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standards. (June 2010)| Replacement arthroplasty [from Greek
arthron, joint, limb, articulate, + -plassein, to form, mould,
forge, feign, make an image of], or joint replacement surgery,
is a procedure of orthopedic surgery in which the arthritic or
dysfunctional joint surface is replaced with an orthopedic
prosthesis. Joint replacement is considered as a treatment when
there is severe joint pain or dysfunction is not alleviated by
less-invasive therapies. Joint replacement surgery is becoming
more common with knees and hips replaced most often. As of 2009,
about 773,000 Americans have a hip or knee replaced each year".
Stephen S. Hudack, a surgeon based in New York City, began
animal testing with artificial joints in 1939. By 1948, he was
at the New York Orthopedic Hospital (part of the Columbia
Presbyterian Medical Center) and with funding from the Office of
Naval Research, was replacing hip joints in humans. Two
previously[when?] popular forms