Abstract
Skin necrosis is the most common complication in total auricular reconstruction, which is mainly induced by vascular compromise and local stress concentration of the overlying skin. Previous studies generally emphasized the increase in the skin flap blood supply, while few reports considered the mechanical factors. However, skin injury is inevitable due to uneasily altered loads generated by the intraoperative continuous negative suction and uneven cartilage framework structure. Herein, this study aims to attain the stable design protocol of the ear cartilage framework to decrease mechanical damage and the incidence of skin necrosis. Finite element analysis was initially utilized to simulate the reconstructive process while the shape optimization technique was then adopted to optimize the three-pretested shape of the hollows inside the scapha and fossa triangularis under negative suction pressure. Finally, the optimal results would be output automatically to meet clinical requirement. Guided by the results of FE-based shape optimization, the optimum framework with the smallest holes inside the scapha and fossa triangularis was derived. Subsequent finite element analysis results also demonstrated the displacement and stress of the post-optimized model were declined 64.9 and 40.1%, respectively. The following clinical study was performed to reveal that this new design reported lower rates of skin necrosis decrease to 5.08%, as well as the cartilage disclosure decreased sharply from 14.2 to 3.39% compared to the conventional method. Both the biomechanical analysis and the clinical study confirmed that the novel design framework could effectively reduce the rates of skin necrosis, which shows important clinical significance for protecting against skin necrosis.
Highlights
Microtia is a congenital deformity characterized by the underdevelopment of the external ear, with an estimated annual incidence of up to 30.6 cases per 100,000 population in China (Deng et al, 2016)
Finite element analysis was initially utilized to simulate the reconstructive process while the shape optimization technique was adopted to optimize the threepretested shape of the hollows inside the scapha and fossa triangularis under negative suction pressure
Total auricular reconstruction is a challenging procedure that is generally performed in three stages, while the primary phase is the key to achieve the optimal outcome (Yamada, 2018)
Summary
Microtia is a congenital deformity characterized by the underdevelopment of the external ear, with an estimated annual incidence of up to 30.6 cases per 100,000 population in China (Deng et al, 2016). Auricular reconstruction continued to be the most challenging technique among plastic surgery, with the main difficulties of framework fabrication and emergence of various complications (Rocke et al, 2014; Frenzel, 2015). The most accepted protocol among surgeons worldwide is that the Nagata technique and its modifications typically used the ipsilateral rib cartilage to form the framework in the first-stage surgery (Bly et al, 2016). Skin necrosis is one of the most common complications, which mainly occurred after the first-stage modification. Previous studies had discovered that vascular compromise and local stress concentration of the overlying skin were the two main contributors to skin ischemia, even skin necrosis (Anghinoni et al, 2015; Cugno and Bulstrode, 2019). Much evidence focused on how to provide an adequate blood supply of the skin flap, but only few considered the mechanical issues (Márquez-Gutiérrez et al, 2017; Olcott et al, 2019)
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