Asymmetry of the left and right ribs with a slightly raised left rib cage may be due to old injuries, bony deformities, thoracic diseases, dysplasia and other reasons. 1. Old injury: If there is an old rib fracture on the left side with overgrowth of the bone crust, which causes the collapse of the thorax, it will cause rib asymmetry. 2. Bone deformity: If you have scoliosis or rickets and other bone deformity diseases, it may cause the above situation. 3. Thoracic diseases: if you suffer from pleural effusion and other internal thoracic diseases, it can also cause rib asymmetry. 4. Poor development: If there is a lack of calcium or osteoporosis during adolescent development, as well as other congenital factors, it may cause deformity of the thorax. It should be noted that if there is a serious thoracic deformity, the development of lung tissue may be affected, resulting in severe respiratory insufficiency or cardiac insufficiency, it is recommended to go to the hospital for a clear diagnosis and active treatment.