Funnel chest (Pectus excavatum), also known as sternal depression deformity, is a common deformity of the sternum. 1977 Ravitch reported the incidence of 1/300~1/400 in living infants, more common in males than females, with a male to female ratio of 4:1. It is characterized by a downward dorsal tilt from the sternal stalk, with the sternum and ribs depressed inward and backward in a navicular or funnel shape. The sternum is most deeply depressed at the junction of the sternal body and the sternum is sometimes asymmetrical on both sides and rotated to the right. Etiology】 The etiology of funnel chest is still inconclusive. Funnel chest can be part of some syndromes, such as Marfan’s syndrome, Prune-belly syndrome, and Pierre-Robin syndrome. Funnel chest can exist alone, and this type is more common. There are several theories of its etiology as follows: 1 , shortening of the central tendon of the diaphragm: Although the theory of modification can visually explain the formation of the funnel chest, the shortened central tendon was not found during surgery, and the imaging findings do not support it and are not consistent with the clinical presentation, so the proponents of this theory are rapidly decreasing. 2 , Respiratory obstruction: If there is an obstruction of the respiratory tract, a prolonged period of forceful inspiration due to inspiratory dyspnea will result in the formation of a funnel chest. However, most children with respiratory obstruction do not have funnel chest, and children with funnel chest do not necessarily have respiratory obstruction, which means that respiratory obstruction is only a causative factor for the formation of funnel chest. 3 . Partial anterior diaphragm muscle fibrosis: Brodkin proposed in 1953, but it cannot explain some clinical manifestations and is only a partial cause of the formation of funnel chest. 4 . Bone and rib cartilage dysplasia: Although no direct evidence of rib cartilage and sternum dysplasia in children with funnel chest has been obtained, abnormal biochemical tests of rib cartilage have been found, with abnormalities observed under light microscopy and mutations in the amino acid sequence of cartilage collagen. 5, connective tissue abnormalities: because funnel chest is often combined with diseases of the skeletal muscle system, especially recently found that the skin fibroblasts of children with funnel chest have abnormal collagen synthesis, suggesting the possibility of systemic connective tissue diseases in children with funnel chest. 6, funnel chest has a certain genetic factor: 11%~37% of children have a family history. Funnel chest is associated with decreased immune function. The argument that funnel chest is caused by rickets is not valid. Clinical manifestations] Since the funnel chest deformity is gradually aggravated after birth, it is not very obvious in infancy. Younger children have fewer conscious symptoms, while older children may have respiratory and circulatory disorders, but those with milder deformities may have no obvious symptoms. Most infants and children with funnel chest are asymptomatic. The respiratory effects are a decrease in lung volume, an increase in residual air volume, and recurrent symptoms of respiratory infections, especially shortness of breath during activity. Circulatory disorders are symptoms of dyspnea, frequent pulse, and palpitations. Signs are thoracic deformity with anterior neck flexion, mild hunchback, and protruding abdomen. Special attention should be paid to the psychological disorder of older children due to thoracic deformity, becoming introverted, and in severe cases, mental depression leading to mental disorders. Diagnosis】 The diagnosis of this disease can be made by examination of appearance. That is, the sternal ribs are sunken, the abdomen is convex, the neck and shoulders are tilted forward, the back is hunched, and the older children may have scoliosis. However, the degree of funnel chest, cardiopulmonary function and the psychological and mental status of the child need to be evaluated comprehensively. 1, the degree of funnel chest: (1) the volume of the funnel chest: the child is supine and the amount of water injected into the funnel area is used to express. (2) funnel chest index: FI = (a b c / A.B.C) a: the longitudinal diameter of the depression; b: the transverse diameter of the depression; c: the depth of the depression: A: the length of the sternum; B: the transverse diameter of the thorax; C: the shortest distance from the angle of the sternum to the vertebral body. FI 〉 0.3 for severe; FI < 0.2 for mild; FI: 0.2 ~ 0.3 for moderate. (3) thoracic-spinal gap: the distance between the sternum and the spine L. L〉7cm for mild, L=5~7cm for moderate, L〈5cm for severe. 2.Chest radiograph: orthopantomograph shows flat ribs, with the front ribs tilted sharply downward toward the front; lateral radiograph shows obvious posterior depression of the lower end of the sternum; the spine has lateral curvature, the heart shadow is displaced to the left, and the diaphragm position is normal. 3. Pulmonary function: the exertional expiratory volume and maximum ventilation volume were significantly reduced. However, children cannot cooperate well with this examination. 4.EKG: suggests heart displacement. 5.CT: more accurate understanding of the degree of malformation. It can clearly show the improvement of preoperative and postoperative malformation, and can judge the effect of surgery.