One of the joints about the shoulder is the acromioclavicular joint or “AC joint”. This is where the clavicle (collar bone) and acromion (part of the shoulder blade which makes up the top of shoulder) meet. This joint can be “separated” by a hard fall onto the shoulder which damage ligaments on the underside of the clavicle that hold the bones in alignment. The shoulder blade actually moves down in relation to the collar bone which creates a bump on the top of the shoulder.
Initial treatment is sling immobilization, ice, and pain control. Many of people with this injury can return to near full function, even in the setting of a persistent deformity/bump. If pain persists long term, a surgery might be recommended to trim down the end of the clavicle or reconstruct the ligaments. Surgery may be done arthroscopically and/or an open incision. With or without surgery, therapy is required to help restore function, mobility, and strength.