Analysis of Crosslinked and Conventional Polyethylene Explants

This study is enrolling participants by invitation only.
Sponsor:
Collaborators:
Orthopaedic Biomechanics and Biomaterials Laboratory at Massachusetts General Hospital
DePuy Orthopaedics
Information provided by (Responsible Party):
Anderson Orthopaedic Research Institute
ClinicalTrials.gov Identifier:
NCT01484002
First received: November 28, 2011
Last updated: January 23, 2013
Last verified: January 2013
  Purpose

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.


Condition Intervention
Osteoarthritis
Device: Total hip arthroplasty

Study Type: Observational
Study Design: Observational Model: Cohort
Time Perspective: Retrospective
Official Title: Collaborative Analysis of UHMWPE Explants: Conventional UHMWPE With No Radiation and Marathon

Resource links provided by NLM:


Further study details as provided by Anderson Orthopaedic Research Institute:

Primary Outcome Measures:
  • Oxidation levels [ Time Frame: At an average of 5 years in vivo ] [ Designated as safety issue: No ]
    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.


Secondary Outcome Measures:
  • Absorbed lipids [ Time Frame: At an average of 5 years in vivo ] [ Designated as safety issue: No ]
    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 ] [ Designated as safety issue: No ]
    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 ] [ Designated as safety issue: No ]
    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 ] [ Designated as safety issue: No ]
    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 ] [ Designated as safety issue: No ]
    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 ] [ Designated as safety issue: No ]
    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 ] [ Designated as safety issue: No ]
    Infra-red crystallinity will be evaluated with FTIR after hexane extraction.

  • Gel content [ Time Frame: At an average of 5 years in vivo ] [ Designated as safety issue: No ]
    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.


Estimated Enrollment: 60
Study Start Date: December 2011
Estimated Study Completion Date: December 2013
Estimated Primary Completion Date: December 2013 (Final data collection date for primary outcome measure)
Groups/Cohorts Assigned Interventions
Crosslinked polyethylene liners
Polyethylene liners from joint replacements that were crosslinked and heat treated to eliminate free radicals.
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
Conventional polyethylene liners
Polyethylene liners from joint replacements that manufactured from conventional UHMWPE and terminally sterilized by methods that did not involve gamma-irradiation.
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

Detailed Description:

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.

  Eligibility

Ages Eligible for Study:   18 Years and older
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   No
Sampling Method:   Non-Probability Sample
Study Population

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.

Criteria

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
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT01484002

Locations
United States, Massachusetts
Orthopaedic Biomechanics and Biomaterials Laboratory at Massachusetts General Hospital
Boston, Massachusetts, United States, 02114
United States, Virginia
Anderson Orthopaedic Research Institute
Alexandria, Virginia, United States, 22306
Sponsors and Collaborators
Anderson Orthopaedic Research Institute
Orthopaedic Biomechanics and Biomaterials Laboratory at Massachusetts General Hospital
DePuy Orthopaedics
Investigators
Study Director: Robert H Hopper, Jr., PhD Anderson Orthopaedic Research Institute
  More Information

Additional Information:
Publications:
Responsible Party: Anderson Orthopaedic Research Institute
ClinicalTrials.gov Identifier: NCT01484002     History of Changes
Other Study ID Numbers: AORI2011-0101, MGH Agreement No: A208947
Study First Received: November 28, 2011
Last Updated: January 23, 2013
Health Authority: United States: Institutional Review Board

Keywords provided by Anderson Orthopaedic Research Institute:
Hip replacement
Crosslinked and conventional polyethylene
Oxidation
Crosslink density
Outcome

Additional relevant MeSH terms:
Osteoarthritis
Arthritis
Joint Diseases
Musculoskeletal Diseases
Rheumatic Diseases

ClinicalTrials.gov processed this record on September 18, 2014