Acromioclavicular dislocation (displacement)
How does acromioclavicular dislocation occur?
Most of the lesions that affect AAC, causing disruption, occur in men and may result in dislocation of the distal clavicle in the event of ligament rupture. The most affected age group is in the third decade of life. It is difficult to say how common these lesions are, as population data are not available; however they appear to be highly prevalent among high-impact sports athletes.
It is often a fall on the shoulder with the arm in adduction (close to the body) or direct collision. It can also occur as a consequence of sports of repeated throwing or continued irritation by activities that require recurrent mobilization above the head, namely weight-lifting.
Acromioclavicular lesions may present with varying severity, ranging from simple ligament distension to dislocation and complete separation of joint surfaces.
What are the symptoms?
There is usually a history of major trauma and severe pain laterally in the shoulder. Marked swelling of the AAC or a visible or palpable bump may occur if there is clavicular separation, more evident with the limb along the body.
The position of the clavicle should be determined throughout its length. The radial and brachial pulses, as well as the sensory and motor functions of the affected limb, should be evaluated for the possibility of injury to the brachial plexus and axillary and subclavian vessels.
How is the diagnosis made?
The diagnosis is made by radiographs. These x-rays can be performed under stress. In rare cases, CT scan may be indicated.
Which therapeutic options are available?
There is controversy over surgical versus conservative treatment, particularly in lesions with little deviation.
Conservative treatment is indicated in lesions with little deviation, and consists of the application of ice, antebrachial suspension for one to three weeks and anti-inflammatory drugs, followed by physical therapy to strengthen muscles and ligaments after acute phase. Type III lesions (with greater deviation) should be treated conservatively but in some selected cases may benefit from surgical treatment.
Surgery is indicated in very deviated lesions. Complications may include development of subacromial impigment syndrome, CAA arthrosis or frozen shoulder.