Knee replacements double as aging patients stay active

Total knee replacement procedures rose 162 percent from 1991 to 2010 while the number of procedures to repair a previously implanted artificial knee joint, called revision, jumped 106 percent, according to research released in the Journal of the American Medical Association. About 600,000 total knee replacement procedures, done to relieve symptoms of severe knee arthritis, are performed each year in the U.S. costing about $9 billion annually, according to the research. About 60 percent of those procedures are paid for by Medicare, the federal government health program for the elderly and disabled, said Peter Cram, the lead study author.