Q:  I am going to have surgery to stabilize my AC joint. It keeps dislocating and exercising it hasn't helped. What's the latest I should know about surgery for this problem?

A: The acromioclavicular or AC joint is the connection between the scapula (shoulder blade) and the clavicle (collarbone). Another term used to describe AC joint injuries is shoulder separation. A shoulder separation is a fairly common injury, especially in certain sports. Most shoulder separations are actually injuries to the acromioclavicular (AC) joint.

For more complete information on AC joint separation, see A Patient's Guide to Acromioclavicular Joint Separation.

AC joint separations are graded from mild to severe, depending on which ligaments are sprained or torn. The mildest type of injury is a simple sprain of the AC ligaments. Physicians call this a grade one injury. A grade two AC separation involves a tear of the AC ligaments and a sprain of the coracoclavicular ligaments. A complete tear of the AC ligaments and the coracoclavicular ligaments is a grade three AC separation. This injury results in the obvious bump on the shoulder.

The advancement of arthroscopic techniques has made it possible to repair or reconstruct grade three AC separations without making a large incision to expose the joint and its soft tissue attachments. And advancements have been made in surgical techniques and fixation devices (hardware used to hold the joint together until healing takes place).

For example, surgeons have found that the separated joint can be held together with a graft (ligamentous tissues taken from some other part of the body or from a donor bank). Efforts to develop a synthetic (manmade) graft substitute have failed so far. Surgeons have returned to natural graft sources taken from tendons in the patient's forearm.

They have also tried different suture techniques (e.g., suture sling fixation, cortical buttons, flip-button suture device) when putting the joint back together. Keeping the AC joint stable with load, movement, and activity is a challenge. For chronically dislocating AC joints, special "hook plates" have been devised to hold the widely separated joint together until soft tissue healing can take place.

The availability of these new graft and suturing techniques has made it possible for surgeons to refine their surgical technique. The treatment of chronic AC joint dislocation after failed conservative care is now possible with this new hardware technology.

Complications previously reported such as button suture migration (movement) and osteolysis (bone absorption) are greatly reduced now. These new fixation practices made possible by the use of arthroscopy has made the difference. In places where extreme trauma has resulted in an injured ligament that is not expected to heal, the combined use of new graft, suturing, and fixation techniques may make reconstruction successful now.

The open-incision surgical technique is still used by many surgeons. It makes the use of allograft tendon easier to reproduce anatomically correct ligaments for AC joint stability.

To summarize the answer to your question, the surgical management of acromioclavicular joint dislocations (shoulder separation) has been updated in the last few years. New techniques, improved fixation hardware, and the study of the biomechanics behind these injuries has led to better surgical treatment of these complex AC joint injuries.

More study is still needed to report on complications with various reconstruction strategies. Comparison of results between the open surgical treatment of AC joint injuries and partially open or closed (arthroscopic) procedures is also needed.

Reference: Cory Edgar, et al. An Update on the Surgical Management of Acromioclavicular Joint Injuries. In Current Orthopaedic Practice. November/December 2011. Vol. 22. No. 6. Pp. 488-493.