Fluid-sorption phenomena in sterilized polyethylene acetabular prostheses

Clarke, Ian C.; Starkebaum, Warren; Hosseinian, Akram; McGuire, Paula; Okuda, Ryoji; Salovey, R.; Young, Robert W.

doi:10.1016/0142-9612(85)90007-9

Cited by 34 publications

(27 citation statements)

References 9 publications

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“…55 This was 50% higher than our nonirradiated soak cups (Table III) and clearly was a consequence of the 20 -30-kGy sterilization. Dynamic loading of the nonirradiated cups raised the absorption rates by 80%, and irradiating the cups to 500 -1500 kGy increased the absorption rates by a further 90%.…”

Section: Discussionmentioning

confidence: 87%

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Assessment of wear in extensively irradiated UHMWPE cups in simulator studies

Oonishi

Clarke

Yamamoto

et al. 2003

J Biomedical Materials Res

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Higher levels of UHMWPE crosslinking currently are being advocated for improved wear resistance of acetabular cups. Pioneering Japanese studies, begun in 1971, have achieved good clinical results with UHMWPE irradiated to 1000 kGy for use with a cemented-cup design. The objective of our study was to use contemporary simulator techniques to determine the in vitro wear performance of such high-dose irradiated cups. Extruded UHMWPE cups were processed with 500, 1000, and 1500 kGy of gamma-radiation doses under vacuum, annealed, and machined to shape. The cups were mated with 26-mm alumina heads and run in a multidirectional simulator with bovine serum. Over a 6-million cycle (Mc) study, the weight loss of the nonirradiated control cups averaged 52.8 mg/Mc + 1.4% (wear = 57.2 mm(3)/Mc). In contrast, the irradiated wear cups had a consistent weight gain. Thus cups with irradiation of 500-1500 kGy had no detectable wear in this study. The original machining marks still were partially evident in the wear zones, along with some macrofissures in the 1000- and 1500-kGy cups. Areas adjacent to the fissures showed delaminating plaques of 100-300 microm in size. It also was noted that the wear cups systematically gained more weight than their corresponding soak controls. Each 200-kGy radiation gain increased the fluid sorption ratio by 10%. The increased fluid sorption and evidence of some surface deterioration may indicate that such high-dose irradiated cups are more susceptible to mechanical damage. This indicates that we should take care to ensure that our desire to reduce the wear debris to a zero amount does not result in a modified UHMWPE that lacks the necessary mechanical properties for contemporary metal-backed cup designs.

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Section: Discussionmentioning

confidence: 87%

“…Figure 8. Increased UHMWPE fluid-absorption effects following 25-kGy radiation, as measured over 5 years of storage in various environments 55 .…”

Section: Discussionmentioning

confidence: 99%

Assessment of wear in extensively irradiated UHMWPE cups in simulator studies

Oonishi

Clarke

Yamamoto

et al. 2003

J Biomedical Materials Res

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“…The pre‐wear study of 42 days immersion was designed to stabilize the weight of polyethylene implants with regard to standard cleaning and weighing cycles used during the 180‐day wear study 35. This is the soak test before wear test.…”

Section: Discussionmentioning

confidence: 99%

“…The gravimetric method of wear assessment had the advantage that creep or cold flow in the UHMWPE inserts was not an issue. The disadvantage was that any weight changes due to fluid absorption into the UHMWPE should be compensated for 35. All tibial inserts were soaked in double‐distilled water 42 days prior to the wear study and cleaned periodically to assess weight trends (Sartorius Micro‐Balance: precision ±0.01 mg: ASTM F1714‐96).…”

Section: Methodsmentioning

confidence: 99%

Wear of sequentially enhanced 9‐Mrad polyethylene in 10 million cycle knee simulation study

et al. 2007

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Highly crosslinked polyethylene (HXPE) has been shown to be effective in reducing wear in total hip replacements. HXPE has not found widespread use in TKR, because the crosslinking inevitably leads to reductions in critical properties such as toughness and fatigue strength. Sequentially enhanced crosslinking (SXPE) have been suggested for improved wear resistance for tibial inserts with maintenance of mechanical properties and anticipated high oxidation resistance superior to conventional polyethylene (XLPE). We compared the wear of SXPE (9Mrad) to XLPE inserts (3Mrad) to 10 million cycles. Triathlon femoral condyles were identical in both. This is the first wear study of SXPE inserts. According to the power law relating irradiation dose to wear of XLPE inserts, wear of 9 Mrad inserts should be reduced by 70% compared to 3Mrad controls. The wear rates of the SXPE inserts were reduced by 86% at 10 million cycles duration, somewhat greater than predicted. The one prior investigation by the manufacturer reported a 79% wear reduction for SXPE compared to controls in a 5 million cycle simulator study in knee design and test parameters. There were important differences between the two studies. Nevertheless there clearly appeared to be a major benefit for sequentially enhanced polyethylene in tibial inserts. This combined wear reduction of 80-85% with improved oxidation resistance and retention of mechanical properties may prove beneficial for active patients who may otherwise risk high wear rates over many years of use.

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“…Wear assessment of total hip replacements (THR) is most commonly achieved by weight‐loss measurements. However, such gravimetric assessments have to account for various artifacts such as inadvertent flaking or chipping at interfaces, fluid absorption by polymer inserts, lubricant penetration into various crevices as well as proteinaceous and mineral coatings on the implant surfaces 1–5. For wear assessment of modular metal and ceramic balls there is a unique complication of metal transfer between the trunnion and the implant.…”

Section: Introductionmentioning

confidence: 99%

Discerning alumina ball wear from confounding metal transfer artifact

et al. 2005

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On dismounting a ceramic femoral ball from its metal trunnion, there is usually a range of gray metallic bands transferred to the trunnion bore inside the ball. This creates an artifact that may compromise detection by weight of the exceedingly low wear rates of ceramic balls. The objective of this study was to compare the weight trending of the metal trunnions and their ceramic balls during conditioning studies. Our hypothesis was that a pretest conditioning protocol would eliminate or greatly reduce the metal transfer artifact. The balls and tapers were placed on a hip simulator under 300-600 load cycles but with no articulation. The balls were then dismounted from the trunnions, and both were cleaned and weighed. This was repeated 6-23 times. We developed a novel hydraulic method for dismounting balls from trunnions that proved to be safe and efficient. There was significant weight loss in the trunnions after the ball removal, but there was no corresponding weight gain in the alumina balls. The weight effect of the metal transfer appeared to have been removed from the balls with our standard cleaning procedures. Therefore, wear rates for alumina balls may be gravimetrically determined without compensating for the metal transfer from trunnion to ball.

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Fluid-sorption phenomena in sterilized polyethylene acetabular prostheses

Cited by 34 publications

References 9 publications

Assessment of wear in extensively irradiated UHMWPE cups in simulator studies

Assessment of wear in extensively irradiated UHMWPE cups in simulator studies

Wear of sequentially enhanced 9‐Mrad polyethylene in 10 million cycle knee simulation study

Discerning alumina ball wear from confounding metal transfer artifact

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