Clinical and radiographic evaluation of the acromioclavicular joint

The acromioclavicular (AC) joint is a diarthrodial joint. It is only one of the five joints that make up the complexarrangement of the shoulder. Together with the sternoclavicular joint, the AC joint provides the upper extremity with a connection to the axial skeleton. Injuries to the acromioclavicular joint are very common in athletes and are a source of significant morbidity. AC pathology particularly affects athletes whose sport demands overhead upper limb activity. These problems are most frequently encountered in contact sports, are far more common in males, and may be responsible not only for aesthetically unpleasant deformities of the clavicle, but also for pain, fatigue, and muscular weakness. The treatment of injuries to the AC joint has been controversial since the time o£ Hippocrates¹ (460 to 377 B.C.). The classification by Rockwood has been accepted and there are six types.² Many treatment options have been proposed in the literature, targeted toward the different types of injuries, but it is difficult to compare the different series. The understanding of the anatomy, as well as accurate clinical diagnosis, is critical for the development of a successful treatment plan for both injuries and degenerative changes that may occur in the AC joint. AC joint pain may masquerade as other conditions in the shoulder, therefore, the pathology must be thoughtfully sought out. Careful clinical examination and basic radiographic imaging helps direct a clinically and cost effective approach to these problems.