| Background Microtia is a common body surface malformation.Auricle reconstruction is not only an important clinical treatment,but also an important challenge in plastic surgery.Symmetry in the positioning and orientation of the reconstructed auricle,precision in the integrity of the auricular framework and good coverage of the skin and soft tissues are necessary to achieve a good surgical result in auricular reconstruction.Preoperative simulation,intraoperative navigation,surgical aseptic requirements,and intraoperative position restrictions restrict the treatment of microtia.Therefore,aiming at the positioning and orientation of the auricle and the carving of the auricle framework,in the first part of this study,an interactive assistant system for the treatment of microtia deformities is developed for the design and localization of the reconstructed ear in ear reconstruction.In the second part,the soft tissue coverage of expanded skin flap is discussed.In the aspect of the refinement of the subunit structure of the reconstructed ear,the third part discusses the clinical effect of tragus reconstruction by flapping hinge-cartilage.Part Ⅰ Design and surgical guidance of virtual ear based on CT data and HoloLensObjective Design and develop a virtual-reality interactive assist system for the treatment of microtia,which has visual and interactive functions,and assists in the preoperative simulation interaction,intraoperative positioning and navigation and sculpting of the auricle framework.Methods 1.Designing the 3D navigation marker set(including navigation elements and fixation elements)in the reality-virtual interactive assist system for microtia treatment so that it forms a fixation device together with the upper dentition of the volunteer,making it stable and firm.2.The auricular virtual guide is reconstructed from CT data,and the augmented reality-based technology development of the realityvirtual interactive assist system for microtia treatment software system allows it to be visualized and interactively positioned.3.The reality-virtual interactive assist system for microtia treatment can meet the reproduction and positioning guidance of the preoperative auricular virtual guide and meet the aid of auricular framework carving.Results 1.Developed and designed the reality-virtual interactive assist system for microtia treatment(HoloLens Ear-01)and its operating procedure,with the function of spatial observation,gesture interaction,and collision detection,which enables the visualization of the reconstructed virtual ear guide and the guide of the auricular framework carving,interactive positioning,and the auxiliary guidance of the reconstructed ear reconstruction surgery.2.Based on the evaluation of the registration alignment technology and display technology by the system,the manual alignment can achieve the overlap of the virtual and real models,but the alignment time is long and the automatic alignment accuracy cannot meet the clinical needs for the time being further development and system iteration is still needed to upgrade.3.The 3D navigation marker set is stable and repeatable,easy to attach and detach,no pressure damage to periodontal tissues,and meets the requirements for long intraoperative wear.Conclusions Through AR augmented reality technology,CT data and HoloLens devices,the HoloLens device has been used to develop a virtual-real interaction assist system for microtia treatment,HE-01,which can be used for preoperative design,intraoperative guidance and postoperative evaluation of auricular reconstruction.The system provides a more intuitive and rich model information for the auricular reconstruction process,enabling visual communication between the patient and the doctor interaction for the auricular design,and providing more visual information for the auricular framework carving through the visual model to assist the operator.Part Ⅱ Auricular reconstruction using an expanded postauricular flap with double pedicleObjective To investigate the clinical effect of auricle reconstruction using an expanded postauricular flap with double pedicle in the ear reconstruction.Methods From September 2016 to August 2017,the clinical data of all patients with congenital microtia treated in the Department of plastic surgery,Hospital of plastic surgery,Chinese Academy of Medical Sciences were analyzed retrospectively.The operation method:the expander was implanted in the first stage,the ear framework was covered by the retroauricular double pedicle expanded flap with free skin graft at the superior pole in the second stage,and the helix was wrapped by the retroauricular fascia.The patients were reexamined 1,6 months after operation and before the third stage operation,and the shape of the reconstructed auricle was evaluated by two doctors before the third stage operation.If there is any difference,the final evaluation will be carried out by the superior doctor,which are divided into good,medium and poor.Results A total of 46 patients(49 ears)with congenital microtia were included,including 36 males(39 ears)and 10 females(10 ears),aged 6-23 years.After operation,the blood supply was good,and the skin graft survived completely.3 ears had postoperative hematomas under the double pedicle expanded skin flap when the drainage tube was removed 5 days after operation,and recovered well after the negative pressure suction and dressing changed.During the follow-up of 6 months and 18 months,43 cases(46 ears)were evaluated well with symmetrical and clear three-dimensional structure of reconstructed auricles,uniformed color,and hidden scar behind the ear.3 cases(3 ears)were evaluated as medium.There was hematocele when the drainage tube was removed 5 days after operation,and survived completely after negative suction and dressing change.No ear framework infection and exposure were found.Conclusions The double-pedicle expanded flap has reliable blood supply,natural auricle shape,concealed scar,and small skin color difference.It is a good choice for soft tissue wrapping and covering during auricle reconstruction.Prat Ⅲ Tragus reconstruction with the hinge-shaped cartilage flap of the residual earObjective To investigate the clinical effect of reconstructed tragus with hinge-shaped cartilage flap during the third stage reconstructive surgery in patients with microtia.Methods From January 2018 to January 2019,the date of patients with unilateral microtia of residual ear type Ⅲ treated in the Department of Plastic Surgery,Plastic Surgery Hospital,Chinese Academy of Medical Sciences were analyzed retrospectively.The residual ear tissue preserved in the second stage operation was used to reconstruct the tragus during the third stage operation,and the external auditory meatus was simulated by medium-thickness skin grafting.Postoperative changes were observed in the width,height,and symmetry of the tragus.Results A total of 31 children with microtia were included,including 19 males and 12 females,aged from 6 to 14 years(mean 8 years),right ear(n=16)and left ear(n=15).Postoperative blood supply was good,and the incisions healed in one stage.The patient’s immediate postoperative tragus width and elevation height were slightly higher than the preoperative design requirements.Follow-up for 3-6 months,the width of the contralateral tragus is 1.05±0.12cm,and the reconstructed tragus width is 0.98±0.17cm,the difference was not statistically significant(P=0.328);the height of the contralateral tragus is 0.53±0.08cm,and the reconstructed tragus width is 0.55±0.08cm,the difference was not statistically significant(P=0.741).The reconstructed tragus has a strong three-dimensional sense and stable shape,and the simulated shape of the external auditory meatus is good.Patients can wear headset for activities to meet the needs of daily life.Conclusions Using residual ear cartilage to reconstruct the tragus by flapping hingecartilage can improve the three-dimensional structure of the auricle,combined with the tragus behind the concha cavity skin grafting to simulate the external ear door. |
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