Shoulder Ligaments

The capsule that surrounds the shoulder joint is a very strong ligament that helps to keep the ball and socket normally aligned. In most people it is very difficult to tear the ligaments of the capsule or pull the shoulder out of joint, and these injuries usually occur only when a lot of force has been applied to the shoulder or the arm -- like in a tackle football game. However, there are some people who have a capsule that is a little bit too loose, which allows the shoulder to slip partially out of joint, a process called subluxation, or completely out of joint, which is called a dislocation.

If the shoulder slips in and out of joint more than once or twice, then the joint is said to be "unstable". This condition can create a lot of problems for patients because they may not be able to do certain activities because they are afraid their shoulder will slip out of joint if they move their arm into certain positions. This is a particularly big problem for people who are "overhead athletes", like baseball pitchers and tennis players, who depend upon their shoulder to play certain sports. There is also a concern that the surface cartilage of the shoulder can be damaged if it slips in and out of joint frequently.

Shoulder instability can also occur in people who have a generalized looseness of their joints. These people are frequently very flexible and are often called "double-jointed", especially when they are school age children. A bad injury to the shoulder can also cause the shoulder to become unstable by stretching or tearing the ligaments of the shoulder away from the bone.

The younger a patient is at the time that they have their first subluxation or dislocation episode, the more likely they are to suffer from further episodes of shoulder instability. Conversely, shoulder instability is less of a problem as we grow older, because most people naturally become a little bit stiffer each year that they age.

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