Auricular reconstruction is one of the most troublesome and complicated operations. Presently, autogenous costal cartilage is the first choice for reconstructing the auricular framework; therefore, it is important to understand the biomechanical properties of rib cartilage for sustaining the outline form to achieve a satisfactory postoperative effect.
Ninety human costal cartilages of the seventh middle section were obtained after ear reconstruction from tissues left over after surgery. The tensile strength test, the stress and strain test, and the creep and stress relaxation test were performed in vitro using an Instron materials testing machine (type 4302; Instron Ltd, High Wycombe, United Kingdom). The specimens were divided into six different groups as follows: children (5 to 10 years old), marked A in girls and A1 in boys; adolescents (11 to 17 years old), marked B in girls and B1 in boys; and adults (18 to 29 years old), marked C in women and C1 in men. Each group had 15 male and female subjects.
In auricular reconstruction, the curved auricular frame is a multilayer, three-dimensional stereo structure; it needs mechanical strength to sustain its stability. Its satisfactory mechanical properties help the cartilage frame to resist the absorption and deformation, thereby ensuring the further effect of surgery. Two aspects are considered—psychology and physiology—when making the choice regarding the timing of auricular reconstruction surgery. From the standpoint of psychology, the sooner the better, to avoid unhealthy psychological effects on the child patient. Zhuang et al.,1 Brent,2 and Fukuda3 believe the operation should be performed before the patient is 6 or 7 years of age. From the standpoint of physiology, the timing depends on whether the size of the auricle reaches or approximates that of the adult size and whether the size of the costal cartilage satisfies the need for a curved frame. Tanino and Miyasaka4 pointed out that a curved auricular frame needs a lot cartilage tissue, so 8 to 10 years is the ideal age. At the same time, Qi keming et al.5 had conducted a study that included 1057 different-age, normal Chinese people through measuring their auricular size to demonstrate that in children of school age and younger, the auricle is 0.9 cm smaller than in adults. Therefore, they pointed out that the operation should be performed after 13 years of age.
The results of this study show that the tensile strength in the group consisting of children was significantly higher than that in the adolescent and adult groups in both male and female groups. This could be because of the different collagen structure that exists in children. The stress and strain test and the creep and stress relaxation test show that the group of children had cartilage that was the most flexible and the most resistant to deformation. This phenomenon could be explained by cartilage calcification and ossification, which increased the stiffness in the adult groups. The calcification and the stiffness of cartilage increase with age; thus, cartilage is not suitable for use as a frame material for auricular reconstruction after the age of 29 years.
In summary, integrating psychological, physiologic, and biomechanical properties, our results indicate that auricular reconstruction surgery using costal cartilage should be performed during childhood to take advantage of the best biomechanical properties.
Qing-hua Yang, M.D.
Yu-peng Song, M.D.
Hai-yue Jiang, M.D.
Le-ren He, M.D.
Shu-jie Wang, M.D.
Plastic Surgery Hospital
Peking Union Medical College
Chinese Academy of Medical Sciences
This work was supported by the Plastic Surgery Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences. The authors thank the patients and their families for their kind cooperation with this research.
1.Zhuang HX, Jiang HY, Pan B, et al. Ear reconstruction using soft tissue expander in the treatment of congenital microtia (in Chinese). Zhonghua Zheng Xing Wai Ke Za Zhi
2.Brent B. Microtia repair with rib cartilage grafts: A review of personal experience with 1000 cases. Clin Plast Surg
3.Fukuda O. Long-term evaluation of modified Tanzer ear reconstruction Clin Plast Surg
4.Tanino R, Miyasaka M. Reconstruction of microtia using tissue expander. Clin Plast Surg
5.Qi keming, Bo jie, Xiong bin, et al. The research about auricular development in Chinese and the choice of timing for auricular reconstruction (in Chinese). Zhonghua Zheng Xing Wai Ke Za Zhi
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