of the osteoblast and chondroblast in medullary callus in SMCgroup were more than the other's. These osteoblast and chondroblast had abundant roughendoplasmic reticulum(RER) with their tune expanding extremely. It demonstrated that thefunction of osteoblast and chondroblast in medullary callus in SMC group were actively. By 8weeks post-implantation, there was the lamellar bone substitute the woven bone in SMCgroup. While in the case of CP, the bony absorbed cavities and osteocyts entered intodegenerative phase were observed in cortical bone underneath CR The osseous callus brigdedthe fragments of fracture and the new cartilage were almost ossified in IN group. 12 weekspost operation, a small number of bony absorbed cavities were formed underneath SMC, thebony absorbed cavities underneath CP were enlarged remarkably. The subperiosteal cellproliferation ceased in IN.3. The quantitative histomorphological results showed that the amounts of new bone andthe thickness of cortex in fracture fragments were no significant difference among three groupat early stage after operation. 4 weeks post operation, the amounts of new bone and thethickness of cortex in SMC group was highest, the IN's took second place, and the CP's waslowest. There was a significant difference among three group. At 8 weeks after operation, thequantity of new bone in SMC group were higher than the CP group's and IN group's, thestatistical difference could be found. The highest thickness of osteomized cortex thicknesswas in SMC group, the second was in IN group, and the lowest was in CP group. 12 weekspost operation, the quantity of new bone in SMC group were higher than the CP g...