Page 86 - Demo

Chapter 384α-tocopherol. This is of course of great importance, as a lower degree of crosslink density results in lower wear resistance. When diffusing vitamin E into the crosslinked UHMWPE has no effect on the crosslinking density and thus higher concentrations can be achieved. Of course, as long as α-tocopherol has not been applied to the UHMWPE, oxidation degradation can occur.(63) Also Bracco et al.(63) found that vitamin E-stabilized UHMWPE had better mechanical strength and showed less deterioration compared to non-treated UHMWPE, as long as a correct dosage of both vitamin E and radiation was applied. Furthermore, Wolf et al.(65) have come to prove through animal studies that the addition of vitamin to UHMWPE has no cytotoxic or genotoxic effect. It should be noted that, although UHMWPE is very suitable as an interpositioning material between load-bearing surfaces, care should be taken when using UHMWPE as the sole component of the fossa because of the increased risk of creep, fracture and back-side wear, and poor surface fixation with bone and bone cement originating from the hydrophobic nature of UHMWPE, which can result in micromotion.(13,38) Despite these potential drawbacks, the fossa of the Biomet system is made solely of UHMWPE, which is fixated with Ti6Al4Vscrews. To our knowledge, there have been no systematic findings of failure of the Biomet system’s fossa. A 3-year follow-up study after placement of a Biomet prosthesis conducted by Sanovich et al.(39) reported four implant failures, only one of which was due to loosening of fossa screws. Giannakopoulos et al.(7) and Leandro et al.(8) performed follow-up studies of 288 and 300 patients, respectively. The authors of both studies concluded that the system produced satisfactory results, with a 3.2% failure rate in the study by Giannakopoulos et al.(7) and an absence of device-related failure in the other study. Despite high success rates, varying between 84% and 91%, it should be noted that only a limited number of studies are available in literature and most of these involved small numbers of patients and relatively short follow-up periods (3 to 10 years).(7,8) Nikolas de Meurechy NW.indd 84 05-06-2024 10:14