| Autogenous costal cartilage is the first selection as the frameworks material in ear reconstruction operation. The auricular frameworks are three-dimensional and require some certain force to maintain its stability. So, the biomechanical property of the rib cartilage is crucial in maintaining good appearance and good postoperative result of the reconstructed ear. With increasing age of the rib cartilage, the histology characters changes accompanying the alternation of the mechanical properties. Therefore, successful ear reconstruction is closely related to suitable time for operation. At present, surgeons pay more attention to the psychology, the volume of rib cartilage or the size of the reconstructed ears in the option of time for ear reconstructed, they give less consideration to the histological and biomechanical properties of the rib cartilage. Several studies have investigated the biomechanical properties of cartilage, however, they were mainly confined to joint cartilage or pathological rib cartilage and little is known on the age-related mechanical and histological behavior of the health human coastal cartilage yet. The aim of this study was to analyze the influence of donor age on biomechanical and histological characteristics of human rib cartilage and to provide theoretical reference in option of operative time when the rib cartilage is used as framework material in ear reconstruction surgery.This study includes age-related biomechanical and histological experiments. Human costal cartilages were harvested from 25 female and 45 male donors of 5-25 years old after auricular reconstructive surgery. The specimens were divided into six groups: children (5~10years), adolescent (11~17years) and adult (18~25years), respectively in males and females. Tensile strength, stress-strain relationship, stress relaxation and creep were tested by using a material testing machine and aimed at investigating the influence of age on biomechanical of human rib cartilage. The general pathological staining, immunizing histochemical staining and typeâ…¡collagen protein quantitative analysis were done to find age dependency exists in histological structure of human rib cartilage. In addition, the comparison and analysis between the biomechanical and histological properties were discussed.The current study confirms that the biomechanical properties and histological structure of costal cartilage are donor age and gender related. The children group has the highest tensile strengths ( p <0.05) in both male and male+female groups. The ossification of the male group, which relaxed and creep more than that of the female group in all three age groups ( p <0.05), occurred later than the female group. The intensity of typeâ…¡collagen weaken with the growing of the donor age.The results indicated in this study can partly explain the clinical phenomenal that using the adolescent costal cartilage caused a bigger distortion and adult costal cartilage were sculptured difficultly during the auricular reconstruction operation. Moreover, the mechanical properties of the human costal cartilage indicated in the present study can be used as a reference in the design and fabrication of rib cartilage-based implants. Furthermore these data can be used for evaluating the mechanical properties of the tissue engineered samples, which should have the similar mechanical properties to those of the native tissues. The functions of mechanical properties of costal cartilage can be used as referenced constitutive equations of mechanical properties of corresponding age costal cartilage.According to current study, consideration in all comprehensive factors, it is suggested to operate in childhood when using autogenous rib cartilage as framework material in ear reconstruction. |
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