Bone spurs, or osteophytes, are bony growths that grow on bones that are trying to repair themselves. Because the shoulder is a complex joint with many moving parts and a wide range of motion, the bones, tendons, muscles and ligaments frequently rub against each other, and bone spurs can occur.
Bone spurs in the shoulder most frequently occur in the rotator cuff, the muscles that stretch from the shoulder blade to the upper arm. As the tendons move between this narrow space, they rub the bone and cause weak spots. Bone spurs can grow and pinch the rotator cuff tendon, resulting in weakness, pain and tension. Such injuries are frequent for athletes, especially baseball players and people who work with their arms above their heads, such as painters.