There are two types of deformity, type I: the rib cartilage on both sides of the sternum is deeply depressed, the sternum as a whole is raised forward, the saber prominence points to the back, the longitudinal section of the sternum is bow-shaped, the lower part of the sternum is the most obvious raised. Type II: The sternal stalk, upper part of the sternal body and upper part of the rib cartilage protrude forward, the lower part of the sternal body is depressed backward, and the rib cartilage on both sides of the connected sternum is also depressed inwardly, while the lower part of the sternal body and the saber protrusion are bent forward, and the longitudinal section of the sternum is roughly “Z” shaped, which is also called the subtype of funnel chest. In the past, it was believed that children with precordial disease combined with chicken chest is due to the children often struggle to breathe, and repeated lung infections caused by respiratory distress, children for abdominal breathing, relying on the diaphragm lifting movement, and the chest wall is thin, the rib cage is soft, long-term diaphragmatic pulling effect of the lower thorax, the 4th to 8th rib diaphragm attachment sunken into a groove, called Ha’s groove, the sternum protrudes into the chicken chest, calcium deficiency caused by rickets also plays a role. However, children with prediabetes are often prone to respiratory tract infections, but it is not common to suffer from chicken chest. Therefore, it is believed that chicken chest is genetically related to the development of prediabetes, and there are also theories of rib overgrowth and abnormal development of the diaphragm attachment site.