The radiograph shows a grade 3 AC separation. Recommended treatment involves a sling for 10 days with early motion; in certain cases, surgery may be necessary.

Continue Reading

AC separations typically occur from an injury to the top or front area of the shoulder, often following a fall sustained during a high-velocity sport such as biking or skiing.  Similar to a patient with a shoulder dislocation, the patient with an AC separation will have a visible deformity and will be guarding the shoulder; however, upon closer examination range of motion will not be as limited and there will be focal tenderness to the AC joint.  The mechanism of injury is often different than with a shoulder dislocation as the mechanism of shoulder dislocation occurs when the arm is pulled backward.  

Testing for an AC separation involves radiography. If shoulder dislocation remains a concern after examination, a shoulder series can be ordered. If the provider is fairly confident about an AC separation, an AC view with or without a comparison view can then be ordered.  There are 6 types of AC separation, primarily differentiated by radiograph. Types 4, 5, and 6 are rare; type 3 demonstrates >1 cm separation, type 2 demonstrates 0 to1 cm separation, and type 1 presents with tenderness but normal imaging findings.

Related Articles

Treatment is conservative for most AC separations including types 1, 2, and 3. Surgery is recommended for some type 3 cases and most cases of types 4, 5, and 6.  There is no urgency for repair; patients seen in the emergency department can be referred to an orthopedist for follow-up care. 

The patient was discharged with orthopedic follow-up care for a type 3 AC separation. He did not require surgery.

Table. Types of AC Joint Separation

Brady Pregerson, MD, is an emergency physician at Cedars-Sinai Medical Center in Los Angeles and at Tri-City Medical Center in Oceanside, California.


Pregerson DB. Emergency Medicine 1-Minute Consult Pocketbook. EMresource.org. 2017;5.