A 17 year old dirt bike riding Evel Knievel wannabe presents to the ED with right shoulder pain. He had crashed his bike earlier in the day. On exam he has normal strength and sensation in his hand and forearm, and is able to passively abduct his shoulder. There is no prior history of shoulder injuries. You do what you normally do and obtain XRays, which show the following.
This young man has a separation of the acromioclavicular joint – AKA the AC joint. The most common mechanisms of injury are falls onto the shoulder directly, then the good old FOOSH (fall on outstretched hand). AC injuries can be suspected on exam if there is asymmetry at the location of the joint. In addition, point tenderness at the joint and pain on cross-arm adduction (bring the arm across the body) are both suggestive but not diagnostic. For that you’re going to need X-Rays. vefore we talk about films I thought that it’d be helpful to review the joint itself. As you can see there are 4 ligaments that connect the clavicle to the scapula.