Surface analysis of early retrieved acetabular polyethylene liners

Muratoglu, Orhun K.; Greenbaum, Evan S.; Bragdon, Charles R.; Jasty, Murali; Freiberg, Andrew A.; Harris, William H.

doi:10.1016/j.arth.2003.08.003

Cited by 83 publications

(22 citation statements)

References 9 publications

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“…The machine marks, which are 7 to 10 micra high, were still present. 25,26 A subsequently obtained electron-beamirradiated melted specimen retrieved after 3 years in vivo showed similar findings.…”

supporting

confidence: 82%

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Highly Cross-linked, Electron-Beam-Irradiated, Melted Polyethylene

Harris¹

2004

Clinical Orthopaedics and Related Research

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Extensive new evidence generated within the past the year provides strong support for the use of electron-beam highly cross-linked, subsequently melted ultra-high molecular weight polyethylene in total hip replacement arthroplasty. In terms of wear reduction, three studies involving three different demographic groups and two different measurement techniques have found that the femoral head penetration with this type of polyethylene after bedding in has finished taking place is less than 10 micra per year. This wear rate is similar to the wear rate of metal-on-metal and ceramic-onceramic articulations. Retrieval specimens up to 3 years after insertion confirmed the minimal wear by exhibiting persisting machine marks throughout the inside diameter of the liner. Extensive studies show no evidence of oxidation, confirming the absence of residual free radicals. No evidence of fatigue failure exists except three known cases out of 150,000, in which malposition of the acetabular component produced abnormally high contact stresses on unsupported polyethylene. The in vivo wear, oxidation resistance, and mechanical properties of this alternative bearing material are excellent, with in vivo durations now exceeding five years. The other major advantages over hard-on-hard bearings including familiarity, adaptability, forgiveness, and cost seem to be compelling.The list of advantages of electron-beam highly crosslinked, subsequently melted ultra-high molecular weight polyethylene (PE) as the preferred alternate bearing surface in total hip arthroplasty (THA) is extensive. It includes extremely low wear rate, absence of oxidation, the ability to use femoral large heads, familiarity, adaptability, forgiveness, the absence of the specific disadvantages of metal-on-metal couplings, the absence of the specific disadvantage of ceramic-on-ceramic couplings, and cost relative to hard-on-hard bearings.New in vivo data on wear reduction using this highly cross-linked PE in THA are strong. Two contemporary radiostereometric analysis (RSA) in vivo studies 12 of electron-beam-irradiated, subsequently melted, highly crosslinked ultra-high molecular weight PE attest to the high wear resistance that this cross-linking produces. In one of the two RSA studies, 12 54 patients were examined for a 2-year period with RSA, contrasting contemporary (gamma sterilization in nitrogen) versus electron-beam-irradiated, subsequently melted, highly cross-linked PE (10 Mrad e-beam irradiation) in patients having bilateral simultaneous THA using a modular, cementless socket. At 2 years, the highly cross-linked material showed a 90% reduction in proximal penetration of the femoral head compared with the control group (p ‫ס‬ 0.007). This is a considerable difference in penetration. After the first year, that is to say, after the bedding-in and creep had subsided, there was no detectable further penetration of the femoral head into the PE, which is noteworthy. The reduction in the 3-D penetration was also statistically significant (p ‫ס‬ 0.006).In the second RSA...

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supporting

confidence: 82%

“…The surface of retrieved specimens of highly cross-linked PE is heavily scuffed. 25,26 This probably is secondary to the third-body phenomenon. Two important observations have been made on this subject.…”

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confidence: 98%

Highly Cross-linked, Electron-Beam-Irradiated, Melted Polyethylene

Harris¹

2004

Clinical Orthopaedics and Related Research

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“…This ''shape memory'' is not entirely clear; another study performed in our laboratory did not observe the same return of machining marks [17]. We hypothesized that the difference in results could be the result of the relatively short implantation and simulation times in the studies by Muratoglu et al compared with the severe impingement simulation that we performed [17,[22][23][24]. The implantation times of the retrieved crosslinked liners in our current study were greater than those of Muratoglu et al, so determining the recoverability of the damage seen in this cohort is of interest.…”

Section: Discussionmentioning

confidence: 44%

“…However, at early followup, one would expect a smaller difference in wear quantitatively with early ''bedding in'' of the head into the crosslinked liner over the first year of implantation [3]. Previous studies have presented evidence of crosslinked liners having a ''shape memory'' such that machining marks can be recovered after remelting of the liners [22][23][24]. We did not perform remelting on the liners in this study but plan to perform this analysis in the future.…”

Section: Discussionmentioning

confidence: 98%

Retrieved Highly Crosslinked UHMWPE Acetabular Liners Have Similar Wear Damage as Conventional UHMWPE

Schroder

Kelly

Wright

et al. 2011

Clinical Orthopaedics &Amp; Related Research

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Background Highly crosslinked UHMWPE is associated with increased wear resistance in hip simulator and clinical studies. Laboratory and case studies, however, have described rim fracture in crosslinked acetabular liners. Controversy exists, therefore, on the relative merits of crosslinked liners over conventional liners in terms of wear performance versus resistance to fatigue cracking. Questions/purposes We asked whether crosslinked liners would show less surface damage than conventional liners but would be more susceptible to fatigue damage. Methods We examined 36 conventional UHMWPE and 39 crosslinked UHMWPE retrieved implants with similar patient demographics and identical design for evidence of wear damage, including articular surface damage, impingement, screw-hole creep, and rim cracks. Results We observed no difference in wear damage scores for the two liners. Conventional liners more frequently impinged but were more often elevated with smaller head sizes. We observed creep in approximately 70% of both types of liners. Incipient rim cracks were found in five crosslinked liners, and one liner had a rim fracture. Only one conventional liner had an incipient rim crack. Conclusions Contrary to our expectation, damage was similar between crosslinked and conventional UHMWPE liners. Moreover, the 15% occurrence (six of 39) of incipient or complete fractures in crosslinked liners as compared with a 3% occurrence (one of 36) in conventional liners may have implications for the long-term performance of crosslinked liners. Longer-term studies will be necessary to establish the fate of rim cracks and thus the overall clinical fatigue performance of crosslinked liners.

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“…■ Retrieval studies of implant components play a pivotal role in determining the efficacy of new designs that are introduced onto the market, and provide an invaluable resource for laboratory investigations that cannot be performed in vivo (Hailey et al 1994, Williams et al 1998. Analysis of retrieved devices that have been recently introduced onto the market can be useful in proving the worth of designs, materials and manufacturing methods, and can elucidate clinical factors that are important for successful implantation (Jones et al 2001, Morberg et al 2002, Muratoglu et al 2004). …”

mentioning

confidence: 98%