Treated UHMWPE

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 9.2 Oxygen-functionalized surfaces improve the attachment and culture of osteoblast-like cells in vitro. Scanning electron microscopy showing human primary osteoblast-like cells (isolated from femoral heads) cultured on ultrahigh molecular weight polyethylene (UHMWP) surfaces with increasing surface oxygen concentration and tissue culture polystyrene (TCPS). UV/ozone-treated UHMWP samples showed elevated cell densities of osteoblast-Mke cells and cell morphologies which paralleled those observed in vivo. Individual scale bars are shown on the SEM images of 10 and 20 pm, and for the optical microscope images (TCPS) the scale bar indicates 100 pm.

Table 20.2 Surface Energy and its Components for XeCI Laser-Treated UHMWPE (Ultrahigh-Molecular-Weight-PE) Rbers Determined From Measured Contact Angles of Probe Liquids [129]...

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

Puukilainen E, Saarenpaa H, Pakkanen TA. Compression-molded, lubricant-treated UHMWPE composites. J Appl Polym Sci 2007 104 1762-8. 

Widmer and Spencer [9] treated UHMWPE with oxygen plasma. The treated surface was hydrophilic and had a faster and modified protein adsorption. A denser boundary layer of human serum albumin protein was found on the... 

Compression molding The HA-treated UHMWPE preform is molded to full density. 

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

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