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Analysis of Crosslinked and Conventional Polyethylene Explants

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ClinicalTrials.gov Identifier: NCT01484002
Recruitment Status : Enrolling by invitation
First Posted : December 2, 2011
Last Update Posted : January 24, 2017
Sponsor:
Collaborators:
Orthopaedic Biomechanics and Biomaterials Laboratory at Massachusetts General Hospital
DePuy Orthopaedics
Information provided by (Responsible Party):
Anderson Orthopaedic Research Institute

November 28, 2011
December 2, 2011
January 24, 2017
December 2011
December 2017   (Final data collection date for primary outcome measure)
Oxidation levels [ Time Frame: At an average of 5 years in vivo ]
Polyethylene oxidation levels will be quantified as a function of depth away from the articular and rim surfaces using Fourier Transform Infrared Spectroscopy (FTIR). Pre and post-hexane and nitric oxide (NO) exposed post-hexane thin sections will be analyzed.
Same as current
Complete list of historical versions of study NCT01484002 on ClinicalTrials.gov Archive Site
  • Absorbed lipids [ Time Frame: At an average of 5 years in vivo ]
    Absorbed lipids will be evaluated by determining the level of carbonyls before and after hexane extraction using Fourier Transform Infrared Spectroscopy (FTIR).
  • Crosslink density [ Time Frame: At an average of 5 years in vivo ]
    Crosslink density will be evaluated using the gravimetric method on thin sections (~300μm) cut co-planar to the articular surfaces.
  • Differential Scanning Calorimeter (DSC) [ Time Frame: At an average of 5 years in vivo ]
    Differential Scanning Calorimeter (DSC) will be used to determine the 1st and 2nd heats, and 1st cool crystallinity, peak melting/crystallization points.
  • Hydroperoxides [ Time Frame: At an average of 5 years in vivo ]
    Hydroperoxides will be evaluated with FTIR by NO treatment after hexane extraction.
  • Vinyl end-groups [ Time Frame: At an average of 5 years in vivo ]
    Vinyl end-groups will be evaluated with FTIR after hexane extraction to quantify chain scission.
  • Trans vinylene (TVI) unsaturations [ Time Frame: At an average of 5 years in vivo ]
    Trans vinylene (TVI) unsaturations will be evaluated with FTIR after hexane extraction to determine radiation history and dose.
  • Crystallinity [ Time Frame: At an average of 5 years in vivo ]
    Infra-red crystallinity will be evaluated with FTIR after hexane extraction.
  • Gel content [ Time Frame: At an average of 5 years in vivo ]
    To quantify the extent of chain scission, gel content will be evaluated by measuring the non-extractable portion of the molecules using thin sections cut co-planar to the articular surfaces with a microtome and extracting the polyethylene chains from these sections in hot xylene.
Same as current
Not Provided
Not Provided
 
Analysis of Crosslinked and Conventional Polyethylene Explants
Collaborative Analysis of UHMWPE Explants: Conventional UHMWPE With No Radiation and Marathon
This retrospective study will investigate the changes that occur in ultrahigh molecular weight polyethylene (UHMWPE) implants that have been retrieved from joint replacement patients. Analysis techniques will include Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimeter (DSC) and crosslink density measurements. Crosslink density measurements will be evaluated as a function of distance away from the articular surface and the rim of the implant. Gel and hydroperoxide contents will also be evaluated. The objective is to characterize the in vivo and ex vivo changes that occur with cross-linked and conventional polyethylene bearings sterilized by methods that do not involve radiation. The investigators hypothesize that polyethylene absorbs lipids in vivo but experiences negligible oxidation or reductions in polymer crosslinking until it is explanted and stored at room temperature with access to ambient air.

For many years, gamma-irradiation in air was a common method for the terminal sterilization of ultrahigh molecular weight polyethylene (UHMWPE) materials used for joint replacement. A serendipitous byproduct of sterilization with gamma-irradiation was polymer crosslinking that tended to improve the wear performance of the polyethylene. During the 1990s, however, the orthopaedic community became aware that gamma-irradiation created free radicals within polyethylene, rendering the material susceptible to oxidative degradation. In view of this potentially deleterious effect, terminal sterilization methods using chemical surface treatments were developed to avoid free radical formation. To induce polyethylene crosslinking without residual free radicals, manufacturers also developed methods to crosslink the polyethylene followed by heat treatments to eliminate free radicals. These crosslinked materials were introduce during the latter part of the 1990s and clinical outcome studies among hip replacement patients have demonstrated substantially reduced wear at early follow-up intervals based on radiographic measurements. However, the long-term performance of crosslinked polyethylene is unknown and some investigators have expressed concerns related to in vivo degradation. Additionally, some crosslinked UHMWPE components have shown high levels of oxidation and chain scission after removal from patients and storage in air. Among these implants, it is unknown whether the oxidation and chain scission occurred during implantation or after the polyethylene was removed from the patient.

This study will characterize the material properties of polyethylene liners retrieved from hip replacement patients. The study population will include crosslinked and conventional UHMWPE liners that were terminally sterilized without the use of radiation. To quantify the potential effects of different storage methods, liners that were vacuum packed and frozen after retrieval and others that were stored at room temperature with access to ambient light and air following explantation will be included in the study population. Analysis techniques will include Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimeter (DSC) and crosslink density measurements. Crosslink density measurements will be evaluated as a function of distance away from the articular surface and the rim of the implant. Gel and hydroperoxide contents will also be evaluated. The goal of the analysis is to better understand the changes in polyethylene material properties that occur in vivo and ex vivo.

Observational
Observational Model: Cohort
Time Perspective: Retrospective
Not Provided
Not Provided
Non-Probability Sample
Crosslinked and conventional polyethylene liners terminally sterilized without gamma-irradiation will be used for this study. Specimens will be selected from the implant retrieval collection maintained by the Anderson Orthopaedic Research Institute.
Osteoarthritis
Device: Total hip arthroplasty
Replacement of a patient's native hip with an artificial implant featuring a metal-on-polyethylene articulation
Other Names:
  • DePuy Marathon crosslinked polyethylene
  • DePuy Enduron conventional polyethylene
  • Crosslinked polyethylene liners
    Polyethylene liners from joint replacements that were crosslinked and heat treated to eliminate free radicals.
    Intervention: Device: Total hip arthroplasty
  • Conventional polyethylene liners
    Polyethylene liners from joint replacements that manufactured from conventional UHMWPE and terminally sterilized by methods that did not involve gamma-irradiation.
    Intervention: Device: Total hip arthroplasty

*   Includes publications given by the data provider as well as publications identified by ClinicalTrials.gov Identifier (NCT Number) in Medline.
 
Enrolling by invitation
60
Same as current
December 2017
December 2017   (Final data collection date for primary outcome measure)

Inclusion Criteria:

  • Retrieved total hip arthroplasty liners maintained by the Anderson Orthopaedic Research Institute
  • Crosslinked or conventional liners terminally sterilized without gamma-irradiation

Exclusion Criteria:

  • Liners terminally sterilized with gamma-irradiation
Sexes Eligible for Study: All
18 Years and older   (Adult, Older Adult)
No
Contact information is only displayed when the study is recruiting subjects
United States
 
 
NCT01484002
AORI2011-0101
MGH Agreement No: A208947 ( Other Grant/Funding Number: DePuy Orthopaedics, Inc. )
No
Not Provided
Not Provided
Anderson Orthopaedic Research Institute
Anderson Orthopaedic Research Institute
  • Orthopaedic Biomechanics and Biomaterials Laboratory at Massachusetts General Hospital
  • DePuy Orthopaedics
Study Director: Robert H Hopper, Jr., PhD Anderson Orthopaedic Research Institute
Anderson Orthopaedic Research Institute
January 2017