Cracking and Impingement in Ultra–High-Molecular-Weight Polyethylene Acetabular Liners

Birman, Michael V.; Noble, Philip C.; Conditt, Michael A.; Li, Steve; Mathis, Kenneth B.

doi:10.1016/j.arth.2005.05.001

Cited by 56 publications

(34 citation statements)

References 15 publications

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“…The average wear rate of our retrieved specimens was 95 mm 3 /year, approximately one-third greater than more contemporary studies of wear in primary THA, which report values of 55 to 71 mm 3 /year for conventional polyethylene and 14 to 17 mm 3 /year for highly crosslinked polyethylene using 28-mm and 32-mm heads [4,10,11,22,27]. This would appear to support the claim of some investigators that the wear rate of constrained cups is higher than unconstrained devices of the same head diameter [1,2,18,31].…”

Section: Discussionmentioning

confidence: 77%

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Constrained Cups Appear Incapable of Meeting the Demands of Revision THA

Noble

Durrani

Usrey

et al. 2012

Clinical Orthopaedics &Amp; Related Research

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Background Failure rates of constrained cups for treating recurrent dislocation in revision THA range from 40% to 100%. Although constrained liners are intended to stabilize the hip by mechanically preventing dislocation, the resulting loss of range of motion may lead to impingement and, ultimately, implant failure. Questions/purposes We therefore documented the mechanisms of failure of constrained acetabular cups in revision THA and determined the type and severity of damage (wear, fracture, and impingement) that occurs in situ.Methods We retrieved 57 constrained components of four different designs at revision THA and examined for the presence of rim impingement, oxidation, cracks within the liner, backside wear, pitting, scratching, abrasion, burnishing, and the presence of embedded particles. Articular wear was calculated from the volume of the concave articular bearing surface, which was measured using the fluid displacement method. Results Failure of the locking ring was responsible for 51% of failures, whereas 28% of revisions were the result of acetabular cup loosening, 6% backside wear, and 22% infection. Impingement damage of the rim of the polyethylene liner was seen in all retrievals with moderate or severe damage in 54%. The average volumetric wear rate of the articular surface was 95 mm 3 /year. Conclusions Failure of the locking liner ring and loosening of the acetabular cup are the primary causes of mechanical failure with constrained liners; polyethylene is an inadequate material for restricting motion of the hip to prevent instability. The durability of these devices is unlikely to improve unless the mechanical demands are modified through increased range of motion leading to less frequent rim impingement.

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Section: Discussionmentioning

confidence: 77%

“…Rim impingement damage was defined by the formation of a blunted edge on the rim of the component as seen on visual and stereomicroscopic examination [21,44]. The severity of impingement damage was classified as none, mild, moderate, or severe according to the 4-point grading system of Birman et al [4].…”

Section: Depuy S-rommentioning

confidence: 99%

Constrained Cups Appear Incapable of Meeting the Demands of Revision THA

Noble

Durrani

Usrey

et al. 2012

Clinical Orthopaedics &Amp; Related Research

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“…Wroblewski [32] found impingement in 14 of 22 retrieved Charnley sockets (64%), while Birman et al [1] noted 32% and Shon et al [25] found 56%. Among the latter's findings was that 94% of those revised for recurrent dislocation had impingement, and in their overall group, 41% had impingement, despite more than 1 .…”

Section: Evidence For Edge Loading In Mop Thamentioning

confidence: 99%

Edge Loading Has a Paradoxical Effect on Wear in Metal-on-Polyethylene Total Hip Arthroplasties

Harris

2012

Clinical Orthopaedics &Amp; Related Research

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Background Edge wear is an adverse factor that can negatively impact certain THAs. In some metal-on-metal THAs, it can lead to adverse tissue reactions including aseptic lymphocytic vasculitis-associated lesions and even to pseudotumor formation. In some ceramic-on-ceramic THAs, it can lead to squeaking and/or stripe wear. Edge wear in metal-on-metal and ceramic-on-ceramic THAs can also be associated with accelerated wear across the articulation of these joints. Questions/purposes I asked: Does edge wear occur in metal-on-polyethylene (MOP) articulations? And if so, does it increase joint wear? Methods I examined the evidence in the literature for edge wear occurring in MOP THA and then assessed the evidence in the literature for data supporting the concept that edge wear in MOP hips could accelerate wear across the articulation over time.

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“…At the same time, re-crystallisation was hindered by the newly formed crosslinks, the crystallinity was reduced and therefore the fatigue strength of radiation crosslinked UHMWPE was further reduced [53]. The in vitro wear rate [47] and the penetration rates of re-melted UHMWPE in the intermediate term (five years) have been very low [22,45], but there are some concerns about the increased incidence of rim fracture under impingement and adverse loading conditions due to the lowered fatigue strength of this material [6,27,70].…”

Section: Introductionmentioning

confidence: 99%

Vitamin E diffused, highly crosslinked UHMWPE: a review

Oral

Muratoglu

2010

International Orthopaedics (SICOT)

212

133

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Highly crosslinked UHMWPE has become the bearing surface of choice in total hip arthroplasty. First generation crosslinked UHMWPEs, clinically introduced in the 1990s, show significant improvements compared to gamma sterilised, conventional UHMWPE in decreasing wear and osteolysis. These crosslinked UHMWPEs were thermally treated (annealed or melted) after irradiation to improve their oxidation resistance. While annealing resulted in the retention of some oxidation potential, postirradiation melted UHMWPEs had reduced fatigue strength due to the crystallinity loss during melting. Thus, the stabilisation of radiation crosslinked UHMWPEs by the diffusion of the antioxidant vitamin E was developed to obtain oxidation resistance with improved fatigue strength by avoiding post-irradiation melting. A two-step process was developed to incorporate vitamin E into irradiated UHMWPE by diffusion to obtain a uniform concentration profile. Against accelerated and real-time aging in vitro, this material showed superior oxidation resistance to UHMWPEs with residual free radicals. The fatigue strength was improved compared to irradiated and melted UHMWPEs crosslinked using the same irradiation dose. Several adverse testing schemes simulating impingement showed satisfactory behaviour. Peri-prosthetic tissue reaction to vitamin E was evaluated in rabbits and any effects of vitamin E on device fixation were evaluated in a canine model, both of which showed no detrimental effects of the inclusion of vitamin E in crosslinked UHMWPE. Irradiated, vitamin E-diffused, and gamma sterilised UHMWPEs have been in clinical use in hips since 2007 and in knees since 2008. The clinical outcome of this material will be apparent from the results of prospective, randomised clinical studies. IntroductionOsteolysis triggered mainly by ultrahigh molecular weight polyethylene (UHMWPE) wear particles has been one of the major problems in total hip arthroplasty along with instability/dislocation and infection [7]. Highly crosslinked UHMWPEs were developed using high-dose irradiation (50-100 kGy) to decrease the wear rate of UHMWPE [44,46] and have become the standard-of-care after their first decade of service, especially in North America [61].Irradiation causes crosslinking in the amorphous phase of the UHMWPE [33], but also initiates the formation of free radicals in the crystalline phase [23], unable to recombine due to structural limitations, they become trapped for long periods of time [29]. These residual free radicals are believed to migrate to the crystalline/amorphous interface and cause oxidative degradation in the material [16][17][18]59, 69] through a cascade of reactions with oxygen [32,71].In first generation crosslinked UHMWPEs [34], postirradiation thermal treatment was used to increase the oxidation resistance (Fig. 1). One approach was to annealThe studies discussed here were performed by research funding in part from NIH/NIAMS

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Cracking and Impingement in Ultra–High-Molecular-Weight Polyethylene Acetabular Liners

Cited by 56 publications

References 15 publications

Constrained Cups Appear Incapable of Meeting the Demands of Revision THA

Constrained Cups Appear Incapable of Meeting the Demands of Revision THA

Edge Loading Has a Paradoxical Effect on Wear in Metal-on-Polyethylene Total Hip Arthroplasties

Vitamin E diffused, highly crosslinked UHMWPE: a review

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