Experiment Studying Of The Accordion Technique In The Treatment Of Rabbit Tibial Nonunion

Objective:To establish the animal model of the Accordion Technique in the treatment of rabbit tibial nonunion,and to provide a theoretical basis for the clinical treatment of the nonunion of the Accordion Technique.Methods:26 adult New Zealand white rabbits were prepared for the experiment.The model of rabbit tibial nonunion was established by retaining fragments of 2mm gap,scraping the outer periosteum and the local bone marrow,performing cauterization of the broken ends,and fixing with an ring external fixator.After 8 weeks,2 model rabbits were randomly selected for receiving X-ray and histological examine to observe the bone healing.The remaining 24 rabbits were divided equally and randomly into three groups: the control group(only ring external fixator),the simple compression group(compression at a rate of 0.50 mm/d for 6 days)and the Accordion technique group(compression at a rate of 0.50 mm/d for 6 days,followed by distraction at same speed for 6 days,then a second compression was done for 6 days,and there was a 6-day latent period between compression and distraction).Callus growth and bone healing progress were assessed by X-ray and histological examine.Micro-CT was used for 3-D resconstruction and quantitative analyze of Bone Volume(BV),Bone Volume/Tissue Volume(BV/TV),Trabecular number(Tb.N),Trabecular thinkness(Tb.Th),and Trabecular separation(Tb.Sp).Results:1.The X-ray and histological examine of the fracture site suggested that nonunion appeared at all model rabbits after 8 weeks.2.Radiological and histological analyses showed that both simple compression technique and Accordion technique can promote bone regeneration in nonunion site,but the effect of Accordion technique is better.3.Results of quantitative analyze by Micro-CT suggested: the BV,BV/TV,and Tb.N of the Accordion technique group and the simple compression group were higher than the control group,the difference was statistically significant;the Tb.Sp of the Accordion technique group and the simple compression group were lower than the simple compression group,the difference was statistically significant;the BV,BV/TV,and Tb.Th of the Accordion technique group were higher than the simple compression group,the difference was statistically significant;the difference of the Tb.N and Tb.Sp were not significant among the Accordion technique group and the simple compression group(P>0.05);the difference of the Tb.Th was not significant among the Accordion technique group and the control group(P>0.05);the difference of the Tb.Th was not significant among the simple compression group and the control group(P>0.05).Conclusion:The method of retaining fragments of 2mm gap,scraping the outer periosteum and the local bone marrow,performing cauterization of the fracture site,and fixing with an ring external fixator can establish the model of rabbit tibial nonunion.Both simple compression technique and the Accordion technique can restarts bone healing process at nonunion site,and the threapeutic efficacy of the Accordion technique is significantly better compared with the simple compression technique.