The same journal also reported that 170,000 people worldwide received artificial heart valves in 1994. As an alternative course of treatment, after unsuccessful attempts at physical therapy and non-surgical treatments, surgeons often turn to artificial devices to replace deteriorated joints. Bone plates, introduced in the early 1900's, were among the earliest successful biomedical implants. Artificial joints consists of a plastic cup made of ultrahigh molecular weight polyethylene and a metal or ceramic ball attached to a metal stem. The metals of choice are titanium or a cobalt-chromium alloy while ceramic materials are typically made up of aluminum or zirconium oxides.
Artificial joints can replace hips, knees, shoulders, wrists, fingers, or toe joints.
Replacement can help restore function to a joint that has been impaired by a degenerative disease or trauma from sports injuries or other accidents. In the U.S. alone, an estimated 300,000 patients receive joint implants every year. Material researchers are trying to find other materials to replace the ultrahigh molecular weight polyethylene in joint replacements. On average, the joint cups lasts about 10 years and researchers believe the joints can be made to last even longer. In fact, nearly everyone involved in orthopedic replacements agrees that the polymer cup is the final hurdle on the way to perfecting artificial joints.