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Acromioclavicular Joint (AC) Injury

What is it?

An acromioclavicular joint injury, otherwise known as a shoulder separation, is a traumatic injury to the acromioclavicular (AC) joint with disruption of the acromioclavicular ligaments and/or coracoclavicular (CC) ligaments. Those ligaments are part of the static stabilisers of the joint. In this injury the clavicle (collarbone) separates from the scapula (shoulder blade).

Different grades of AC injuries?


Grade I – A slight displacement of the joint. The acromioclavicular ligament may be stretched or partially torn.


Grade II – A partial dislocation of the joint. The acromioclavicular ligament is completely torn, while the coracoclavicular ligaments remain intact


Grade III – A complete separation of the joint. The acromioclavicular ligament, coracoclavicular ligaments and the capsule are torn.


Grades IV to VI – They are all treated surgically because of the severe disruption of all the ligamentous support for the arm and shoulder. They are very uncommon and are usually the result of a very high-energy injury such as that might occur in a motor vehicle accident.

Common Signs and Symptoms

May cause symptoms such as:

  • Pain

  • Limited range of motion in the shoulder

  • Swelling

  • Bruising

  • Tenderness at the top of the shoulder

  • You may be able to see that the collarbone is out of place or notice a bump on the shoulder

Common Causes

Acromioclavicular joint injuries account for 40-50% of athletic shoulder injuries. More commonly seen in males and athletes.

Injury happens when:

  • falling onto an outstretched hand or elbow

  • direct blows to the shoulder

  • falling onto the tip of the shoulder


Injury is frequently seen in hockey and rugby players, but is also seen in snowboarding, skiing, cycling and motor vehicle accidents.


  • Type I and II injuries usually have good to excellent results with return to full function in 1-3 weeks

  • Type III injuries usually return to full function in 6-12 weeks if non-operative

  • Type IV, V and VI generally require surgery and return to play depends on healing and restoration of near normal strength and range of motion.

Physiotherapy Treatment Options

The main goals of treatment for an AC joint injury are to manage pain and improve shoulder range of movement and strengthen muscles in and around your shoulders.

Grade I – III (Conservative management)


Phase I 

Goals: Pain management

  • Icing of the shoulder

  • Immobilisation of shoulder in a sling for 1-2 weeks

  • Consumption of pain medications as needed

  • Gentle passive range of movement

Phase 2

Goals: Increase range of movement and strengthening of the muscles around the shoulder and shoulder blades

  • Static shoulder strengthening exercises and progression to strengthening exercises with TheraBand

  • Shoulder mobilisation exercises

  • Strengthening of the muscles around shoulder blade


Phase 3

Goals: Progression towards functional and sporting activities and retraining of proprioception which is the body’s awareness of where a limb is in space. This is important to reduce the likelihood of re dislocation.

  • Progression of strengthening exercises through greater range

  • Progression of strengthening muscles around the shoulder blade in arms in over-head positions

  • Weight bearing exercises

  • Grade III may be managed conservatively, however surgery may also be indicated based on the severity of the symptoms. Overhead workers and athletes often require surgery.

Grade IV - VI (Conservative management)

  • Grade IV – VI injuries usually require surgical intervention to restore shoulder function.

Please note that you should always consult with your doctor or physiotherapist prior to attempting these exercises. Alternatively, feel free to call us on 1300 16 16 88 to speak to one of our physiotherapists to see whether these exercises are suitable for you.

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