The shoulder is an inherently unstable joint and depends on the surrounding muscles, capsule and ligaments for support and stability. These structures may be congenitally loose or damaged as a result of injury.
This can lead to excessive movement of the end of the arm bone in the socket, or if due to a high-energy injury (e.g., fall or tackle during sports), a dislocation of the joint. The latter injury may be associated with damage to the nerves and blood vessels of the upper limb, and require urgent medical attention.
