Injuries and conditions

Acromioclavicular Joint Dislocations (Shoulder separation)

Acromioclavicular Joint Dislocations (Shoulder separation)

Acromioclavicular Joint (ACJ) dislocations are very common and may occur due to a simple fall, playing sport, fall of a bicycle, or in a motor vehicle accident. It is important to understand the exact pattern of the dislocation (using 3D CT scans and/or MRI) and the patients expectations around healing and recovery. Any other associated injuries, such as a SLAP tear, should be identified. Most patients can be managed without surgery; if surgery is required it is best to undertake that sooner rather than later.

The roof of the shoulder (Acromion) and the end of the collarbone (Clavicle) form a joint – this is referred to as the Acromio-Clavicular Joint (ACJ). When an injury occurs, such as by a direct fall onto your shoulder, this joint can dislocate. As the Collarbone and Acromion separate they will tear other ligaments that hold down the collar bone. The severity with which this happens allows us to grade the AC Joint separation into six grades; the higher the grade/number, the worse the dislocation and the more likely you will need surgery.

2 shoulder scans showing AC Joint Dislocation

This injury is more common in younger patients and those that take part in collision type sports (such as rugby and soccer) and cycling. The most common mechanism of injury is a direct blow to the shoulder, often sustained after falling onto the shoulder. This injury may also occur in higher energy situations such as a motor vehicle accident.

In most cases, the diagnosis is obvious and directly after trauma with an immediate presentation to the emergency department. Signs and symptoms of a clavicle fracture include:

  • Visible deformity (or a bump) about the end of the clavicle and shoulder girdle; in some cases, there is skin “tenting” due to the end of the collarbone raising the skin
  • Bruising, swelling, and/or tenderness over the AC Joint.
  • A clicking or grinding sensation with arm movement, particularly overhead
  • Inability to raise arm due to pain
  • Change in shoulder contour

In lower grade injuries (grade 1 or 2), the injury may initially be missed and treated as a shoulder sprain. In higher-grade injuries (grade 3 and beyond), patients often present to the hospital after injury. Usually, a bump is present over the end of the collar bone and the diagnosis is confirmed on X-ray. Sometimes a comparison X-ray of the unaffected shoulder is required to confirm the grade of injury.

In a small number of cases, a CT scan or MRI is required to confirm the grade of dislocation and exclude other associated conditions (such as a rotator cuff tear or SLAP tear).


Most cases are grades 1-2 and  can be managed without surgery with a sling, period or rest, analgesia, and a graduated rehabilitation program allowing the ligaments to heal over time (3 months).

A self-directed rehabilitation program using the JPL program is commenced between 4-6 weeks after the pain and soft tissue swelling have settled. Usually, patients are followed up at 1-2 weeks with a repeat X-ray to confirm the ACJ dislocation remains in a good position.

By 4-6 weeks patients can come out of a sling and commence active range of motion. The ligaments should heal by 3 months and at which point a strengthening program may be commenced.


This is reserved for ACJ dislocation grades 3 and above. See below for more information.

Table of information describing the classification of AC joint dislocations using the Rockwood Classification method

Generally speaking, Grade I and II injuries do NOT need surgery and will do fine with a sling, analgesia and physiotherapy.

Grade III injuries are often managed without surgery; however, in select cases, they may do better with surgery – this is a case by case decision.

Grade IV, V and VI injuries should be stabilised. This is because they are inherently unstable and if left untreated will reliably result in loss of shoulder function, particularly with overhead activity.

Sportspersons and those with occupations that require their arm to be at chest height or higher should be treated with more consideration and offered earlier surgery when appropriate.

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