| Background Congenital microtia is the most common malformation following cleft lip and palate, it is a kind of congenital malformation characterized by unknown etiology, with congenital dysplasia of auricle, often accompanied by ankylotia, middle ear and maxillofacial malformation, it's incidence is 1/7000. Microtia can be divided into three type in clinical according to the degree of auricle defect clinically. Up to now, three clinical techniques commonly used in microtia reconstruction including Brent's technique, Nagata's technique and expander technique all based on Tanzer's technique. According to the existing clinical microtia classification and surgical techniques, there are defects including no utilization of epibiotic ear cartilage, tedious operation, discrepancy between reconstructed auricle and contralateral auricle etc.Purpose By way of the study on auricular cartilage constructed by three-dimensional biodegradable framework combined with autologous cartilage granules, to observe the form and stability of osteochondral framework, the combination of cartilage granules and the H-E staining cartilage cells morphology microscopically, we hope to provide some new ideas of microtia reconstruction techniques which will be simple rapid, epibiotic ear cartilage utilization and have less complications.Methods Experiments were performed on 8 male New Zealand White rabbits (all provide by Qinglongshan animal farm),2.8-3.2 Kg weight. Subjects were randomly divided into two groups. A group and B group,4 rabbits in each group, all three-dimensional biodegradable framework combined with autologous cartilage granules. We choose poly(p-dioxanone)(PPDO) as the experimental biodegradable framework material(PPDO and three-dimensional printing technology are provided by the Tianjin Weishen technology co., LTD.). PPDO has many features such as safe and reliable, not easy to cause deformation and takes a long time to degrade in the body. It has already been widely applied in clinical. Internal biodegradable framework size is about 2.8 mL. The experiment steps are as follows,1.1% pentobarbital intravenous anesthesia; 2. Take out the corresponding volume of cartilage from the right ear of the rabbit, closure and bandage up the wound; 3. The ear cartilage should be trimmed into granules(size:1mm×1mm), the granules should be washed by physiological saline then uniformly packed into the biodegradable auricle framework; 4. We make the mixture covered by sarcolemma subcutaneous, place negative pressure drainage, the rabbit should be immobilized after operation. Observation methods are as follows, We termly observe the form and stability of the auricle, the degradation of the framework and the possible complications. We take out the cartilage granules and biodegradable framework in different times after the operation of three experimental groups (A group:one month; B group: three months). Obersve the form and stability of ear cartilage, the combination of cartilage granules, the degradation of the framework and H-E staining cartilage cells morphology microscopically.Results It's showed that the reconstruction auricle possesses good shape shortly after surgery while the form of framework have a good form and well stability. At the same time, the degradation of framework is not significant. One month later, the framework is gradually degraded and the general structure of auricle preliminary presence and the fine structure gradually disappear. At the sametime, rabbit ear cartilage is survived well while cartilage granules are close combined by fibrous connective tissue.Conclusion This experiment proved the desirable biocompatibility between autologous cartilage granules and PPDO framework, which offers support to the follow-up work. We also found that there are some problems and deficiencies of the prior theoretical and experimental methods and materials. It means that we still need to explore new methods and improve our experiment. We hope that this experiment is useful for clinical microtia surgery program. |
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