Abnormal clavicle morphology Acromioclavicular joint separation 2025-10-05T16:01:13Z An acromioclavicular (AC) joint joint separation, often called a shoulder separation, is a dislocation of the clavicle from the acromion. This feature is ascertainable radiographically by AC joint x-ray views including bilateral anteroposterior (AP) view, axillary lateral view, and/or Zanca view showing either superior, posterior, or inferior displacement of the distal clavicle in relation to the acromion at the AC joint. The AC joint is a diarthrodial joint spanning from the medial articular facet of the acromion to the distal clavicle and links the shoulder girdle to the axial skeleton.