The AC joint has several conditions that can cause pain, including:
Distal Clavicle OsteolysisDistal clavicle osteolysis is an unusual condition with no clear cause. Distal clavicle osteolysis is almost always seen in young men. In one study of 46 patients with distal clavicle osteolysis, 45 were young, male weightlifters. Exactly why weightlifters are prone to developing distal clavicle osteolysis is unclear, but there are tremendous forces exerted across the AC joint during many weightlifting activities, including overhead/military press and bench press.
The most common symptom of distal clavicle osteolysis is pain directly over the AC joint and the end of the clavicle. The pain is usually associated with activity, but there's also usually tenderness to pressure directly in this location. Swelling of the AC joint and surrounding soft-tissues may also be present. Pain when reaching across your chest is typical of AC joint problems; this is called a 'crossarm adduction test'.
The diagnosis of distal clavicle osteolysis can be made by obtaining an x-ray of the shoulder. Distal clavicle osteolysis initially shows up as an area of poor bone density or bone lacking appropriate mineralization, which can look like the bone loss of osteoporosis, a condition where more bone is absorbed by the body than created. An MRI is often obtained for two reasons: it can confirm the diagnosis of distal clavicle osteolysis, and it can also help to determine other possible causes of shoulder pain.
Treatment of Distal Clavicle OsteolysisThe treatment of distal clavicle osteolysis is usually successful with simple steps. The most important treatment is to avoid the activity that is causing the symptoms. As this condition is almost always seen in weightlifters, these activities must be avoided in order to allow the bone to heal. Other treatments can help to relieve pain, including ice application and anti-inflammatory medications.
Surgery can be performed for the treatment of distal clavicle osteolysis. In patients who fail to find relief with simple treatments, surgery may be an option to consider. The surgery for distal clavicle osteolysis removes the end of the clavicle—the area containing abnormal bone. This surgery is considered a distal clavicle excision, and is referred to by some doctors as a "Mumford procedure." This surgical procedure is the same procedure performed to surgically correct AC joint arthritis. About 1 cm of the end of the clavicle is removed. The surgery can be performed either through a small incision or arthroscopically.
After the end of the clavicle has been removed, the AC joint becomes wider, and the space fills in with scar tissue. Most people resume all normal activities with no loss of function after a distal clavicle excision. Total length of recovery after a distal clavicle excision is usually 3 months, but many patients resume routine daily activities in less time.
Beals RK and Sauser DD. "Nontraumatic Disorders of the Clavicle" J Am Acad Orthop Surg April 2006; 14:205-214.