Dr Graeme MacDougal

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The Acromioclavicular Joint

The AC joint as it is commonly known, is a joint on the outer aspect of the shoulder between the clavicle (collarbone) and the acromion bone, which is an extension of the shoulder blade.

The clavicle acts as a strut to support and stabilise the scapula during activities which optimises the normal mechanics of the shoulder.

The main common conditions affecting the AC joint include those of arthritis and also shoulder trauma leading to various degrees of dislocation and occasionally fracture through this joint.


Arthroscopic Joint Surgery
It is common for acromioclavicular joint arthritic degeneration to be seen on plain x-rays and CT scans. It is also common that patient’s with these abnormal x-rays have little or no symptoms.

It is therefore essential that a thorough clinical examination and history be taken to assess whether a degenerate arthritic AC joint is responsible for the symptoms complained of.

Typically those symptoms may be related to tenderness over the AC joint, and occasionally referred pain into the trapezius and up the side of the neck. Acromioclavicular joint arthritis may respond to the use of oral anti-inflammatory medication, the application of ice or topical anti-inflammatories, corticosteroid injection or rest from activity.

Should these measures fail to reduce or eliminate the pain arising from the AC joint, consideration may be given to a surgical Arthroscopic Distal Clavicle Joint Resection, where approximately 1 cm of distal clavicle is excised via an arthroscopic technique.

Care is taken during this procedure not to damage the acromioclavicular joint capsular ligaments to avoid any postoperative increased motion or instability at the site of surgery.


Not dissimilar from the above problem, Acromioclavicular Joint Osteolysis is commonly seen in sports activities, in particular those who partake in gymnasium activity on a regular and high-intensity basis.

In this condition the acromioclavicular joint becomes inflamed and the synovitic process (inflammation) may lead to erosion at the end of the clavicle.

Swelling, pain and tenderness are common at the site of the joint affected, and non-operative treatments as suggested previously can be instituted.

Should these non-operative measures be unsuccessful in controlling symptoms, arthroscopic resection of the distal clavicle usually gives good symptomatic relief.

Some reduction in overhead strength may result from this intervention and should be taken into account when recommending this surgery.
AC Joint Dislocation

The acromioclavicular joint is commonly injured by traumatic conditions when people fall playing sport such as rugby, AFL, horse riding, skiing, mountain bike riding and surfing.

The common denominator here is a fall, usually leading to a direct blow to the side of the shoulder, or a fall onto the outstretched arm or hand.

The force is transmitted through the shoulder joint into the acromioclavicular joint, across the clavicle and distributed to the body.

Failure or dislocation of the acromioclavicular joint is not an uncommon scenario following these types of injuries, and there are a number of grades of injury between 1 and 6 which may result.

Low grade injuries I and II are usually managed non-operatively.

Injury grades IV to VI where dislocation is severe, are often candidates for surgical reconstruction.

Some controversy still exists over treatment of Grade III injuries (dislocations), and about the best way to manage these problems.

Non-operative treatments include anti-inflammatory medication, icing, physiotherapy and activity modification.

Grade III to VI injuries should be considered for surgical intervention and Arthroscopic Assisted Mini Open Techniques are available.

In these acute high grade injuries elevation of the clavicle occurs, sometimes penetrating the trapezius muscle.

Typically the ligaments between the coracoid and the clavicle (coracoclavicular ligaments) are torn, along with the coracoacromial ligaments.

The role of surgical intervention is advised early.

Surgery is aimed at relocating the clavicle and restoring alignment with the acromion and applying an “internal splint”. This re-approximates the coracoclavicular and acromioclavicular ligaments, to assist healing.

This internal splint (or scaffold) can be placed arthroscopically and a small mini open incision allows fine-tuning of the relocation, in addition to repair of the coracoacromial ligaments.

Should your shoulder have been recently injured, it is important to get an early assessment of that injury so as to allow early intervention where appropriate.

In the situation where a delayed referral is obtained and the injury is chronic, the healing potential of the coracoclavicular and acromioclavicular joint ligaments is reduced.

In this situation it is often necessary to excise the distal clavicle and perform a more extensive reconstruction of the coracoclavicular ligaments and the acromioclavicular joint capsule and ligaments.

Again this can be done through an Arthroscopic Assisted Technique, and the technique chosen will vary with the individual patient’s needs.


The acromioclavicular joint is a common site of pain, discomfort and reduced range of motion due to a combination of degenerate pathologies and also sports or traumatic related injuries.
  Any surgical or invasive procedure carries risks. Should you wish to discuss your acromioclavicular joint issue further with Dr MacDougal, please make an appointment to do so in order that your individual treatment needs can be prescribed for your particular situation.

Graeme MacDougal Shoulder and Elbow Surgeon