Acromioclavicular (AC) joint injury

An AC joint injury is commonly referred to as shoulder separation, and is when the acromioclavicular joint is displaced.

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What is an AC joint injury?

The AC joint is the joint at the top of your shoulder between your collarbone (clavicle) and your shoulder blade (scapula). The AC joint is needed for the overhead and cross-body movement of your arm, as well as for giving you strength in physical activities such as pushing, pulling and lifting. A direct impact can injure your AC joint.

Need to know

Symptoms may include:

  • pain on the top of the shoulder which is exacerbated by heavy lifting, pushing, pulling and cross-body movements
  • swelling and/or bruising
  • restriction in your shoulder movements
  • if your collar bone (clavicle) is displaced a lump may be visible on top of your shoulder

AC joint injuries are graded by severity from Grade I (minimal joint disruption) to Grade VI (severe injury).

Your consultant will perform a physical examination of your shoulder and may conduct an X-ray or MRI to arrive at your diagnosis: These should be performed to assess the grade of injury which determines the best treatment options.

Treatment options correspond to the grades:

  • Grades I and II no displacement. These do not require surgery and most recover with a sling and mobilisation when comfortable. Very few may require a steroid injection if it remains painful.
  • Grade III some displacement/subluxation. This is mostly treated without surgery but surgery may be considered depending on your activity level.
  • Grades IV to VI complete displacement. These are usually treated with surgery. This involves the use of an artificial ligament. You may be in a sling after surgery, followed by physiotherapy.

Our Acromioclavicular (AC) joint injury locations

Institute of Sport Exercise and Health (ISEH)

Institute of Sport Exercise and Health (ISEH)

170 Tottenham Court Road W1T 7HA London
The Harley Street Clinic

The Harley Street Clinic

35 Weymouth Street W1G 8BJ London
The Portland Hospital

The Portland Hospital

205-209 Great Portland Street W1W 5AH London
The Princess Grace Hospital

The Princess Grace Hospital

42-52 Nottingham Place W1U 5NY London
The Lister Hospital

The Lister Hospital

Chelsea Bridge Road, SW1W 8RH London
The Shard Outpatients

The Shard Outpatients

The Shard, 32 St Thomas Street SE1 9BS London

Patient stories

This content is intended for general information only and does not replace the need for personal advice from a qualified health professional.