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What is the AC joint?

The acromoclavicular (AC) joint is where the collarbone (clavicle) connects to the bony tip of the shoulder (acromion). AC joint injury usually results from a fall directly onto the shoulder and is common in contact sports such as rugby. As the shoulder hits the ground the ligaments that surround and stabilise the AC joint are damaged. In less severe injuries there may only be a sprain (no tear) of the ligaments that does not lead to deformity. With increasing force, the ligaments attaching to the underside of the clavicle are torn leading to separation of the collarbone from the shoulder blade resulting in an obvious bump in the shoulder.


What are the symptoms?

At the time of the injury the area will be painful and shortly after bruising and swelling may develop. In the situation of a more severe injury where the ligaments have fully ruptured, there will be deformity with a “bump” on the top of the shoulder. After a few weeks the acute pain will settle and you will gradually regain motion in the shoulder. Unfortunately the ligaments do not heal and the deformity will persist. Not all patients get persisting symptoms, but those that do complain of pain and weakness that is particularly noticeable with overhead activities.

Acromoclavicular joint disruption
Acromoclavicular joint disruption

Will I need any further investigations?

Diagnosis is usually made on examination. X-rays are required to show the degree of AC joint disruption and to rule out associated injuries. More detailed scans are not required.

What are the non-surgical treatment options?

The initial treatment of most AC joint injuries consists of pain medication, application of ice to reduce swelling and a short period of rest using a shoulder sling. Shoulder motion can safely be started as pain allows, as there is little danger of causing any further harm. With the guidance of a physiotherapist, range of motion and subsequently strengthening exercises can commence. In most cases, the pain goes away within a matter of weeks and after a few months a full recovery is made. Of those patients that have sustained a complete disruption of the ligaments, there will be some that continue to get problems with pain, weakness and failure to return to their pre-injury level. Most surgeons take a “wait and see” approach although in some patients a decision is made to proceed with surgery at an early stage.

What does surgery involve?

Irrespective of whether surgery is performed within weeks, months or years after the injury, the principle is the same. The clavicle is realigned with the shoulder blade to restore the position of the AC joint. A variety of implants are available to maintain the connection while the ligaments heal. My preferred technique is to use a device called the Lockdown (Surgilig), which is a very strong braided polyester ligament designed to acts as a scaffold to encourage soft tissue in-growth. This is carried out through an incision over the top of the shoulder. The artificial ligament is passed around a portion of the shoulder blade (coracoid), over the top of the clavicle and secured in place with a single screw.

What is the success of surgery?

Generally, this is a safe and reliable operation to improve pain and allow the shoulder to return to normal strength and function.

What are the potential risks of surgery?

Any surgical procedure carries risks, however every effort is made to minimise these to ensure the best possible outcome from your surgery. The main risks of the operation include infection, bleeding, nerve damage and failure of the reconstruction. It is very difficult to achieve perfect symmetry of the joint to the other side and a mild residual deformity may be present.

What is the recovery after surgery?

The shoulder is rested in a sling for the initial 4 weeks after surgery to allow the tissues to settle. At this point you can begin safely moving the shoulder within your comfort zone. Physiotherapy is essential after the operation, to encourage good movement, rehabilitate the muscles back to normal function and ensure you are making good progress. You will see a therapist prior to discharge from the hospital. You will be given painkillers to take home after surgery. The use of an ice pack on the shoulder may also be helpful for the first few days after surgery. You will be seen in clinic two weeks after surgery to check the wound and assess your progress. There are no sutures to be removed. The pain will gradually settle and you will regain the movement in the shoulder over the next few weeks although it can take several months before you fully recover from the surgery.

When can I return to normal activities?

Return to work depends on the nature of the job and your speed of recovery. You can return to desk and computer work when you feel comfortable to do so but avoid any manual work, heavy lifting or sporting activities for around 3 months. You may return to driving when you feel safe to control the vehicle, which is usually about 2-4 weeks after surgery.

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