STP918

    Failure Analysis of a Total Hip Femoral Component: A Fracture Mechanics Approach

    Published: Jan 1986


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    Abstract

    Failure analysis was conducted on 21 fractured femoral components from Trapezoidal-28 total hip replacements performed at The Hospital for Special Surgery. These components were made from 316L stainless steel and had a trapezoidally shaped cross section in the neck and stem portions. Fractographic examination revealed multiple cracks on the medial side of the stems and a fracture surface with crack initiation sites from both the medial and lateral surfaces. Electron microscopy revealed striations on the fracture surfaces of both medial and lateral cracks, indicating that crack growth occurred by a fatigue fracture process in both cases. Analytical examination using curved beam theory with a bilinear stress-strain relationship predicted the medial cracks to initiate first, due to residual tensile stresses following an overload. In the presence of a medial crack, higher tensile stresses were predicted on the lateral side, making it the next most likely site for crack initiation. Fracture occurred when a lateral crack joined with a pre-existing medial crack. It was concluded this fracture mode was due to the combined effects of the trapezoidal stem design and the mechanical properties of 316L stainless steel.

    Keywords:

    total hip replacement, femoral component, failure analysis, fatigue, fracture mechanics, residual stress


    Author Information:

    Rimnac, CM
    Assistant scientist, associate scientist, associate scientist, and director, The Hospital for Special SurgeryThe New York Hospital and Cornell University Medical College, New York, NY

    Wright, TM
    Assistant scientist, associate scientist, associate scientist, and director, The Hospital for Special SurgeryThe New York Hospital and Cornell University Medical College, New York, NY

    Bartel, DL
    Assistant scientist, associate scientist, associate scientist, and director, The Hospital for Special SurgeryThe New York Hospital and Cornell University Medical College, New York, NY

    Burstein, AH
    Assistant scientist, associate scientist, associate scientist, and director, The Hospital for Special SurgeryThe New York Hospital and Cornell University Medical College, New York, NY


    Paper ID: STP19344S

    Committee/Subcommittee: E08.08

    DOI: 10.1520/STP19344S


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