Acromioclavicular joint (ACJ) injuries

What is it?

The acromioclavicular joint (ACJ) is the area where your collarbone meets your shoulder blade. An ACJ injury,  therefore, is any break in a bone that makes up the shoulder joint, such as the proximal humerus (top of the arm), the clavicle (collarbone), or scapula (shoulder blade). The latter acts as a strut between the sternum (breastbone) and scapula, keeping the arm to the side of the body.

Why does it occur?

A direct blow sustained during a fall, during contact sports, or as a result of being in a road traffic accident, are sufficient to cause fracture in these bones. A less traumatic impact may cause injury in older patients who may have weaker and less robust bones.

Scapula fractures are much less common due, to the protection of the chest wall and surrounding muscles. As a result, this fracture will be as a result only of a high energy trauma.

What are the symptoms?

Severe pain, swelling and difficulty in moving the arm are the most common symptoms of such an injury. Depending on which bone is affected, a deformity may be evident, with surrounding bruising and a grinding sensation when attempts are made to move the arm.

How is it diagnosed?

In addition to taking a history and a physical examination, your surgeon will take radiographs of the shoulder to accurately determine the diagnosis. Occasionally a CT scan or MRI will be needed, in order to obtain a more detailed view of the fracture pattern, and to plan the best course of treatment. 

How is it treated?


The majority of such fractures can be managed without the need for surgery, but with the arm immobilised in a sling for a period of time. A plaster cast is not appropriate, due to the site and structure of the clavicle.

Surgery would be considered if the fracture is: shortened by 2 centimetres or more; displaced more than 100 per cent (the fractured ends aren’t touching at all); when there are specific fracture patterns (such as Z-type fractures); when the fractures are highly comminuted (splintered); or when there is overlying skin which is threatened by the pressure of bone pushing through. Surgery may also be necessary if a fracture has not healed after 3 to 6 months of if it is interfering with the function of other joints. 

Surgery in these cases would involve reducing the fracture and fixing the bone using either a rod or screws, and a plate.

Proximal humerus
The majority of fractures to this bone can be managed without surgery. An operation may be deemed necessary if the fractures involve the surface of the joint and are  particularly displaced. Any damage affecting the smooth articulate surface of the joint, which is not corrected, will cause uneven wear, and pain, over time.

Any decision to operate will  depend on the patient, including a consideration of their bone health, other health conditions and activity levels. Surgical options include fixing the fracture with a rod or plate and screws, and in some cases,  a complete joint replacement.

The majority of injuries to the should blade can be managed conservatively. However, a thorough assessment should be made to ensure there are no other associated injuries. Adequate analgesia, rest and ice are needed to ensure pain is controlled, and in the small number of injuries requiring surgery, plates and screws are used.

Treatment options

Shoulder replacement

Shoulder replacement

Shoulder replacement

The One Orthopaedics team specialists

Anthony Hearnden

Consultant Orthopaedic Specialist FRCS (Tr & Orth)