| Objective: 1, To study the bonding strength of octyl-a-cyanoacrylate,the biomechanics characteristics of octyl-a-cyanoacrylate adhensive bonding the transverse fracture and butter-fly fracture fragment in middle part of tibia shaft. 2, Observe the cytotoxicity of octyl-a-cyanoacrylate to human osteoblastic cell,observe the effect of octyl-a-cyanoacrylate steep solution on cellular viability by cell count,MTT assay and clony-forming assay. 3, Observe the result of octyl-a-cyanoacrylate adhensive bond tibial fracture, the influence on fracture healing,the speed of degradation and the detection of it's production.Method: 1, Firstly,make the transverse fracture model on fresh human tibia shaft, after bonded for 24 hour,test the tensile strength and shear strength;then a 90 butter-fly fracture fragment was made in the middle part of tibia by bandsaw. The compression stress,torsional stress and angular deflection was performed before and after osteoectomy respectively .After bonded by octyl-a-cyanoacrylate adhesive , the compression, torsional stress and angular deflection was tested again,to observe the biomechanic influence of the fragment on the tibia shaft before and after bonded bvoctyl-a-cyanoacrylate. 2> In vitro cultured the osteoblastic cells from human iliac bone and identified the ALP secretion of the osteoblastic cell.Inoculate the osteoblastic cells in 25ml flash by the density of 5X 104/ml.Each bottle use different concentration of steep salution from 100%, 50%, 25%, 10%, 5%, 1%, and normal 10% FCS DMEM culture medium, each concentration 3 bottles.At the time of 1 ,3 ,5 days after inoculation, digested by 0.25% Pancreatin and dyeing by 0.4% trypan blue solution, count the dead cell and the number of total cell number. Inoculate 1000 oseoblastic cells in 6-well plate with different concention of steep solution, calculated the adhibiting rate after 24 hours, observe the clony formation of the osteoblastic cell after cultured for lOdays.Inoculate osteoblastic cell at the density of 2X104 per well in a 6-well micrototre plate .Each steep solution concentration 4 wells, cultured for 1 to 5 days, measured the OD value every day,observed the effect of the different concentration of steep solution on cell growth. 3-. Make transverse fracture at the tibia of rabbit.The experiment group fixed by Kirschner wire and octyl-a-cyanoacrylate adhensive, the control group by Kirschner wire only.Harvest the specimen at the 2, 4, 6, 8, 10,12week after operation,observe the fracture healing, the speed of degradation and theproduction of degradation.Result: 1> The tensile strength of octyl-a-cyanoacrylate is 5.93MPa,theshear strength is 9.11MPa.The butter-fly fracture fragment decreased the bending strength,torsional strength,compressive strength of tibia shaft.In torsional test ,the torque of tibia before osteoectomy is greater than bonded tibia,the bonded tibia is greater than the unbonded tibia.In compressive test,before adhensive broken,the compressive curve slope of tibia beforeosteoectomy is greater than that of bonded tibia,the bonded tibia is greater than the unbonded tibia. In angular deflection test before adhensive broken,the curve slope of tibia before osteoectomy is greater than bonded tibia,the bonded tibia is greater than unbonded tibia.The elastic modulus > rigidity coefficient and moment of area inertia of the bonded tibia and tibia before osteoectomy have no statistic difference. The octyl-a-cyanoacrylate adhensive bond the fracture fragment could improve the bending strength, torsional strength,compressive strength of tibia bone. Under compressive stress,the slope of compressive curve of the tibia before osteoectomy is higher than the bonded tibia;and the slope of compressive curve of the bonded tibia is higher than the unbonded tibia.The compressive stress distribute on the bonded fracture fragment is 47.2% of total compressive stress,3.75KN. 2-. 81.6% of osteoblastic cell from the iliac bone express ALP at the primary generation, 83.5% and 86.4% at the 2nd and third generation.In different concentration of octyl-a-cyanoacrylate steep solution, the adhibiting rate and colony-formaing rate> cell viability have no statistic difference. The OD value of MTT assay gradually increased during the 5 days'culture, each group in the same time have no statistic difference.The cytotoxicity of each group less than 1. 3^ After bonded by octyl-a-cyanoacrylate,the adhensive completely degrade at the 8 weeks after operation.The formaldehyde was not detected by oscillogra trac reade Polarographic ? Compare with the controll group, the fracture healing have no statistic difference.Conclusion:! ^ Though octyl-a-cyanoacrylate adhensive have good bonding strength,but it is not enough for the fixation of tranverse fracture.When bonded the butter-fly fracture of middle part of tibia shaft, itcan increase the compressive strength,torsion strength and angular strength. 2, The octyl-a-cyanoacrylate adhensive has no obvious cytotoxicity on osteoblastic cell.The cytotoxicity of each group of octyl-a-cyanoacrylate adhensive steep solution less than 1 ,meet the requirement of China standard biological evaluation of medical devices. 3 , The octyl-a-cyanoacrylate degrade within 8 weeks after operation. Formaldehyde was not detected by oscillogra trac reade Polarographic at each time group.There are no adverse effect of octyl-a-cyanoacrylate on fracture healing was observed.
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