Metallosis occurs when the polyethylene lining that prevents the metal parts of artificial joints from creating friction and rubbing against each other wears out. The metal components come in direct contact and metallic fragments and ions become released into the surrounding tissue and blood stream. The metallic fragments and ions saturate the surrounding bone causing a painful soft tissue reaction and bone loss. Metal ions can also enter the blood and cause elevated levels of chromium and cobalt. Pain is caused by loosening of the prosthesis and the inflammatory reaction. When accompanied by elevated serum levels of chromium or cobalt, a metal hip joint likely has caused not only soft tissue reaction but a soft tissue mass or cyst as well. Artificial joints with have metal on metal components that cause pain or elevated levels of metal in the blood should be removed.