The shoulder is a ball-and-socket joint comprised of three bones: the humerus, the scapula, and the clavicle. The shoulder capsule, which is made up of strong connective tissue, surrounds the joint. In frozen shoulder, the shoulder capsule thickens and bands of stiff tissue called adhesions form. While the exact cause of frozen shoulder remains unknown, there are several factors that contribute to its development. People whose shoulder has been immobilized for some time as a result of injury or surgery and people with diabetes, hyperthyroidism, Parkinson’s disease, or cardiac disease are at a higher risk for developing a frozen shoulder. The most typical symptom of frozen shoulder is the inability to move the shoulder. However, frozen shoulder actually has three distinct stages in which symptoms progress and then abate. These stages are known as freezing (pain worsens), frozen (pain recedes, but stiffness increases), and thawing (stiffness recedes). Full recovery and return to normal strength can take anywhere from 6 months to three years. Anti-inflammatory medication and physical therapy can be highly effective in reducing pain and stiffness and restoring range of motion. If non-surgical treatment does not relieve symptoms, though, surgery may be necessary. Surgery to treat a frozen shoulder often involves under-anesthesia manipulation or a shoulder arthroscopy.