Pearls

1. Type 1: Sprain. Tender but no changes on X-ray.
2. Type 2: AC ligament tear, but CC ligaments intact. Slight displacement of the clavicle on the acromion on X-ray.
3. Type 3: AC and CC ligaments are torn. 25-100% displacement of the clavicle on the acromion on X-ray.
4. Type 4: AC and CC ligaments torn and the clavicle is posteriorly displaced. The clavicle can buttonhole through the trapezius.
5. Type 5: AC and CC ligaments are torn. >100% displacement of the clavicle from the acromion.
6. Type 6: Clavicle is inferiorly displaced to the acromion or the coracoid.

Type 1-3 are generally treated without surgery and PCP follow-up 2-weeks.

Bilateral AC joint x-ray can evaluate displacement compared to non-injured side.