Six manufacturers of orthopedic medical devices are joining the National Institute of Standards and Technology in a cooperative effort to identify the best test methods for screening new, wear-resistant materials for use in orthopedic implants a move expected to significantly shorten the time for selecting such materials and getting them approved for use in medical devices.
Participants in the Orthopedic Accelerated Wear Resistance Consortium include Biomet Inc. (Warsaw, Ind.), Johnson & Johnson Professional Inc. (Raynham, Mass.), Osteonics Inc. (Allendale, N.J.), Smith & Nephew Richards Inc. (Memphis, Tenn.), Wright Medical Technology Inc. (Arlington, Tenn.) and Zimmer Inc. (Warsaw, Ind.). These companies manufacture 70 percent of the orthopedic implants fabricated in the United States. They also hold a commanding share of the global market by the manufacturers of orthopedic implants, which amount to approximately $3.5 billion annually.
John A. Tesk, the consortium's program manager in the NIST Polymers Division, notes that the effort will address a great concern of the medical device community: the degradation of implant materials through the wear process. Wear debris from artificial joint materials has been implicated in osteolysis (the dissolution of bony tissue) and may be a factor in the approximately 10 percent of artificial joints that fail. "Manufacturers of artificial joints consider the development of new, more wear-resistant materials a major priority," says Tesk.
Tesk explains that currently, prior to clinical applications, new materials for medical devices are evaluated through expensive and time-consuming in-vitro joint simulation studies in the laboratory. The number of new materials that may be evaluated at one time is limited, and this, therefore, reduces the likelihood of rapid improvement of joint implant prostheses.
Other material-screening test methods, such as pin-on-disk tests, are faster, but the results correlate poorly with those from simulators or clinical experience. Hence, these methods are not considered highly reliable and may even overlook promising new materials.
To help alleviate this problem, NIST will coordinate a research plan consisting of (1)a survey of technology, (2)round-robin testing of materials by consortium members using their wear-resistant test methods, (3)an analysis of the data, and (4)investigations into new test methods. Private-sector material manufacturers, Poly Hi Solidur (Fort Wayne, Ind.) and Teledyne Allvac/Vasco (Monroe, N.C.), have offered to assist the effort by supplying materials and sharing test information.
The development of an accelerated screening test for new materials will be an interlaboratory cooperative effort at NIST. Stephen M. Hsu, an expert on wear in the NIST Ceramics Division, will serve as the technical director for the consortium.
For information on the Orthopedic Accelerated Wear Resistance Consortium, contact John A. Tesk, A143 Polymer Building, NIST, Gaithersburg, Md. 20899-0001, (301) 975-6799, fax: (301) 963-9143, e-mail: firstname.lastname@example.org.
As a non-regulatory agency of the Commerce Department's Technology Administration, NIST promotes U.S. economic growth by working with industry to develop and apply technology, measurements and standards.