What is it? The acromioclavicular (AC) joint is where the collarbone (clavicle) connects the highest point of the shoulder blade (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 (not 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.

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 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 a small 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.