Some joints in the body are more likely to develop problems due to normal wear and tear, or degeneration of the cartilage and joint lining. The type of arthritis that occurs due to degeneration over time is called osteoarthritis. The acromioclavicular (AC) joint, at the far end of the collarbone, is a common joint for developing osteoarthritis during middle age.
AC joint arthrosis, or osteoarthritis of the, acromioclavicular joint is most common in people who are middle aged. It develops when the cartilage in the AC joint begins to wear out. With this condition, there usually pain that limits the motion of the arm.