The acromioclavicular joint is the junction of the end of the collar bone (clavicle) with the roof of the shoulder (acromion). It frequently can be strained, inflamed, partially separated, or even dislocated. These conditions can be traumatic, related to overuse, degenerative, or even occur naturally with the aging process. Treatments might include medication, injection, and when treatment is refractory, consideration of surgical intervention.