The acromioclavicular joint (ac joint) is a joint that connects the clavicle and scapula. This joint is prone to developing degenerative changes. These degenerative changes include degeneration and tearing of the fibrocartilaginous disc that exists within the joint, in addition to the deterioration of the joint cartilage and 'bone spurring'.
This problem is more often seen in heavy laborers and weight lifters as a result of excessive repetitive physical stress on the joint from heavy lifting and carrying. The symptoms of this condition are shoulder pain and weakness.