耳介形状のスプライン近似と耳介形態異常治療への適用

Abstract

On author's investigation, 76% of neonates are born with auricular deformity. This paper describes the spline approximation method of auricular shape that characterizes those deformities and it's application to the treatment. Contours of external auricular shape and inside fringe of helix are approximated by B-spline function of order four based on the ear base line. The position of control points that is coefficients of B-spline function is used as an indicator of auricular shape. Deformities are classified into 6 groups including normal ear and discriminant analysis is performed using the Mahalanobis generalized distance calculated by the distribution of control points. Also normal and abnormal rates are calculated by the component ratio of probability of belonging to the classified group. The success ratio of discriminant analysis and average of normal and abnormal rates are increased by using not only control points of external shape but also those of inside fringe of helix.The system to generate the orthosis shape for the treatment of deformities that utilizes spline approximated auricular shape is developed. Orthoses manufactured by the system were applied to patients and improved deformities within a year. The transitions of auricular shape of patients are analyzed by the position of control points and normal and abnormal rates. The result of analyses also shows that using both control points of external auricular shape and inside fringe of helix well chcracterizes the improvement of those deformities.