Tribological and Metal Ion Issues   |    
Tribological Considerations in Primary and Revision Metal-on-Metal Arthroplasty
Reginald Lee, MS1; Aaron Essner, MS1; Aiguo Wang, PhD1
1 Stryker Orthopaedics, 325 Corporate Drive, Mahwah, NJ 07430. E-mail address for R. Lee: Reginald.Lee@Stryker.com
View Disclosures and Other Information
Disclosure: The authors did not receive any outside funding or grants in support of their research for or preparation of this work. One or more of the authors, or a member of his or her immediate family, received, in any one year, payments or other benefits in excess of $10,000 or a commitment or agreement to provide such benefits from a commercial entity (Stryker Orthopaedics and Corin Medical Ltd.). No commercial entity paid or directed, or agreed to pay or direct, any -+benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the authors, or a member of their immediate families, are affiliated or associated.

The Journal of Bone and Joint Surgery, Inc.
J Bone Joint Surg Am, 2008 Aug 01;90(Supplement 3):118-124. doi: 10.2106/JBJS.H.00531
5 Recommendations (Recommend) | 3 Comments | Saved by 3 Users Save Case


Background: Metal-on-metal hip bearings undergo biphasic wear, starting with a short period of high wear (bedding-in) and followed by low steady-state wear. Bedding-in is the process by which the cup wears locally to conform to the geometry of the head. This process reduces the maximum contact stress and allows for appropriate lubrication. A critical area of conformance and wear is required for the bearing to reach a low steady-wear state. Cups were analyzed in this study after primary and revision wear scenarios to determine this critical area for this specific bearing.

Methods: Forty and 56-mm cobalt-chromium resurfacing bearings with 150 and 400-µm clearances were wear tested in a hip simulator for 5 million cycles. The cups underwent an additional 5 million cycles of testing against new heads, simulating a revision scenario. The revision heads were manufactured to cause the highest mismatch with the pre-worn cups, resulting in polar or local annular contact. Cup wear area was determined from weight-loss measurements after each phase of testing.

Results: All bearings experienced a biphasic wear performance with a short period of high wear followed by low steady-state wear. A consistent critical area of conformance was reached by all bearings after primary and revision testing conditions, regardless of bearing size, bearing clearance, or contact mode.

Conclusions: An area of conformity (wear) reduces contact pressures, is beneficial for lubrication, and is critical to reach a low steady-state wear rate. This study shows that this critical area is consistent regardless of bearing size, clearance, or contact mode. Bearing designs that allow the proper formation of this conformance area should bed-in and reach a low steady-state wear rate.

Clinical Relevance: The biphasic wear mode of metal-on-metal bearings has been shown clinically. Due to the unavoidable diametric deviations of femoral head implants, replacement of the femoral head in revision surgery may change the nature of the bearing contact and initiate a new bedding-in phase.

Figures in this Article


    metals ; arthroplasty
    Sign In to Your Personal ProfileSign In To Access Full Content
    Not a Subscriber?
    Get online access for 30 days for $35
    New to JBJS?
    Sign up for a full subscription to both the print and online editions
    Register for a FREE limited account to get full access to all CME activities, to comment on public articles, or to sign up for alerts.
    Register for a FREE limited account to get full access to all CME activities
    Have a subscription to the print edition?
    Current subscribers to The Journal of Bone & Joint Surgery in either the print or quarterly DVD formats receive free online access to JBJS.org.
    Forgot your password?
    Enter your username and email address. We'll send you a reminder to the email address on record.

    Forgot your username or need assistance? Please contact customer service at subs@jbjs.org. If your access is provided
    by your institution, please contact you librarian or administrator for username and password information. Institutional
    administrators, to reset your institution's master username or password, please contact subs@jbjs.org


    Accreditation Statement
    These activities have been planned and implemented in accordance with the Essential Areas and policies of the Accreditation Council for Continuing Medical Education (ACCME) through the joint sponsorship of the American Academy of Orthopaedic Surgeons and The Journal of Bone and Joint Surgery, Inc. The American Academy of Orthopaedic Surgeons is accredited by the ACCME to provide continuing medical education for physicians.
    CME Activities Associated with This Article
    Submit a Comment
    Please read the other comments before you post yours. Contributors must reveal any conflict of interest.
    Comments are moderated and will appear on the site at the discretion of JBJS editorial staff.

    * = Required Field
    (if multiple authors, separate names by comma)
    Example: John Doe

    Related Content
    The Journal of Bone & Joint Surgery
    JBJS Case Connector
    Topic Collections
    Related Audio and Videos
    PubMed Articles
    The treatment of glenohumeral joint osteoarthritis. -American Academy of Orthopaedic Surgeons (AAOS) | 9/11/2009
    Results provided by:
    Clinical Trials
    Readers of This Also Read...
    JBJS Jobs
    Pennsylvania - Penn State Milton S. Hershey Medical Center
    California - UCLA/OH Department of Orthopaedic Surgery