The most movable joint in the body, the shoulder is also one of the most potentially unstable joints. As a result, it is the site of many common problems. They include sprains, strains, dislocations, separations, tendinitis, bursitis, torn rotator cuffs, frozen shoulder, fractures, and arthritis.

According to the Centers for Disease Control and Prevention, about 13.7 million people in the United States sought medical care in 2003 for shoulder problems.