The shoulder joint is a “ball & socket” joint made up of the upper part of the arm bone (termed the humeral head) that forms a ball shape and fits into a shallow socket (termed the glenoid), on the side of the shoulder blade. The surfaces of the humeral head and the glenoid are covered by a smooth, Teflon-like tissue called the articular cartilage. This tissue layer allows the ends of the bones to glide smoothly against one another during shoulder motion.
Osteoarthritis, the most common form of arthritis, occurs when the articular cartilage wears down. The articular cartilage lacks any type of blood supply and therefore cannot heal itself. Due to repetitive activity, the articular cartilage wears as we age and thins out much like treads on a tire. The process may also occur or be accelerated by previous injuries to the shoulder.
The symptoms of shoulder arthritis include pain throughout the shoulder that is generally poorly localized and “achy” in nature. Patients may report difficulty sleeping. The pain is usually worse with certain motions and there may be a grinding or catching sensation. As the arthritis progresses, there may be loss of range of motion of the shoulder.
The diagnosis of osteoarthritis of the shoulder is typically made based on a history of the patient’s symptoms, the findings on physical examination, and x-rays. Occasionally, an MRI scan may be ordered to exclude an associated rotator cuff tear.
Treatment of shoulder arthritis depends on the severity of the arthritis and the patient’s symptoms. Initially, non-surgical treatments are recommended and may include icing, rest and avoidance of aggravating activities, anti-inflammatory medicines, and possibly physical therapy exercises. A cortisone injection may be performed into the shoulder joint the help decrease inflammation and improve range of motion. If non-operative treatment fails to provide lasting pain relief, then shoulder replacement surgery may be recommended. In this procedure, the arthritic ends of the bone are removed and replaced by metal and plastic components to “re-surface” the diseased shoulder joint.
For more information, orthoinfo.aaos.org/topic.cfm?topic=A00222.