Brief Outline of Acromioclavicular Separation

Acromioclavicular separation is a separation of the ligaments that connect the clavicle (collar bone) to the shoulder bones (known as the acromion process). Acromioclavicular (AC) joint injuries generally occur in the course of upper-extremity strength training, various throwing sports, and collision sports (particularly, football and hockey). The injury is common among athletes in their 30’s and 40’s.


AC Joint Dislocated

Anatomy and physiology

The arm is linked to the axial skeleton by means of the acromioclavicular joint, which connects the lateral end of the clavicle, and the medial border of the acromion of the scapula. A fibrocartilage articular disc partially divides the articular cavity, and absorbs forces and compression in the acromioclavicular joint is stabilised by anterior deltoid muscle, the trapezius muscle arising from the acromion, and additionally, by stabilising ligaments.

Cause of Acromioclavicular Separation

Fall onto the point of the shoulder. Fall onto an outstretched hand. Direct blow to the shoulder.

Signs and symptoms

Pain, tenderness, and swelling at the AC joint. Deformity of the injured joint. Pain or discomfort during cross-body adduction (turning the injured arm inward toward the opposite shoulder).

Complication if left unattended

Degenerative joint abnormalities, chronic pain and stiffness and limitations in mobility requiring surgery are possible, should the condition not be given prompt medical attention and allowed proper healing time.


Immobilisation of the injured arm with a sling.

Rehabilitation and prevention

AC separations of a less severe nature are successfully treated without surgery, though a thorough healing period of 6-8 weeks us generally required, following which, range-of-motion exercises should be used to avoid stiffness. Exercises directed at maintaining strength and stability of the shoulder and upper back muscles may help prevent the injury and use of padding around the AC joint, particularly during contact sports, may help avoid re-injury.

Long-term prognosis

Given adequate healing time and rehabilitation, most AC separations are resolved without surgery. Should surgery be required, risks of infection and continued pain exist, and recovery time for the athlete is lengthened.

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