The acromioclavicular (AC) joint is the joint formed between your shoulder blade and the collarbone, on the top of your shoulder. The joint can be painful and patients often point, with one finger, directly to joint if is the source of the pain. The joint can also be unstable following injury to the ligaments, which connect the collarbone and shoulder blade.
Acromioclavicular joint pain
ACJ pain is common and associated with shoulder impingement syndrome. Wear and tear arthritis occurs and patients complain of pain over the joint, which is often increased when performing overhead activities.
Initial treatment includes activity avoidance, painkillers, physiotherapy and injections to the joint (often performed under ultrasound guidance).
Surgery for ACJ pain is performed by arthroscopic (keyhole) surgery as a day case. The joint is removed and the pain with it.
Acromioclavicular joint instability
Damage to some of the ligaments around the shoulder can lead to instability / displacement of the ACJ. This often follows an injury onto the point of the shoulder and is commonly seen in rugby players.
The majority of ACJ injuries are sprains of the ligaments and joint, and settle down with painkillers and physiotherapy. If the ligaments are completely torn and there is significant disruption of the joint (Fig 1) surgery may be required.
In acute (new) injuries surgery can be performed arthroscopically (by keyhole surgery), which reduces and holds the dislocation until the ligaments heal, as shown in (Fig 2).
In chronic (long standing) ACJ disruption where pain and poor shoulder function continues after an ACJ dislocation, surgery can be offered. The ligaments can no longer heal (due to the length of time that passes) and either an artificial ligament or a ligament graft is needed to reconstruct the joint. A LARS ligament reconstruction (Fig 3) is the graft of choice but using your own ligament grafts may be discussed.