Acromioclavicular (AC) Joint injury is an injury occurring to the top (point) of the shoulder (where the front of the shoulder blade, called the acromion, meets the collarbone, or clavicle). It can be caused by repetitive overuse, especially with overhead motions, or by a traumatic event, such as a fall directly on the outside of the shoulder. AC Joint injuries most commonly occur in individuals younger than 35 years of age, with males 5 times more likely to sustain a more traumatic AC Joint injury than females. This age population is more prevalent due to the participation in high risk and collision activities, such as football, biking, snow sports, rugby, and ice hockey. The great news is that AC Joint injuries can be identified and effectively treated by a Physical Therapist, often avoiding the need for surgery.