The ball and socket joint (glenohumeral joint) can develop arthritis. There are many different causes of arthritis the most common is wear and tear (osteoarthritis), other types include inflammatory (eg rheumatoid) or it can occur secondary to trauma. Arthrits can also follow after massive rotator cuff tear this called rotator cuff tear arthropathy, to read more about this condition click here.
In an arthritic joint, the cartilage covering is worn away, this causes a loss of the shock absorbing features of the joint resulting in bone rubbing on bone. This causes pain which occurs on movement and in more severe cases at rest also. The overall movement of the joint is restricted and as a result function of the arm is reduced.
An X-ray will usually confirm the diagnosis. If surgery is planned a CT scan will be needed to check the orientation of the bone in the socket and how much bone is present to safely perform the surgery.
This X-ray shows osteoarthritis with loss of joint space and extra bone formation (osteophytes).
Initial treatment includes anti-inflammatory medication and physiotherapy. A steroid injection can be considerered in mild cases.
If symptoms are severe and the joint is destroyed then surgery maybe required. This is usually a shoulder replacement. It is generally accepted that shoulder replacement is a good operation for pain relief. The amount of movement above shoulder height will be determined by function of the rotator cuff.
In wear and tear arthritis (ostearthritis) the rotator cuff is usually intact, in this situation shoulder replacement can expect to give good movement as well as pain relief. In inflammatory arthritis often the tendons are also affected by the disease. This means that the tendons may be torn or diseased, this can result in poor movement above shoulder height even after successful joint replacement.
The diagram below shows a total shoulder replacement with stemmed humeral head replacement and polyethylene socket replacement.