Evaluating the durability of UHMWPE biomaterials used for articulating surfaces of joint arthroplasty using delamination tests

Abstract

Ultra-high molecular weight polyethylene (UHMWPE) is the most popular material used for the articulating surface of joint replacements. Delamination is a common fatigue-related failure mode in UHMWPE components; however, the relationship between delamination resistance and fatigue crack growth has not been reported. Here, the delamination resistance of contemporary UHMWPE materials, including highly cross-linked UHMWPE (HXLPE), vitamin E blended UHMWPE (VEPE), and vitamin E blended HXLPE (VEXLPE), was measured to verify a previously proposed accelerated test method using a U-shaped sliding motion; the results were compared with those of fatigue crack growth tests. The oxidative stability of each material was estimated using Fourier transform infrared analysis. UHMWPE sterilized by gamma irradiation in an inert atmosphere and annealed HXLPE had lower delamination resistance than virgin UHMWPE after artificial aging. This was consistent with previous findings from retrieval studies, and in vitro knee simulator and ball-on-flat unidirectional reciprocation wear studies. In contrast, remelted HXLPE, VEPE, and VEXLPE showed excellent delamination resistance after artificial aging. The results of the delamination tests were not consistent with those of fatigue crack growth tests, indicating the complex delamination mechanism and importance of evaluating these factors separately. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2018.

In vitro estimation of reduction in strength and wear resistance of UHMWPE for joint prostheses due to lipid‐induced degradation

“…It has been reported that the fatigue properties obtained by fatigue crack growth testing do not necessarily coincide with delamination resistance (Sakoda et al, 2019). Therefore, in this study, delamination tests—which have been reported to be consistent with in vivo behavior—were also conducted (Sakoda et al, 2019).…”

“…It has been reported that the fatigue properties obtained by fatigue crack growth testing do not necessarily coincide with delamination resistance (Sakoda et al, 2019). Therefore, in this study, delamination tests—which have been reported to be consistent with in vivo behavior—were also conducted (Sakoda et al, 2019). Virgin used in this study was equivalent to ethylene gas‐sterilized UHMWPE, which has been reported to experience no delamination in vivo (Greulich, Roy, & Whiteside, 2012; MacDonald, Hanzlik, Sharkey, Parvizi, & Kurtz, 2012).…”

“…Virgin used in this study was equivalent to ethylene gas‐sterilized UHMWPE, which has been reported to experience no delamination in vivo (Greulich, Roy, & Whiteside, 2012; MacDonald, Hanzlik, Sharkey, Parvizi, & Kurtz, 2012). Therefore, a material having better delamination resistance than virgin is not at risk of clinical delamination (Sakoda et al, 2019). Since the delamination resistances of materials that simulated lipid‐induced degradation were higher than those of virgin, it is likely that lipid‐induced degradation does not create additional risk of delamination in vivo, regardless of crosslinking density.…”

“…Fatigue crack growth tests were conducted according to ASTM E647‐00 (2000) using compact tension specimens that were 36 mm long, 37.5 mm wide, and 10 mm thick (Sakoda, Osaka, Uetsuki, Okamoto, & Haishima, 2019). A pre‐crack was introduced with an unused knife, and a sinusoidal tensile load with a load ratio of 0.1 was applied at 1 Hz using a fatigue test machine (Servopulser EHFLV010K1‐A10, Shimadzu Corporation, Kyoto, Japan).…”

“…The same pin‐on‐plate wear test machine used for wear testing was used for the delamination tests with plate specimens with dimensions of 40 × 40 × 10 mm as previously described (Sakoda et al, 2019; Sakoda & Matsuoka, 2012). A load of 196 N was applied through a Co‐Cr alloy pin with a 3 mm‐radius hemispherical end.…”