| Objective:The feasibility of repairing infected bone defects by cortico-cancellous graft in I phase was verified by the study of bone regeneration ability and postoperative infection control in the treatment of infectious bone defects.Methods:1.Establishment and diagnosis of chronic osteomyelitis model in rabbit tibia.A 1mm Kirschner wire was used to perforate the tibial side of the rabbit.First,5%sodium cod liver oil was injected into the rabbit's tibia to make local embolism and necrosis.Then,0.1ml(107cfu)SA(Staphylococcus aureus)was injected into the rabbit's cage for 1months to cause chronic osteomyelitis model.The diagnosis was made by imaging,histopathology,bacterial culture,hemogram,immunological analysis,and naked eye observation.2.First stage debridement and bone graft after autogenous iliac bone.96 successful experimental rabbits were divided into groups.The autogenous bone was removed from the iliac bone of the model animal and pruned into the cancellous bone particles,cortico-cancellous bone particles and the cortical bone granules.The animal models of chronic osteomyelitis were thoroughly debrided,including the removal of dead bones,the infection of granulation tissue and surrounding soft tissue,the removal of dead cavity,and the extension of bone defects to more than 1cm.According to the grouping,different kinds of bone particles were implanted into bone defects.They were divided into 4 groups: cancellous bone granule group,cancellous cortical bone granule group,cortical bone granule group and blank group without any filling.3.Detection and evaluation of bone regeneration and revascularization.BMP-2 and VEGF were detected in 4 groups at 1 weeks,2 weeks and 4 weeks after operation,respectively.Immunohistochemistry and Western blot were used to observe the new capillaries in histopathological sections.Statistical analysis drawing.4.Detection and evaluation of anti infection ability.In the case of continuous application of antibiotics,the 4 groups were tested for CRP and PCT of infectious indexes at 1,2 and 4 weeks after bone grafting,and the immunoturbidimetry was used and statistical analysis was used.After 4 weeks of continuous application of sensitive antibiotics,4 groups of bacteria were cultured under sterile conditions,and the infection and pathological sections were observed5.Comparison of the effect of 4 groups on the overall treatment of infectious bone defect.CT scan was performed on the 4 groups at the time of debridement and 4 weeks,8 weeks and 12 weeks after bone graft,and the bone healing was evaluated Results1.The animal model of chronic osteomyelitis: macroscopic observation showed that local skin swelling uplift,ulceration and sinus,sinus self crossing white sticky secretions outflow.Imaging shows: inflammatory hyperplasia of the cortical bone,obvious inflammation in the intramedullary,swelling of the surrounding soft tissue,and increasing inflammatory density.Histopathological observation: infiltration of inflammatory cells,extensive hemorrhage and necrosis in the intramedullary cavity,and invasion of inflammatory cells in the bone cortex.The bacteria culture showed that the bacteria culture was positive,and the serum enzyme was confirmed to be Staphylococcus aureus infection.Hemogram: the number of white blood cells(13.64 + 4.51)109/L.Serum CRP detection:(7.98 + 1.83)mg/L,serum PCT detection:(8.34 + 3.67)ng/ml,all with statistical significance.2.Debridement and bone grafting were successful and satisfactory.They were divided into A cancellous bone group,B cancellous band cortical bone group,C cortical bone group and D blank group according to different bone components.It is successfully placed in a single cage in the animal house.3.Detection and evaluation of bone regeneration and revascularization: BMP-2: the expression of BMP-2 in each group decreased with time and the difference was obvious(P<0.05).Compared to group C and group B at each time point,there was no significant difference in the amount of expression between the C group and the D group(P>0.05).The expressions of A and B two groups at three time points were significantly different from those of C and D groups(P<0.05).VEGF: compared with group A and group B at each time point,there was no significant difference in VEGF expression between group C and D group(P>0.05).The expression of A and B two groups was significantly different from that of group C and D two.The expression level of each group of VEGF at three time points was statistically significant(P<0.05),and the expression level of the 4 groups was the highest in second weeks.4.Detection and evaluation of anti infection ability: CRP: at 1 weeks after bone grafting,the initial detection of CRP was relatively high in the four experimental groups.The level of CRP in group A and group B decreased significantly in 4 weeks(P<0.05)in two groups.In group C and group D,the level of CRP in the two groups was smaller in 4 weeks,but there was no significant difference(P>0.05).PCT: at 1 weeks after bone grafting,the initial value of group A and B was lower,and the difference was not obvious(P>0.05).In group C and group D,the level of PCT was higher at 1 weeks after operation,and there was a significant difference compared with the two groups of A and B(P<0.05).Within 4 weeks,the level of PCT in group A and B decreased significantly(P<0.05),while the PCT level in group C and D two was fluctuated within 4 weeks,but there was no significant difference between the two groups and the 1 week data(P>0.05).The bacteria culture was negative in A and B groups,and the culture of C and D was positive.5.4 groups of infectious bone defects overall treatment effect comparison: through CT and Micro CT observation,after 12 weeks,A and B two groups of bone defect healing,inflammation disappeared,bone cortex smooth and continuous,no periosteal reaction,to achieve bone healing standard.C,D two groups of cortical bone discontinuity,the existence of periosteal reaction and inflammatory performance,does not meet the standard of bone healing.Statistical independent sample t test was used to analyze the bone volume fraction,bone surface area and bone volume ratio,bone trabecular thickness at 4,8 and 12 weeks after bone grafting.The three indexes of A and B two groups were obviously better than those of C and D group(P<0.05),and there was no significant difference between group A and B group(P>0.05).Conclusion:1.The cortico-cancellous bone grafts can effectively repair the infection bone defect after stage I debridement,and the effect is close to the cancellous bone granules.It can solve the problem of the deficiency of the bone mass of the cancellous bone to a certain extent.2.In the treatment of infectious bone defects in stage I debridement autologous bone graft,cancellous bone particles and cortico-cancellous bone particles can be used for the purpose of anti infection in the application of antibiotics,while cortical bone particles can not be used. |
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