Shoulder periosteal injury mostly refers to periosteal injury of shoulder joint, three months after the injury is still not good, the possible reasons are premature activity, heavy injury, traumatic arthritis and so on. 1. Premature activities: if the periosteum of the shoulder joint injury does not have sufficient rest to recover from the injury, premature activities, the injury site is constantly stimulated, will affect the recovery of periosteum injury, even after three months, there will still be shoulder pain and discomfort symptoms, you can take appropriate rest to reduce the shoulder joint activities. 2. Heavier injury: If the injury is heavier, because the violence causes damage to the blood vessels, nerves and tendons around the periosteum, because the tendons and nerves need a relatively long time to recover, even after three months, there may still be symptoms. 3. Traumatic arthritis: traumatic arthritis occurs due to the trauma to the shoulder joint, causing damage to the articular cartilage, and pain in the shoulder joint can also occur. There are more reasons why shoulder joint osteochondral injury is not well after three months, if the symptoms continue to be unrelieved, it is recommended to consult a doctor in time to clarify the cause of the disease and carry out targeted treatment.