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The UHMWPE Lexicon is the online reference for ultra-high molecular weight polyethylene used in total joint replacements. The additional goals for this website are to provide an overview of state-of-the-art research in several key polyethylene related problems of clinical significance and to encourage hypothesis driven polyethylene research.
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2008 ORS Poster: Future Young Patient Demand for Primary and Revision Joint Replacement
Researchers from Exponent have developed updated nationwide projections for primary and revision TJR for the young patient population in the U.S. Using the most recent procedure data currently available for the U.S., previous projections were updated and the hypothesis was tested that patients younger than 65y will represent the majority (> 50%) of the anticipated demand for primary and revision TJR in the U.S. between 2010 and 2030. While researchers previously forecast a massive demand for primary hip and knee replacement, the current study underscores the major contribution that young patients are expected to play in the future utilization of primary TJR surgery.
2008 ORS Poster: In Vivo Oxidation, Oxidation Potential, and Clinical Performance of First and Second-Generation Highly Crosslinked Acetabular Bearings for THA
Highly crosslinked polyethylenes were developed to reduce wear in THA and are thermally processed by remelting or annealing. The main hypothesis was that highly crosslinked polyethylene formulations would have lower oxidation, oxidation potential, and lower head penetration than historical gamma-air and conventional gamma-inert sterilized liners. 109 highly crosslinked (90 - 105 kGy) retrieved components were compared with 48 gamma sterilized (25-40 kGy) controls. Penetration measurements were significantly lower in the highly crosslinked groups. Regional variations in oxidation were observed in all groups except for the remelted and sequentially annealed groups. The results of this retrieval study support the hypothesis that highly crosslinked polyethylene reduces in vivo wear, however the oxidation resistance was formulation-dependent.
2008 ORS Poster: Immunohistochemical Analysis of Periprosthetic Tissue from THR Revision Surgery
Researchers from Drexel University have developed a comprehensive approach to characterizing the specific and non-specific immune response of retrieved periprosthetic tissue from three cohorts of implant devices. Tissue samples were collected from THA revision surgeries of uncemented polyethylene (PE) hip components. The presence of macrophages, T cells, plasma cells and neutrophils was detected in tissue taken from historical, remelted and highly crosslinked polyethylene implants. These data provide the basis for a better evaluation of THR polyethylene-based inflammatory trends.
2008 ORS Poster: Polyethylene Particle Load Around Retreived Artificial Discs
The purpose of this study was to compare the polyethylene (PE) wear particle load of periprosthetic tissue from total disc replacement (TDR) with results from total hip replacement (THR) at the time of revision surgeries. PE particles were present in TDR and THR tissues, however the load for TDR implants was greater with pre-1998 TDR polyethylene components as compared the post-1998 polyethylene components. This is the first study to demonstrate a quantitative particle load comparison between TDR and THR periprosthetic tissue.
2008 AAOS Scientific Exhibit: Gamma Inert Sterilization: A Solution to Polyethylene Oxidation?
This study explores the hypothesis that implants sterilized in a low oxygen environment undergo similar in vivo oxidative mechanisms as implants sterilized in air. Over the past seven years, an multi-institutional retrieval program has traced and analyzed 264 conventional polyethylene hip and knee components. Measurable oxidation was observed in all cohorts. The oxidation was regional. Surfaces with access to bodily fluids were more heavily oxidized than protected, bearing surfaces. This variation appeared to be greater in gamma-air sterilized implants. The research therefore demonstrates that gamma inert sterilization may have improved, but not completely solved, the problem of polyethylene oxidation for hip and knee arthroplasty.
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Spine Technology Handbook
 A new frontier for surgical grade UHMWPE is in the field of spine implants. The Spine Technology Handbook, edited by Steven M. Kurtz, Ph.D., and Avram A. Edidin, Ph.D., is published by Elsevier Academic Press. The 16 chapters of the Spine Technology Handbook (560 pp.) describe the bioengineering principles, biomaterials, and designs of implants used in the treatment of spine disorders. Major technologies reviewed include devices used for fusion (screws, plates, rods, and cages), disc repair and augmentation, total disc replacement, and vertebral body repair and augmentation. An excerpt from Chapter 11, which discusses the use of UHMWPE in disc replacement, can be found here. Copies of the book can now be ordered through Amazon and Academic Press.
The UHMWPE Handbook: Principles and Clinical Applications in Total Joint Replacement
 The UHMWPE Handbook by Steven M. Kurtz, Ph.D., is published by Elsevier Academic Press. The 15 chapters of the UHMWPE Handbook (396 pp.) describe the history, properties, and clinical performance of biomaterials used for joint replacement. Copies of the book can now be ordered through Amazon, Barnes & Noble, Academic Press or your local medical or technical bookstore. Click here for the latest details about the UHMWPE Handbook.
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New Task Force Established to Develop a Standard Guide for UHMWPE Implant Components at ASTM
At the November 2007 ASTM meeting for F04, a new task force was created to develop an "umbrella" type document listing all of the recommended preclinical testing that should be performed for UHMWPE implants components by manufacturers. The scope will include conventional and highly crosslinked UHMWPE, with and without Vitamin E. This standard is expected to provide guidance for UHMWPE testing to manufacturers of hip, knee, upper extremity, and spinal implants. The intent of this proposed standard is to provide the basis for a future FDA guidance document for UHMWPE. Development of the standard will begin immediately via email, with the goal of providing a standard for ballot as soon as possible. Participation in this task force is open to all. To join the task force and participate in the early standard development process, please contact the Task Force Chair, Prof. Warren Haggard, U. of Memphis (whaggrd1@memphis.edu) or the Vice Chair, David Schroeder, from Biomet (Dave.Schroeder@biomet.com). The first face-to-face meeting of the task force, ideally to discuss the initial ballot results, is expected to take place at next ASTM meeting in May 2008.
Specification for Vitamin E-Blended UHMWPE To Be Published by ASTM; Task Force Disbanded
At the November 2007 ASTM meeting for F04, it was announced that the new draft standard, "Standard Specification for Ultra-High Molecular Weight Polyethylene Powder Blended With Alpha-Tocopherol (Vitamin E) and Fabricated Forms for Surgical Implant Applications," had successfully traversed sub-committee and main committee ballots and has been approved for publication. This specification covers Vitamin E-blended UHMWPE resin and fabricated forms of blended UHMWPE resin. The reference number (i.e., designation) for this standard is not yet available, but please check the ASTM site regularly for updates. Because no further revisions to this specification are planned in the near future, the task force voted unanimously to disband until further notice. No additional standards work on Vitamin E-blended UHMWPE is expected to take place at ASTM in 2008.
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