Shoulder separation & AC joint injury

The AC joint sits at the top of the shoulder where the collarbone meets the acromion. A fall onto the point of the shoulder — from a bicycle, during football or hockey, or onto ice — drives the shoulder down and injures the ligaments that hold the collarbone in place. The result is pain and swelling over the top of the shoulder and, in higher grades, a visible step or bump.

Shoulder separation is graded I through VI according to which ligaments are injured and how far the collarbone has displaced. The grade matters because it guides treatment: low-grade injuries reliably heal non-operatively, while clearly displaced high-grade injuries are more often considered for surgery.

Symptoms appear immediately after the injury and localize to the top of the shoulder, which helps distinguish a separation from a rotator cuff problem or a true dislocation.

Any suspected separation with a visible deformity, severe pain, or an inability to use the arm should be evaluated promptly — imaging and grading early on shape the treatment decision. Lower-grade injuries that are still painful after several weeks, or that are keeping you from work or sport, also deserve a review rather than simply more rest.

Examination identifies tenderness at the AC joint and assesses stability, and rules out associated injuries to the rotator cuff, labrum and clavicle itself. X-rays confirm the separation and grade it; comparison or weighted views are occasionally used. An MRI is added when there is concern about other damage or when surgery is being planned.

Types I and II — and most type III injuries — are treated without surgery. A short period of sling support for comfort is followed by a progressive rehabilitation program restoring range of motion and then rotator cuff and scapular strength. Most athletes return to their sport within weeks for low-grade injuries.

When the joint remains sore after the acute phase, a cortisone injection can settle persistent AC joint inflammation, and platelet-rich plasma is an option some patients ask about for chronic joint or ligament pain — discussed on the PRP injections page. Structured recovery programs are outlined in the rehabilitation protocols.

Surgery is sometimes recommended for clearly displaced high-grade separations (types IV, V and VI), considered for some type III injuries in heavy laborers and overhead or throwing athletes, and offered for chronic separations that remain painful despite a full rehabilitation program.

Reconstruction restores stability between the collarbone and shoulder blade, using modern graft-based techniques rather than rigid hardware where possible. It is performed as an outpatient procedure, with return to full activity typically over four to six months depending on the demands of the sport or job.

Dr. Horner is a board-certified orthopedic surgeon fellowship-trained in shoulder surgery and sports medicine at Rush University Medical Center, with experience caring for professional and amateur athletes. The decision between rehabilitation and reconstruction is made on the grade of injury, the demands of your work and sport, and your goals — not on a default to operate.

Patients are seen at Oak Brook on Mondays, Little Village on Wednesdays and St. Charles on Thursdays.