HIP Action

The success of hip implants with elderly recipients has encouraged surgeons to increasingly perform hip replacement surgery on younger, more active patients as well. The condition that causes hip prostheses to loosen is known as osteolysis. While the problem affects only a relatively small set of recipients now, it may well grow as hip replacement surgery encompasses a wider range of eligible patients. A research group at the University of Leeds in the United Kingdom says it has patented a ceramic-on-metal hip prosthesis that produces one-tenth the wear particles of currently available hip replacement joints. The prosthesis has been licensed to a prosthetic manufacturer and is about to enter clinical trials in Europe. Some companies produce highly cross-linked polyethylene, either by thermal treatment or by radiation. Stryker Orthopaedics has Crossfire hip implants using highly cross-linked polyethylene cups against a metal ball. The company developed a ceramic-on-ceramic joint replacement, which it commercialized in 2003. The new Trident joint uses bearing surfaces of alumina ceramic. The company claims it has scratch resistance, low wear rates, good wettability for lubrication, and no ion release.