It is a painful condition of the chest wall. Cartilages attach the ribs to the breastbone (sternum) and the sternum to the collarbones (clavicles). The joints between ribs and the cartilages is called the costochondral joints. It is not a serious condition it affects more than one rib. Costochondritis is an inflammation of the junctions in which upper ribs join with the cartilage that hold the breastbone. It affects females more than males.
Source: https://www.herbal-care-products.com/blog/11-natural-remedies-for-costochondritis/