Research On Biocompatibility And Reliability Of Artificial Skull Plate Of Bone Introduced Carbon Fiber Composite

Objective:To creat rabbit skull defect model and to observe the biocompatibility,induced osteogenesis and reliability of induced carbon fiber composite of artificial skull plate in the repair of rabbit skull defect.Methods:1.Grouping Nigty-six rabbits were selected and randomly divided into experimental group(bone inducing factors and carbon fiber composites,Group M)、 experimental control group 1(carbon fiber composites,Group C)、 experimental control group 2(imported titanium plate,Group T)、blank control group(no material was implanted,Group N).2.Operational method The imported material of Group M was thermosetting carbon fiber composite with bone inducing factors of recombinant bone morphogenetic protein 2.The imported material of group C was thermosetting carbon fiber composite alone.Imported titanium plate was in Group T.Group N were only removed bone flaps without implanting material.Carbon fiber composite material was made into the cube whose length was 10 mm and thickness 1mm,with 5 holes of diameter of 1mm.The diameter of titanium plate was 10 mm.After the carbon fiber composite material was sterilized,the osteoinductive factor was added to it by the negative pressure suction and soak method.The materials were kept in a sterile environment of 4℃for use.The defects with a 8 mm diameter of the whole layer were made on the rabbit calvarial bone and the damages to the dura were avoided.The experimental group and the experimental control group 1 and 2were implanted with corresponding materials and fixed.Blank control group were only caused skull defect with no material implantated,and then the scalps were sutured layer by layer.3.Observation index Peripheral blood was taken before operation and at postoperative 2nd,8th and 16 th week respectively for the relevant tests,such as percentage of blood lymphocyte count,serum albumin,total protein,etc.The animals were killed at2 nd,8th and 16 th weeks after operation,and skull CT scan and three-dimensional reconstruction and histological examination were conducted to evaluate the different material biocompatibility and osteogenic property.Results:1.Gross observation Three days after surgery,the wounds were treated with conventional dressing.All the animals’ incisions healed well without swelling.Two weeks later,the incision completely healed.Local hair growth was well,and the incisions were not easy to distinguish with no subcutaneous swelling and scalp necrosis and rupture.The skulls were locally observed after the rabbits were killed.The surface of the material was covered with transparent soft tissue and part of the material was not completely covered.In the blank control group,there was soft tissue covering the bone defect area,which was close to the dura mater and difficult to be separated.The bone margin was clear and no new bone was found.At the 8th week,the callus formation was observed on the surface of materials of group M.There were no obvious callus formation in the other groups.More soft tissue covered in the bone defect area.The material and soft tissue combined so closely that it was hard to observe clearly.Soft tissue increased in bone defect area of blank group,and its texture was more tough,filling defect area.At 16 th week,the combination of materials and soft tissues was tight and not easy to be separated.The soft tissue in the blank group was close to the surrounding tissue,which was difficult to distinguish.There was much more callus formation in every group than that of perspective group before.2.Peripheral blood examination The test results of lymphocyte percentage,urea nitrogen,alanine aminotrans Ferase and Ca2+ showed that:there was no significant difference between these groups on the surgery day and 2,8,16 weeks after the operation.albumin and total protein analysis: There was significant difference in the 2nd week,the8 th week and the 16 th week after operation.There was no difference in the corresponding time points between groups.The results of osteocalcin analysis showed that the postoperative level of each group was higher than that before operation,the difference was statistically significant.At 2nd and 8th week after operation,the level of M group was higher than that of other groups,the difference was statistically significant.There was no significant difference among other groups.At sixteenth weeks after operation,there was no difference between the two groups.The results of alkaline phosphatase analysis showed that at second weeks after operation,the levels were higher than those before operation,the difference was statistically significant.At 8th and 16 th week after operation,the level of M group was higher than that before operation,and the levels of other groups were similar or lower than those before operation.3.CT thin layer scanning of skull At 2nd week after operation,the defects in each group were obvious,a small amount of new bone was formed,and the area of defect was decreased.In group T,the bone defect area was obviously observed.At 8 weeks,the situation of each group was significantly improved compared with the corresponding group at 2nd week after operation.The defect area of M group was smaller than that of other groups.At 16 weeks,the margin of each group was indistinct.But still small area bone defect was still observed.The defect area of M group was smaller than that of other groups,but there was no significant difference between the groups at 16 weeks.4.Local histological examination of skull defect The local tissues were examined by histological HE staining to observe the local inflammatory reaction and the formation of new bone tissue.It was saw that the growth rate of new bone in M group was faster than that in other groups,but in the later stage the situation was basically the same.There were local neovascularization,fibrous tissue formation,but no obvious inflammatory response.Conclusion:1.The establishment of animal model of skull defect can meet the relevant properties of materials.The comparison between the conventional titanium alloy and carbon fiber composite has some innovation.2.The results of animal experiments showed that the material had good biocompatibility and could meet the requirement of slow release of bone inducing factor.3.The porous structure of the composite,its load inducing factor,has a slow release effect on bone inducing factor,can promote osteogenesis for a long time,shorten the time of bone repair.