The collarbone forms the sternoclavicular joint with the sternum (breastbone) at one end and the acromioclavicular joint with the acromion (part of the shoulder blade) at the other end.

Acromioclavicular joint (Figure 5a) and GHJ pathology were the most common x-ray findings (both 17%) and calcification involving the rotator cuff was reported in 13% of subjects (Figure 5b).