Yau Amy Y Y, Manuel Cyrus, Hussain Syed F, Protsenko Dmitry E, Wong Brian J F
Department of Otolaryngology-Head and Neck Surgery, University of California, Irvine.
Beckman Laser Institute, University of California, Irvine.
JAMA Facial Plast Surg. 2014 Jul-Aug;16(4):245-52. doi: 10.1001/jamafacial.2014.85.
Electromechanical reshaping (EMR) is a low-cost, needle-based, and simple means to shape cartilage tissue without the use of scalpels, sutures, or heat that can potentially be used in an outpatient setting to perform otoplasty.
To demonstrate that EMR can alter the shape of intact pinnae in an in vivo animal model and to show that the amount of shape change and the limited cell injury are proportional to the dosimetry.
DESIGN, SETTING, AND SPECIMENS: In an academic research setting, intact ears of 18 New Zealand white rabbits underwent EMR using 6 different dosimetry parameters (4 V for 5 minutes, 4 V for 4 minutes, 5 V for 3 minutes, 5 V for 4 minutes, 6 V for 2 minutes, and 6 V for 3 minutes). A custom acrylic jig with 2 rows of platinum needle electrodes was used to bend ears at the middle of the pinna and to perform EMR. Treatment was repeated twice per pinna, in proximal and distal locations. Control pinnae were not subjected to current application when being bent and perforated within the jig. Pinnae were splinted for 3 months along the region of the bend using soft silicon sheeting and a cotton bolster.
The ears were harvested the day after splints were removed and before euthanasia. Photographs of ears were obtained, and bend angles were measured. Tissue was sectioned for histologic examination and confocal microscopy to assess changes to microscopic structure and cellular viability.
Treated pinnae were bent more and retained shape better than control pinnae. The mean (SD) bend angles in the 7 dosimetry groups were 55° (35°) for the control, 60° (15°) for 4 V for 4 minutes, 118° (15°) for 4 V for 5 minutes, 88° (26°) for 5 V for 3 minutes, 80° (17°) for 5 V for 4 minutes, 117° (21°) for 6 V for 2 minutes, and 125° (18°) for 6 V for 3 minutes. Shape change was proportional to electrical charge transfer, which increased with voltage and application time. Hematoxylin-eosin staining of the pinnae identified localized areas of cell injury and fibrosis in the cartilage and in the surrounding soft tissue where the needle electrodes were inserted. This circumferential zone of injury (range, 1.5-2.5 mm) corresponded to dead cells on cell viability assay, and the diameter of this region increased with total electrical charge transfer to a maximum of 2.5 mm at 6 V for 3 minutes.
Electromechanical reshaping produced shape change in intact pinnae of rabbits in this expanded in vivo study. A short application of 4 to 6 V can achieve adequate reshaping of the pinnae. Tissue injury around the electrodes increases with the amount of total current transferred into the tissue and is modest in spatial distribution. This study is a critical step toward evaluation of EMR in clinical trials.
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机电重塑（EMR）是一种低成本、基于针且操作简单的方法，可在不使用手术刀、缝线或热能的情况下对软骨组织进行塑形，有望用于门诊环境下的耳廓整形手术。
在体内动物模型中证明EMR可改变完整耳廓的形状，并表明形状改变量和有限的细胞损伤与剂量测定成正比。
设计、场所和标本：在学术研究环境中，对18只新西兰白兔的完整耳朵使用6种不同的剂量测定参数进行EMR（4伏持续5分钟、4伏持续4分钟、5伏持续3分钟、5伏持续4分钟、6伏持续2分钟、6伏持续3分钟）。使用带有两排铂针电极的定制丙烯酸夹具在耳廓中部弯曲耳朵并进行EMR。每只耳廓在近端和远端位置重复治疗两次。对照耳廓在夹具内弯曲和穿孔时不施加电流。使用软硅胶片和棉垫沿弯曲区域对耳廓进行3个月的固定。
在拆除固定物后且安乐死之前的当天采集耳朵。获取耳朵的照片并测量弯曲角度。对组织进行切片以进行组织学检查和共聚焦显微镜检查，以评估微观结构和细胞活力的变化。
与对照耳廓相比，经治疗的耳廓弯曲程度更大且形状保持更好。7个剂量测定组的平均（标准差）弯曲角度分别为：对照组55°（35°）、4伏持续4分钟组60°（15°）、4伏持续5分钟组118°（15°）、5伏持续3分钟组88°（26°）、5伏持续4分钟组80°（17°）、6伏持续2分钟组117°（21°）、6伏持续3分钟组125°（18°）。形状改变与电荷转移成正比，电荷转移随电压和施加时间增加。耳廓的苏木精 - 伊红染色显示，在插入针电极的软骨和周围软组织中存在局部细胞损伤和纤维化区域。这个损伤的圆周区域（范围为1.5 - 2.5毫米）在细胞活力测定中对应于死亡细胞，并且该区域的直径随着总电荷转移增加，在6伏持续3分钟时最大达到2.5毫米。
在这项扩展的体内研究中，机电重塑使兔子完整耳廓产生了形状改变。短时间施加4至6伏电压可实现耳廓的充分塑形。电极周围的组织损伤随着转移到组织中的总电流量增加，且在空间分布上较为适度。这项研究是迈向在临床试验中评估EMR的关键一步。
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