Demographic changes in the industrialized countries, in particular the growing proportion of older people in the population, are increasing the number of patients being treated for degenerative bone and joint diseases. This trend has created an accelerating demand for replacement or repair of hip, knee and other joints with artificial materials, including polymers, metal alloys and ceramics. Ultrahigh molecular weight polyethylene is the most widely used polymer in joint replacement, although polyetherether ketone and several other engineering plastics have smaller roles.
Requirements for polymers and other materials used in artificial joints are stringent. They must have high strength and wear resistance to withstand repeated physical stresses over many years. They must also be biologically and chemically inert. Progress in polymeric materials for artificial joints tends to be evolutionary rather than revolutionary.
According to consultants Frost & Sullivan, the "rapid graying" of Europe's population will push the market for hip and knee replacement procedures in that region from an estimated USD 1.40 billion in 2004 to USD 1.83 in 2010.