TOTAL SHOULDER REPLACEMENT What is shoulder arthritis? The shoulder joint is a ball and socket joint. The joint surfaces are normally covered by a smooth cartilage layer. Arthritis is a degeneration of the joint cartilage. Over time, the cartilage becomes thin, sometimes to the point that bone rubs on bone inside the joint. This process eventually leads to bone spurs and painful scar tissue in and around the shoulder joint. What are the symptoms and treatments of shoulder ...