AC Joint / Shoulder Separation

The AC joint connects the collar bone (clavicle) to the shoulder blade (scapula). This joint can get injured in fall or forceful motion to the shoulder. Patients typically complain of pain on top of the shoulder and may notice a step-off where the injury occurred. The pain usually subsides in a few days but the deformity never goes away.

There are two ligaments which hold the collar bone to the shoulder blade. The acromioclavicular (AC) ligament envelops the joint and prevents motion in the horizontal plane. The coracoclavicular (CC) ligaments are oriented vertically to prevent vertical translation of the AC joint. In a shoulder separation, one or both of the above ligaments may be injured. Treatment of a shoulder separation is based on the severity of injury.

Options for treatment include placing the patient in a sling. This is usually utilized for mild cases in which the step-off in the joint is not so severe, and the CC ligaments are intact. The sling is usually used for a few weeks, which is followed by a course of physical therapy.

Surgery is reserved for the more severe shoulder separations. The surgery is an outpatient procedure which consists of a distal clavicle resection and a ligament repair or reconstruction. During the distal clavicle resection, the clavicular end of the AC joint is excised to allow the joint to move freely without friction. Depending on the timing and severity of the injury, the CC ligaments will either be repaired or reconstructed. If reconstruction is needed, a cadaveric tendon is used to reconstruct the torn ligaments to align the AC joint to its normal position. This involves making a small incision over the joint itself to allow the passage and reconstruction of the ligaments. After surgery, a sling or brace is worn for about 4-6 weeks. Sutures are taken out two weeks after surgery. Physical therapy is carried out after to restore the shoulder motion and strength. Although the surgery will eliminate most of the visible bump seen on top of the shoulder, you may continue to see a small step-off between the collar bone and the shoulder blade.

Further information about shoulder separations can be found in this handout, or on the AAOS OrthoInfo website.