Highly Crosslinked and Thermally Treated UHMWPEs

Scientific and commercial developments related to radiation crosslinking and thermal treatment of UHMWPE are evolving at a rapid pace. At the time of my first review on this topic, written between 1997 and early 1998, highly 

Comparison of starting stock materials and processing conditions used to produce contemporary thermally 

Because this chapter deals primarily with proprietary materials, the contents of this chapter were verified for accuracy with the individual manufacturers by the author. Some process details were not, however, provided or confirmed by the manufacturers. When manufacturers were reluctant to provide certain detailed information about their processes, we relied on previous published sources as the basis for tire reported process conditions. A recent symposium on this topic, convened by tire American Society and Testing Materials (ASTM) in November 2002, also provided a wealth of information about today s highly crosslinked UHMWPEs. The peer-reviewed proceedings of that symposium (Kurtz, Gsell, and Martell 2003), printed by ASTM as a special technical publication, were key references when compiling this chapter. 

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In the next section, we first briefly review the historical experience of highly crosslinked UHMWPE for hip replacement and summarize the general characteristics of contemporary materials in current clinical use. The next section also describes the effect of thermal treatment on the properties of fhis family of materials. In the final part of this section, we summarize the latest short-term clinical results using highly crosslinked and thermally treated UHMWPE. For more detailed information about specific highly crosslinked formulafions, see Chapter 15. 

Contemporary Highly Crosslinked and Thermally Treated UHMWPEs... 

The six highly crosslinked and thermally treated UHMWPE materials described in this chapter are gaining increased prevalence in THA, but they have thus far accomplished only limited penetration into TKA. The prevalence of these new materials is governed not only by physician acceptance, but also by the availability of patents and/or licenses to the technology, which are controlled by a handful of manufacturers. 

First, despite their recent clinical introduction, highly crosslinked and thermally treated UHMWPE materials are now used in the majority of hip replacements in the United States. During 2003, highly crosslinked UHMWPE materials are projected to be used in an estimated 65% of U.S. hip arthroplasties (Table 15.7). Crossfire, Marathon, and Longevity have the greatest market share in the United States, and these three materials alone are estimated to accoimt for 55% of hip replacements performed in 2003. 

FIGURE 6.20 Route for production of first generation highly crosslinked and thermally treated UHMWPE that includes a proprietary combination of three important factors. 

Abt N.A., and W. Schneider. 2003. Influence of irradiation on the properties of UHMWPE. In Highly crosslinked and thermally treated ultra-high molecular weight polyethylene for joint replacements. S.M. Kurtz, R. Gsell, and J. Martell, Eds. West Conshohoken, PA American Society for Testing and Materials. 

McKnulty D, and S. Swope. 2003. The effect of crossUnking UHMWPE on in-vitro wear rates of fixed and mobile bearing knees. In Highly crosslinked and thermally treated... 

Abt NA, Schneider W, Schon R, Rieker CB. Influence of electron beam irradiation dose on the properties of crosslinked UHMWPE. In Kurtz SM, GseH RA, Martell J, editors. Crosslinked and thermally treated ultra-high molecular weight polyethylene for joint replacements. West Conshohocken, Pa. ASTM International 2004. 

The clinical introduction of a highly crosslinked, irradiated and thermal treated UHMWPE (HXLPE) in the late 1990s provided a significant... 

FIGURE 20.1 Comparison of starting stock materials and processing conditions used to produce first-generation thermally treated and highly crosslinked UHMWPE materials for TKA and THA. 

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