Shoulder instability occurs when the shoulder joint, also known as the humeral head, moves partially or completely from the from the shoulder socket, known as the glenoid. This is usually as a result of detaching, tearing or stretching of the ligaments or the lining of the shoulder joint. Common causes of a shoulder instability include overuse of the shoulder, and injuries caused by falling, diving headfirst, collision and seizures.

Some of the common symptoms of shoulder instability include severe pain, inability to move the shoulder, sensation of a pop in the shoulder, and difficulty in lifting the arm overhead among others. Treatment for patients with shoulder instability includes non-surgical and conservative methods including physical therapy, possible bracing, activity modification and the use of NSAIDS (non-steroidal anti-inflammatory drugs) to control any discomfort and swelling. However, in severe cases, surgery may be recommended to improve the stability of the shoulder and return full range of motion.