Studies On The Rapid Forming Of Auricle Scaffold For Microtia

Microtia is an inherent apparent malformation and disturbance which does serious harm to the patient's body and mind. Presently most of the microtias are treated by manually incising the patients' rib cartilages or with Medpor products. None of them can completely satisfy the requirement of orthopaedic operation, the former requires two operations which are more painful to the patients and the shape of the reconstructed auricle appears not lifelike, and the latter are made in standard dimensions and shapes which are not symmetrical to the normal auricles of the patients' and not customized service.In this dissertation, the bio-manufacturing technology is adopted, designing the digital model of the abnormal ear with the CT data of the normal side is brought forward and realized to drive the rapid forming machine based on the discrete/ deposit forming principle. The biocompatible polymer of adequate mechanical performance is chosen for making the implantable auricle scaffold to replace incising the ribs for the reconstruction of microtia.In consideration of the asymmetry of skull development, the reengineering and design method of auricle cartilage based on asymmetric skull is brought forward to insure the concerted relation between both auricles.Extra high molecular weight polyethylene, high density polyethylene and polyurethane are extruded apart and together, and the materials are used in technical tests and analyzed with instruments. Polymers are studied according to the requirements of the final auricle scaffolds and the process, and the polymer of perfect biocompatibility, safety in process and nice feel is selected as material for making auricle cartilage scaffolds.In allusion to the difficulty in feeding flexible material with frictional conveying machine of MEM, directly granule feeding machine is brought forward and realized in the paper. By analyzing the vibration, the design of the machine is further improved to feed the particles steadily and equably. The realization of the feeding machine of granule greatly broadens the material scope of MEM process, shortens the processing chain of material preparation, fabricating and reduces the possibility of pollution.A desktop biomaterial rapid forming system is developed, also the circuits of NC, material feeding and extruding are designed systematically. A software system is developed for the rapid forming of reengineered complex anomalistic surface, the entire forming of auricle cartilage is realized. A new worktable is designed which greatly improves the cleanliness of forming, and avoids the conglutination wastage of foam table. The control of porosity and connectivity of the scaffold is realized by alternating the combination of contour, filling and control of the scanning direction which improves the structural biocompatibility of the implant and early concrescence through the technology.The auricle scaffolds made of TPU are tested for their cell toxicity, tissue compatibility and with the preclinical animal tests, also the applicability of the material and the feasibility of the technology are tested. The anticipant goal is attained for having developed the biocompatible customized auricle scaffold with rapid forming technology.