STP859: Loosening of Well-Cemented Total-Hip Femoral Prosthesis Due to Creep of the Cement

    Ebramzadeh, E
    Research engineer and research assistant, Orthopaedic Biomechanics Laboratory, Orthopaedic Hospital-University of Southern California, Los Angeles, CA

    Mina-Araghi, M
    Research engineer and research assistant, Orthopaedic Biomechanics Laboratory, Orthopaedic Hospital-University of Southern California, Los Angeles, CA

    Clarke, IC
    Associate professordirector, University of Southern CaliforniaOrthopaedic Biomechanics Laboratory, Orthopaedic Hospital-University of Southern California, Los Angeles, CA

    Ashford, R
    Research assistant, Medical School, Orthopaedic Hospital-University of Southern California, Los Angeles, CA

    Pages: 27    Published: Jan 1985


    Abstract

    A review of previous publications on the mechanical complications of cemented total-hip prosthesis femoral component indicates several failure mechanisms. However, the biomechanical significance of the various reported radiographic phenomena has not been clearly assessed with static testing or with computer models.

    A new technique was developed to directly measure internal cement strains in a simulated proximal femur with cemented femoral total-hip prostheses. Static experimental testing of a Delrin plastic-bone-analog with a cemented metallic femoral prosthesis indicated highest cement strains in the proximal-medial aspect of the cement sheath, which correlated with highest cement stresses in the same location in a corresponding finite-element analysis computer model. The most noticeable observation from the cyclic testing was the 73% decrease of cement strains in the proximal-medial region after 4.1 million cycles. This time-dependent behavior, that is, creep, may have significance in the failure mechanisms of cemented femoral total-hip replacement components and should be considered in future static or cyclic experimental testing and computer modeling of such prosthetic components.

    Keywords:

    implant materials, biological degradation, fatigue (materials), total-hip replacement, femoral prosthesis, cement stresses, radiolucent zones, loosening, stainless steel, titanium alloys, cobalt-chrome alloys


    Paper ID: STP33265S

    Committee/Subcommittee: F04.42

    DOI: 10.1520/STP33265S


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