背景：小耳畸形，作为一种常见的体表器官异常，其修复与重建在整形外科临床中占据着重要地位，同时也是整形外科面临的关键挑战。要取得良好的耳廓再造手术效果，关键是准确地定位耳廓并保持其正确的轴向，确保再造耳廓框架结构的完整，并适当地覆盖皮肤和软组织。治疗小耳畸形时，术前的设计、再造耳定位、手术中的肋软骨支架雕刻、肋软骨支架放置和固定等多个方面都需要尽可能地精准。因此，在本研究的第一部分，我们专门设计并开发了一种耳廓3D数字导板辅助耳再造系统Hololen ear 01（HE01），旨在耳廓再造的术前设计与术中耳支架雕刻及定位中发挥作用，并验证了其可行性。第二部分利用HE01系统辅助单侧耳再造并进行临床对照研究，探究HE01辅助下耳再造的手术效果。

目的：1.建立基于患者头面部三维数据与HoloLens现实增强头戴式外设的耳再造虚拟与现实结合辅助系统（HoloLens Ear 01，HE01），并验证该系统在耳廓再造手术中的应用可行性。2.利用HE01辅助系统生成供术者参考的理想的耳廓三维立体轮廓和位置，从而提高再造耳廓的形态和对称度，并对比应用HE01辅助系统和不应用HE01辅助系统下再造耳的效果。

方法：1.于2021年8-9月在中国医学科学院整形外科医院招募的3名志愿者和6名小耳畸形患者为研究对象，运用3D slicer、Meshlab和Blender软件构建虚拟耳廓三维模型，基于HoloLens和导航套装构建小耳畸形治疗虚实交互辅助系统HE01，通过志愿者重复试验评价HE01的配准精准度、跟踪延迟度及显示效果，明确操作流程并验证HE01应用于耳廓再造术的可行性。 2.选取2022年1月至2022年11月在中国医学科学院整形外科医院行单侧小耳畸形耳再造术患者60例(男42例，女18例)，随机分为实验组（HE01辅助组，n=30），对照组（非HE01辅助组，n=30）两组。实验组利用HE01系统生成虚拟耳廓3D数字导板。将3D数字导板应用于术前设计和术中辅助耳支架雕刻和定位。对照组采用平面耳模片辅助术前定位和指导肋软骨支架的雕刻。两组均采用八大处扩张法进行耳再造手术。6个月后观察随访。记录再造耳与健侧耳之间和长、宽、高、周长及位移的差值。利用卡方检验和配对t检验计算再造耳与健侧耳的差别。

结果：1.成功构建HE01辅助系统并明确操作流程。志愿者实验显示不同角度下配准精准度高，跟踪延迟度低（最高1.4s，最低1.1s），3D耳廓导板银色显示最令人满意。小耳畸形患者实验显示HE01可应用于耳廓再造术，导航标记装置佩戴无明显并发症，具有可重复性和稳固性。2.在临床对照研究中，实验组与对照组患者平均年龄及健侧耳长、宽、高和周长对比均无统计学差异（p＞0.05）。实验组与对照组再造耳与健侧耳长、宽、高和周长对比均无统计学差异（p＞0.05）。实验组与对照组再造耳与健侧耳长、宽、高和周长的差值对比均无统计学差异（p＞0.05），再造耳与健侧耳长、宽、高差值的平均值（ΔL+ΔW+ΔH/3），实验组显著低于对照组（p＜0.05）。实验组再造耳的位移差值显著低于对照组（p＜0.05）。采用HE01系统辅助后再造的耳廓与健侧耳的整体差距更小，对称度更好。

结论：1.本研究完成了基于导航套装、CT数据与HoloLens的增强现实辅助耳廓再造系统HE01的构建，HE01具有良好的配准精准度、追踪速度和显示效果，可应用于临床。2.HE01辅助系统可以在耳廓再造手术中反映耳廓的三维结构和大小，且有助于再造耳的定位。相较于不使用HE01辅助,使用HE01辅助耳再造可以缩小与对侧耳的形状差异并提高对称度。

Abstract

Background：Microtia is a prevalent congenital deformity impacting clinical medicine and reconstructive surgery, posing significant challenges in plastic surgery. Achieving superior outcomes in auricle reconstruction hinges on precise auricle positioning and orientation, maintaining the structural integrity of the auricle framework, and ensuring adequate skin and soft tissue coverage. The treatment of microtia involves stringent measures across various phases, such as preoperative simulation and positioning, intraoperative guidance and navigation, adherence to surgical sterility, and specific intraoperative positional constraints. Given the auricle's symmetric position on the head, its treatment distinctly differs from other surgical procedures. This study introduces two main components: the first involves the development of the Hololen ear 01 (HE01), a 3D digital guide system for auricle reconstruction designed to aid in preoperative planning and intraoperative sculpting and positioning, with an assessment of its practicality. The second component evaluates the use of the HE01 system in unilateral ear reconstruction through a clinical control study, examining symmetry and the success rate of reconstructions assisted by HE01. Additionally, the third part evaluates the clinical effectiveness of local injections of a drug mixture in reducing postoperative chest pain in patients undergoing ear reconstruction with rib cartilage.

Objective: 1.An ideal 3D cartilage framework and accurate anatomical location are the most important factors to carry out a satisfactory reconstruction of the ear. To streamline this process, we developed an augmented reality assistance system, HoloLens Ear Image Guidance, which is based on CT data, tailor-made navigation kits to guide reconstruction, data processing software, and HoloLens hardware. The objective of this study is to verify its feasibility in a clinical setting. 2.Using the HE01 system, an ideal three-dimensional contour and position of the reconstructed ear is generated for the surgeon to improving the shape and symmetry of the reconstructed ear. The effects of reconstructing the ear using the HE01 assistance system and without using the HE01 assistance system are compared during a randomized control trail.

Methods: 1.Three healthy volunteers and six patients with unilateral microtia were recruited.This study first validated our system in healthy controls, then extrapolated data to test on patients with microtia. First, reconstructive navigation kits were made using 3d printing. CT data were collected for the head and neck and imported into the HoloLens Ear Image Guidance Application to generate a personalized 3-D virtual ear image.  Volunteers then wore the navigation kits while researchers observed them through the HoloLens to check accuracy, track delay, and view the ear image guidance. 2.A total of 60 patients (42 males and 18 females) who underwent unilateral microtia ear reconstruction in our unit from January 2022 to November 2022 were selected and randomly divided into experimental group (HE01 group, n=30) and control group (non-HE01 group, n=30). The experimental group used HE01 system to generate 3D digital guide of virtual auricle. The 3D digital guide was applied to preoperative design and intraoperative ear support engraving and positioning. In the control group, a planar ear mold was used to assist preoperative localization and guide the carving of the costocartilage scaffold. The two groups were treated with Badachu methods for ear reconstruction. Follow-up was observed 6 months later. The differences of length, width, height, circumference and displacement between the reconstructed ear and the normal pleural ear were recorded. Chi-square test and paired T-test were used to calculate the difference between reconstructed ear and normal ear.

Results: 1. The tracking delay was less than 1.26 s （±0.09 s), the display effect was good, and surgeons did not report discomfort or dizziness while wearing the HoloLens. Volunteers did not report any pain from holding the navigation reference in their mouth during the test. Following validation, the HoloLens assisted procedures were not associated with surgeon discomfort or dizziness. No complications were noted in patients patients including injury to the oral mucosa. 2. There were no significant differences in the mean age and the length, width, height and circumference of healthy lateral ear between the experimental group and the control group (p > 0.05). There were no significant differences in the length, width, height and circumference of reconstructed ear and healthy pleural ear between the experimental group and the control group (p > 0.05). There were no significant differences in the length, width, height and circumference of the reconstructed ear and the healthy pleural ear between the experimental group and the control group (p > 0.05). The average difference of the reconstructed ear and the healthy pleural ear was significantly lower in the experimental group than in the control group (p < 0.05). The displacement difference of the reconstructed ear in the experimental group was significantly lower than that in the control group (p < 0.05). With the aid of HE01 system, the overall gap between the reconstructed auricle and the healthy ear is smaller and the symmetry is better.

Conclusions: 1.The HoloLens Ear Image Guidance initially met clinical demands in registration accuracy, tracking speed and subjective user experience, which can be used as the basis for continual software improvements and clinical application. 2.The HE01 auxiliary system can reflect the three-dimensional structure and size of the auricle during auricle reconstruction, and help to locate the reconstructed ear. Compared with the non-HE01 assisted ear reconstruction, the use of HE01 assisted ear reconstruction can reduce the shape difference between the ear and the opposite ear and improve the symmetry.