A 13-year-old boy’s sunken ribs may be caused by developmental deformities and rib fractures. 1. Developmental deformities: sunken ribs may be caused by calcium deficiency and vitamin D deficiency, resulting in rib deformities, which are manifested as sunken ribs. If there is a lack of these nutrients, you should supplement these nutrients and eat food with high calcium content, such as beans, milk, shrimp, sesame paste, etc. 2. Rib fracture: 13-year-old boy rib depression may be the manifestation of rib fracture, if the ribs have been traumatized, may be due to this reason. The 13-year-old boy with depressed ribs should actively seek medical attention to avoid adverse results, and should be treated according to specifications for the condition to prevent the condition from continuing to develop.