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Tuesday, May 8, 2001
New highly crosslinked UHMWPE materials have been clinically introduced for the hip and are in the process of being clinically introduced in the knee. The materials have been developed based, in part, upon test methods and guides that were originally intended for unirradiated UHMWPE. In this workshop we reviewed standard test methods for conventional UHMWPE and explored how these methods may need to be updated or replaced for crosslinked UHMWPE. The goal of this workshop was to stimulate the development of test technologies for conventional and crosslinked UHMWPE.
Co-Chairs:
Steven M. Kurtz, Exponent, Inc., Philadelphia, PA
Ray Gsell, Zimmer, Inc., Warsaw, IN
Joshua J. Jacobs, Rush Presbyterian Hospital, Chicago, IL
Workshop Presentations
The power point presentations for selected speakers are now available for viewing in html format below. Click on a presenter's name to view the presentation in a separate window.
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Part A. Standard for Medical Grade Crosslinked UHMWPE? |
- Crosslink Density for Irradiated UHMWPE (S. Spiegelberg)
- Quantification of Radiation Dose for UHMWPE (O. Muratoglu)
- Standard methods for wear debris analysis for Crosslinked UHMWPE (H. McKellop)
- Oxidation Resistance and Shelf Life of Crosslinked UHMWPE (S. Kurtz)
- Mechanical Behavior of Crosslinked UHMWPE (A. Edidin)
- Wear Debris Isolation and Characterization (S. Jani)
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Part B. Validation Standard for Wear Testing of Crosslinked UHMWPE? |
- Introduction to Limitations of Wear Test Standards: The ISO Experience (L. Gilbertson)
- Critical Factors in Wear Testing of Virgin and Crosslinked UHMWPE: Temperature, Lubrication, Surface Roughness, and Fluid Sorption Effects (H. McKellop)
- Precision and Bias of RSA Techniques for Wear Estimation: Use of a calibration phantom (C. Bragdon)
- Standard Methods for Radiographic Wear Estimation: Use in validation of hip simulators (A. Edidin)
- What is the appropriate duty cycle for Total Knee Simulation (S. Banks)
- Load-Controlled vs. Displacement-Controlled Knee Simulator Testing of Crosslinked UHMWPE (A. Essner)
- Correlation between Mechanical Behavior and Clinical Performance (A. Edidin)
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Summary of Discussions at the Workshop
The workshop included two sessions intended to provoke discussion about crosslinked UHMWPE in total hip and knee replacements, as well as to identify fruitful areas for future standards development. During the first discussion section, concerns were raised that characterization of crosslink density and radiation dose may be redundant test methods. Many felt that current methods (e.g., dosimeters) provide sufficient means for characterizing the radiation dose for UHMWPE.
There was consensus that following topics could be considered for development as standards:
- Shelf Life
- Mechanical Behavior
- Wear Particle Size
During the second discussion section, concerns were raised about the state of knowledge with regard to use/performance of crosslinked UHMWPE in total knee replacements. There was interest in development of performance criteria for virgin and crosslinked UHMWPE in total knee replacements. There was consensus that round robin studies of radiological wear measurement would also prove useful.
Given the interest in new standard test methods and performance standards for crosslinked UHMWPE, a future ASTM Symposium on Crosslinked UHMWPE is recommended.
Task Force Meetings for UHMWPE at ASTM
Thursday, May 11, 2001
Discussion about new standards development for crosslinked UHMWPE continued during task force meetings devoted to UHMWPE Specification, Crosslinked Density of UHMWPE and UHMWPE Test Methods. Task force leaders were identified to work on new standards for shelf life of UHMWPE (R. Gsell), TVI analysis of radiation dose (S. Spiegelberg), and wear particle size characterization (S. Jani).
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