"Shoulder instability" is what doctors say you have when your shoulder goes a little out of place or feels like it might. "Instability" means that the shoulder bones aren't stable--they aren't held together as tightly as they should be.
The main sign is pain in your shoulder. The pain can start suddenly or slowly. It may hit you just as you throw a ball, for example. If the injury happens suddenly, you may also feel numb all the way down your arm.
If shoulder instability comes on slowly over time, you may only notice pain at certain times. Shoulder motions like throwing may hurt, but the pain isn't as bad as the pain of a sudden injury. Your shoulder might be sore when you move it. It might feel loose in its joint. Your arm might feel weak.
No. The signs of dislocation and instability might seem the same to you--weakness and pain. However, dislocation occurs when your shoulder goes completely out of place. The shoulder ligaments are torn and can't keep the joint in place.
Shoulder instability occurs when the ligaments and muscles around it become weak. Ligaments and muscles get weak when they are stretched too much. Your shoulder muscles and ligaments might get stretched too much if you often throw a ball, hit hard with your shoulder in a football game or serve a volleyball really hard.
Your doctor will look at your shoulder, moving your arm around to find signs of instability. Your doctor may also take X-rays. The X-rays will show if your shoulder bones are in the right place. Your doctor might want you to have a magnetic resonance image (MRI) scan. An MRI lets your doctor see the bones and other parts of your shoulder in greater detail.
Treatment for shoulder instability depends on how bad your injury is and how important it is for you to have a strong shoulder. Some people need physical therapy, while others may need surgery.
Some people stop playing sports and avoid things that might hurt their shoulder again. If you don't want to give up sports or other activities, ask your doctor if you can do resistance and weight-lifting exercises to help your shoulder muscles grow stronger.
Written by familydoctor.org editorial staff