The common causes of pain in the middle of the sternum below are as follows: First, trauma: local soft tissue injury or chest wall injury, such as external impact can occur chest wall injury, or improper sleeping position, such as often sleeping in the prone position, can cause prolonged compression of the soft tissue of the chest wall and the bed surface, so soft tissue injury can also occur, which can manifest as soreness and pain in the sternal region. Second, sternal periostitis: this is mostly caused by previous injuries to the sternum, or sternal fractures. Especially when the sternal fracture is poorly aligned and aligned, it is easy to have deformed healing, easy to have local osteophytes, which may irritate the local sternal periosteum, so it will show as pain below the sternum.