MEDICAL DEVICE COMMUNITY TEAMS WITH NIST TO IDENTIFY BEST WEAR-RESISTANT MATERIALS FOR IMPLANTS

FOR IMMEDIATE RELEASE:                  NIST 96-34
Sept. 25, 1996

Contact: Roger Rensberger               MEDICAL DEVICE COMMUNITY
         (301) 975-2766                 TEAMS WITH NIST TO        
         roger.rensberger@nist.gov      IDENTIFY BEST WEAR-       
                                        RESISTANT MATERIALS FOR   
                                        IMPLANTS

     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: john.tesk@nist.gov.

     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. 
                                
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