Clinical wear

McKinney, Antonucci Rupp (1987) found that the clinical wear of the glass polyalkenoate cement compared favourably with that of the composite resin, but they noted that it was prone to brittle fracture and chemical erosion. 

Dr. Wroblewski starting in 1986 (1996). After an initial bedding-in period, these crosslinked HDPE components have been found to exhibit very low clinical wear rates. 

Range of Clinical Wear Performance in Cemented Acetabular Components... 

Current Methods for Measuring Clinical Wear in Total Hip Arthroplasty... 

Sauer W.L., and M.E. Anthony. 1998. Predicting the clinical wear performance of orthopaedic bearing surfaces. In Alternative bearing surfaces in total joint replacement. J.J. Jacobs and T.L. Craig, Eds. West Conshohoken American Society for Testing and Materials. 

The potential for extremely low clinical wear rates, necessary to reduce the risk of osteolysis, has led to renewed interest in developing new COC designs for hip arthroplasty during the 1990s (Boehler, Plenk, and Salzer 2000). In addition, the desire to reduce the fracture risk has led to continuous improvement of ceramic maferials for orthopedic load bearing applications over the past since the early 1980s (Table 6.2). 

MOM, COC, and highly crosslinked acetabular liners— used in conjunction with either a CoCr or ceramic femoral head—have the potential to significantly reduce the clinical wear rates of THRs relative to the existing gold standard of conventional UHMWPE. All three of these alternative bearings incorporate the... 

Wear testing by Essner and colleagues in a multidirectional hip simulator for up to 10 million cycles demonstrated that Duration exhibited 32% less volumetric wear than air-irradiated control UHMWPE (1997). However, in a recent radiostereometric study by Nivbrant and colleagues, the clinical wear rate of Duration was not significantly different than an air-irradiated control UHMWPE after 2 years of follow-up (2003). 

Atwood SA, Currier JH, Mayor MB, Collier JP, Van Citters DW, Kennedy FE (2008), Clinical wear measurement on low contact stress rotating platform knee bearings , J Arthroplasty, 23, 431 0, DOI 10.1016/j.arth.2007.06.005. 

Table 2. Combined clinical wear data of the work of Oonishi et al. [89,93] on y-irradlated UHMWPE...

Ohashi T., Inoue S., Kajikawa K., Ibaragi K., Tada T., Oguchi M., Aral T., and Kondo K. 1988. The clinical wear rate of acetabular component accompanied with alumina ceramic head In Bioceramics. Proceedings of 1st International Symposium on Ceramics in Medicine. H. Oonishi, H. Aoki, and K. Sawai (Eds.), pp. 278-283. Ishiyaku EuroAmerica, Inc. Tokyo. 

During the 1980s, two other noteworthy developments occurred relative to polyethylene in joint replacements. In the early 1980s, Char F. Thackray, Ltd. of Leeds began development on an injection molded HOPE that could be crosslinked by silane chemistry (the same type of crosslink-ing used in silicone polymers) [5, 6]. Only 22 of these implants were produced and implanted by Dr. Wroblewski starting in 1986 [7]. After an initial bedding in period, these crosslinked HOPE components have been found to exhibit very low clinical wear rates. 

Introduction 5.5 Comparing Wear Rates Between 5.8 Range of Clinical Wear... 

Range of Clinical Wear Clinical and Retrieval Studies 5.9 Conclusion... 

RANGE OF CLINICAL WEAR PERFORMANCE IN CEMENTED ACETABULAR COMPONENTS... 

Chamley [26, 28] and has been observed in subsequent studies using contemporary modular hip designs [7]. For this reason, it is sometimes more useful to characterize clinical wear performance using nonparametric statistical methods, which make no assumptions about the underlying distribution of the data. A box and whiskers plot (or more simply, a box plot), shown in Figure 5.6 for the same wear data as in the histogram derived from Chamley and Cupic s study [26], is helpful to summarize the distribution of the wear data. 

CURRENT METHODS FOR MEASURING CLINICAL WEAR INTHA... 

As summarized in the previous section, laboratory tests of ceramic biomaterials have demonstrated substantial advantages over CoCr for articulation against UHMWPE. The harder ceramic surfaces should theoretically be more scratch resistant than CoCr femoral heads [125, 126]. Unfortunately, it has thus far proven difficult to conclusively establish, as a general premise, the clinical benefit of ceramic femoral heads in patients. For reasons noted previously associated with in vivo phase transformation and surface roughening of zirconia, clinical wear studies pubUshed in the past 5 years with zirconia heads have reported nuxed results in the literature, ranging from no significant difference to inferior performance relative to CoCr heads. 

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