Impact of gamma sterilization on clinical performance of polyethylene in the knee

Collier, John; Sperling, Daniel K.; Currier, John H.; Sutula, Lauren C.; Saum, Kenneth A.; Mayor, Michael B.

doi:10.1016/s0883-5403(96)80026-x

Cited by 257 publications

(134 citation statements)

References 12 publications

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“…On the one hand, the crosslinking imparted by a single sterilization dose (25-40 kGy) of gamma radiation substantially improved its wear resistance [29,55] and contributed to the long-term clinical success of the metal-on-polyethylene wear couple used in hip and knee arthroplasty to this day. Gamma sterilization in the presence of air also had a drawback in that it rendered the polymer vulnerable to oxidation before implantation [81,113] and during in vivo exposure [30,36,78,82,129]. It would take decades, however, for gamma sterilization in air to be challenged as the industry standard for polyethylene, because the deleterious effects of oxidation in polyethylene take many years to manifest [81].…”

Section: History and Development Of Hxlpementioning

confidence: 99%

History and Systematic Review of Wear and Osteolysis Outcomes for First-generation Highly Crosslinked Polyethylene

Kurtz

Gawel

Patel

2011

Clinical Orthopaedics &Amp; Related Research

411

282

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Background Highly crosslinked polyethylene (HXLPE) was introduced to reduce wear and osteolysis in total joint arthroplasty. While many studies report wear and osteolysis associated with HXLPE, analytical techniques, clinical study design and followup, HXLPE formulation and implant design characteristics, and patient populations differ substantially among investigations, complicating a unified perspective. Questions/purposes Literature on first-generation HXLPE was summarized. We systematically reviewed the radiographic wear data and incidence of osteolysis for HXLPE in hip and knee arthroplasty. Methods PubMed identified 391 studies; 28 met inclusion criteria for a weighted-averages analysis of two-dimensional femoral head penetration rates. To determine the incidence of osteolysis, we estimated a pooled odds ratio using a random-effects model.Results Weighted-averages analyses of femoral head penetration rates in HXLPE liners and conventional UHMWPE liners resulted, respectively, in a mean twodimensional linear penetration rate of 0.042 mm/year based on 28 studies (n = 1503 hips) and 0.137 mm/year based on 18 studies (n = 695 hips). The pooled odds ratio for the risk of osteolysis in HXLPE versus conventional liners was 0.13 (95% confidence interval, 0.06-0.27) among studies with minimum 5-year followup. We identified two clinical studies of HXLPE in TKA, preventing systematic analysis of outcomes. Conclusions HXLPE liner studies consistently report lower femoral head penetration and an 87% lower risk of osteolysis. Reduction in femoral head penetration or osteolysis risk is not established for large-diameter ([ 32 mm) metallic femoral heads or ceramic femoral heads of any size. Few studies document the clinical performance of HXLPE in knees.

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Section: History and Development Of Hxlpementioning

confidence: 99%

History and Systematic Review of Wear and Osteolysis Outcomes for First-generation Highly Crosslinked Polyethylene

Kurtz

Gawel

Patel

2011

Clinical Orthopaedics &Amp; Related Research

411

282

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“…Shelf storage time before implantation was a concern for gamma-air-sterilized inserts [4,7,9] where shelf oxidation led to early in vivo fatigue damage. Some early barrier packaging did not effectively prevent shelf oxidation [6], but the change from gamma-air to gamma-inert sterilization largely prevented the shelf oxidation that led to fatigue after less than 4 years in vivo [5]. In vivo oxidation was predicted to increase exponentially with time [9,12].…”

Section: Discussionmentioning

confidence: 99%

“…Thin sections were prepared using a technique developed to permit static mechanical testing of the surface, subsurface, and bulk regions of the tibial bearings [5]. Two sagittal cuts, 6 mm apart, were made from the anterior to the posterior surface of the tibial bearings using a band saw.…”

Section: Methodsmentioning

confidence: 99%

“…Two sagittal cuts, 6 mm apart, were made from the anterior to the posterior surface of the tibial bearings using a band saw. Thin sections (200 lm thick) of these specimens were cut parallel to the nonarticular surface using a Jung microtome (Leica Microsystems, Wetzlar, Germany), producing a series of horizontal sections [5]. A sequence of thin sections representing a depth of approximately 4 mm (20 sections) was taken from each sample.…”

Section: Methodsmentioning

confidence: 99%

“…In the mid to late 1990s, manufacturers changed from gamma sterilization in air (gamma-air) to gamma sterilization in an inert environment (gamma-inert; eg, ArCom 1 , gamma vacuum foil, gamma-N2, etc). This change was an effort to exclude oxygen from the sterilization environment after reports showing gamma-air sterilization initiated UHMWPE oxidation [5,14]. Long shelf aging time of gammaair-sterilized bearings before implantation reportedly led to reduced mechanical properties of UHMWPE, resulting in early fatigue damage, especially in tibial inserts [7].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Gamma-irradiation Sterilization in an Inert Environment: A Partial Solution

Berry

Currier

Mayor

et al. 2012

Clinical Orthopaedics &Amp; Related Research

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Background In the mid to late 1990s, to sterilize UHMWPE bearings, manufacturers changed from gammairradiation-in-air (gamma-air) sterilization, which initiated oxidation leading to bearing fatigue, to gamma-irradiation sterilization in an inert environment (gamma-inert). The change to gamma-inert sterilization reportedly prevented shelf oxidation before implantation but not in vivo oxidation. Questions/purposes We asked: (1) Has the change to gamma-inert sterilization prevented shelf oxidation that led to early in vivo fatigue damage in gamma-air-sterilized tibial inserts? And (2) has the change to gamma-inert sterilization prevented the occurrence of fatigue secondary to in vivo oxidation? Methods We rated 183 retrieved gamma-air-and 175 retrieved gamma-inert-sterilized tibial inserts for clinical fatigue damage and analyzed 132 gamma-air-and 174 gamma-inert-sterilized tibial inserts for oxidation by Fourier transform infrared spectroscopy. Results Oxidation led to decreased mechanical properties in shelf-aged gamma-air-sterilized tibial inserts. Barrier packaging prevented shelf oxidation in gamma-inertsterilized tibial inserts. Gamma-air-and gamma-inertsterilized inserts oxidized in vivo. Fatigue damage (delamination) occurred more frequently in inserts retrieved after longer time in vivo. Longer in vivo time correlated with higher oxidation and more accumulated cycles of use. Conclusions Published oxidation projections suggest gamma-inert-sterilized tibial inserts would reach the critical oxidation for the onset of fatigue after 11 to 14 years in vivo. These retrievals appear to follow the projected oxidation trends. Frequency of fatigue damage increased with increasing oxidation. Clinical Relevance Fatigue of tibial inserts becomes more likely, especially in active patients, after more than a decade of good clinical performance.

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Subsurface oxidation of polyethylene

Daly

Yin

1998

J. Biomed. Mater. Res.

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Since the 1960s ultrahigh molecular weight polyethylene has been a primary bearing material in orthopedic prostheses. Most polyethylene components have been sterilized by exposure to gamma radiation, but in the presence of oxygen this promotes degradation and correlates with component failure in the body. To better understand the mechanism of degradation, we measured oxidation profiles for components shelf aged 5.8 and 10.9 years. Microtomed sections from each component were analyzed for ketones, which are the primary oxidation products, by FTIR spectroscopy. Maximum ketone concentrations in both cases were found several millimeters below the surface. We propose a model to explain the profiles. Alkyl radicals, which are uniformly generated in the polyethylene during irradiation, react with peroxyl radicals, which are produced by alkyl radicals with oxygen to form ketones. At the component surface ketone levels are low because high oxygen concentrations deplete alkyl radicals, creating an excess of peroxyl radicals. In the bulk material ketones are low because low oxygen concentrations limit the formation of peroxyl radicals. However, just below the surface the concentrations of alkyl and peroxyl radicals balance, promoting ketone production. A computer simulation that accounts for the coupling of these reactions with the diffusion of oxygen shows a good agreement with the measured profiles.

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Impact of gamma sterilization on clinical performance of polyethylene in the knee

Cited by 257 publications

References 12 publications

History and Systematic Review of Wear and Osteolysis Outcomes for First-generation Highly Crosslinked Polyethylene

History and Systematic Review of Wear and Osteolysis Outcomes for First-generation Highly Crosslinked Polyethylene

Gamma-irradiation Sterilization in an Inert Environment: A Partial Solution

Subsurface oxidation of polyethylene

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