Friedrich's disease is a rare condition affecting the collarbone (clavicle) where it attaches to the breastbone (sternum). The patient reports pain or discomfort, swelling, and crackling or popping of the joint called crepitus. There may even be a loss of arm motion on that side.

The cause of this disease remains unknown. For some reason there is a loss of blood supply to the area. The bone starts to die and decay. This process is called osteonecrosis. The bone becomes fragmented with normal, healthy bone surrounding small islands of necrotic (dying) bone.

Most often the problem solves itself and treatment isn't needed. Sometimes the end of the bone must be removed surgically before healing can occur.