This condition, also called AC joint arthrosis, is a degeneration of the joint at the top of the shoulder where the acromion meets the clavicle.

Osteoarthritis, also called degenerative arthritis, is a gradual breakdown of cartilage in the joints. Cartilage is a tough, flexible connective tissue that protects the ends of bones in the joints. Osteoarthritis of the shoulder can severely impact a person's lifestyle.