Shoulder Specialist Logo

Where is the acromioclavicular joint ?

The acromioclavicular joint (also called the AC joint) is where the collarbone (clavicle) joins the shoulder blade (acromion). The joint is surrounded by a thin joint capsule and multiple ligaments providing joint stability. Vertical stability is provided by the coracoclavicular (CC) ligaments which consist of two parts, the conoid and the trapezoid and are found medial to the AC joint and pass from the coracoid process of the scapula to the clavicle.

How do acromioclavicular joint injuries normally occur?

The two most common mechanisms of injury are either a direct blow to the shoulder (often seen in football, rugby, or skating), or a fall on to an outstretched hand (often seen after falling off a bicycle or horse).

What are the clinical symptoms and signs of AC Joint disruption?

There will usually be a history of injury and sometimes severe pain over the front of the shoulder directly on top of the AC joint. A bony prominence is visible due to upwards displacement of the outer end of the clavicle which has become separated from the scapula.

Clinical appearance of disruption of the acromioclavicular joint
Clinical appearance of disruption of the acromioclavicular joint

How are acromioclavicular joint injuries treated?

This will depend on the severity of the injury and the activity level of the patient.

  • Mild injuries (Type I and II) are managed conservatively with ice, a sling for 1-3 weeks and anti-inflammatory drugs. Physiotherapy will start later to strengthen muscles around the shoulder.
  • With type III injuries, selected patients may benefit from surgical intervention. The management plan should be tailored to the individual patient.
  • Type IV-VI are nearly always treated with surgery which can be performed through key hole surgery or open reconstruction. Generally speaking, the results of surgery carried out for acute injuries are far better than chronic injuries.

Before surgery – note the upward displacement of the clavicle
Displaced clavicle

Same patient after surgery showing the clavicle has been reduced and is aligning normally with the acromion bone of the scapula.
Clavicle after surgery

Type V disruption before surgical repair
Type V disruption

Sometimes, 2 buttons are required for a more even distribution of stress across the repair
Showing 2 buttons

The information on this website does not replace medical advice. If you have a medical problem please see your doctor or consultant.