A new study, bringing together an interdisciplinary team ofphysicians and engineers from the United States and Germany, made asurprising finding Metal Spun Suppliers about implants used in hip replacement surgery:Graphite carbon is a key element in the lubricating layer thatforms on metal-on-metal hip implants. The lubricant has more incommon with the lubrication of a combustion engine than that of anatural joint. The study was funded by the National Institute ofArthritis and Musculoskeletal and Skin Diseases (NIAMS), part ofthe National Institutes of Health.

Made possible by an American Recovery and Reinvestment Act grantand to be reported online in the Dec. 23 issue of Science, "Thisfinding opens new avenues of investigation to help scientistsunderstand how joint implants function, and to develop strategiesto make them function better," said NIAMS Director Stephen I. Katz,M.D., Ph.D. "The results of such research could have importantimplications for several hundred thousand Americans who undergo hipreplacement each year - as well as those who could benefit from theprocedure, but have been advised by their doctors to delay surgeryuntil they are older." Touted as one of the greatest advances in arthritis treatment in history, hip replacement involves removing thedamaged hip and replacing it with a prosthesis to mimic the naturalball-in-socket joint.

"For most people, the procedure brings relief from pain and areturn to normal function for the life of the prosthesis, typicallymore than 10 years," said Joshua J. Jacobs, M.D., lead investigatorand chair of the Department of Orthopaedic Surgery at RushUniversity Medical Center in Chicago. But for younger, more activepeople, the prostheses' limited longevity often means postponingsurgery - often for a number of years, or having the surgery andfacing the prospect of a more difficult repeat surgery at somepoint when the prosthesis fails. For that reason, scientists havesought ways to improve the materials used.

One such way has been to design components with only metal-bearingsurfaces (so called metal-on-metal implants) rather than acombination of metal- and polyethylene-bearing surfaces that wereused almost exclusively prior to the 1990s, and tended to breakdown over time. But metal-on-metal implants, too, have issues. "We know there are metal-on-metal systems that have not performedwell," said Jacobs. "Problematic devices have tended to releasemore metal debris through wear and corrosion than devices that haveperformed well.