The shoulder is the most flexible joint in the body, consisting of a ball called the humeral head, and shallow socket joint called the glenoid. Because the glenoid is shallow, it covers less than half of the humeral head and does not provide much structural support. Tendons, ligaments, and the soft-tissue cartilage rim around the joint (labrum) work together to hold the shoulder joint in place. Four major rotator cuff muscles (subscapularis, supraspinatus, infraspinatus and teres minor) and their associated tendons connect the upper arm bone (humerus) to the shoulder blade (scapula). The collarbone (clavicle) is located between the ribcage (sternum) and scapula, and connects the arm to the body.
The flexibility of the shoulder joint enables movement and rotation of the arms to the front, above, to the side, and behind the body. As such, the shoulder is subject to instability and injury. Studies indicate that 16 to 34% of the general population suffers from shoulder pain, with a sizeable number of these related to rotator cuff pathology. Injuries may be related to athletic activities, trauma, overuse, or the wear and tear of aging that can lead to osteoarthritis. According to the U.S. Consumer Product Safety Commission, more than 609,000 people visited U.S. hospital emergency rooms for shoulder injuries in 2014. Of these, an estimated 186,000 were strains and sprains, 109,000 were fractures, and 79,000 were dislocations.
Diagnosis and Treatment Options
Many mild shoulder injuries are treated with rest, physical therapy, and/or anti-inflammatory medications, but more severe conditions often require surgery. For many years, open surgery was the only surgical method for repairing shoulder damage. More recently, minimally invasive arthroscopic approaches have enabled surgeons to effectively treat shoulder conditions with a few small incisions, often on an outpatient basis, significantly reducing recovery time.
Diagnostic tools for shoulder injuries include medical history, a physical examination, and tests including x-rays, ultrasound, magnetic resonance imaging (MRI) and diagnostic arthroscopy. Diagnostic shoulder arthroscopy is a minimally invasive procedure in which a tiny camera is inserted into the shoulder joint in order to diagnose conditions, such as injuries to the rotator cuff, other tendon and ligament tears, arthritis, and shoulder dislocations. In many instances, treatment is offered during the same appointment. Compared to x-rays, this procedure yields a great deal of useful information about underlying pathology of the shoulder joint since the structures can be directly visualized.