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    STP1591

    Validating a Simplified Method for Assessing Total Hip Arthroplasty Taper Corrosion Susceptibility with a 15-Year Retrieval Database

    Published: 2016


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    Abstract

    Modular total hip arthroplasty (THA) implants allow tailoring a device to specific needs by adjusting head size, material, and offset. Modularity has recently been shown to increase risk of implant-related complications via mechanically assisted crevice corrosion (MACC). The purpose of this study was to establish a simple methodology based on existing standards to assess THA susceptibility to MACC. The method was validated by comparison to a 15-year retrieval database. CoCrMo heads were assembled onto Ti-6Al-4V stem tapers per ASTM F2009-00. The 12/14 tapers were prewet with a 1.5 pH solution. Approximately 7 mL of solution was used to create a sealed acidic microenvironment. The constructs were oriented at 10° of adduction and loaded according to ASTM F2068-03. Upon completion of 10 Mcycles, constructs were disassociated per ASTM F2009-00 and taper surfaces were scored using the Goldberg method. Microscopy was performed to evaluate damage. Four linear taper scans along the taper length in four quadrants of each femoral head were taken with a profilometer. Profile deviations represented the depths of material loss. Validation was assessed by comparing scores, visual features, and material loss values of tested components to those of retrieved implants. All tapers tested exhibited corrosion damage on the stem and head tapers. Evidence of wear scars, fretting, metal transfer, and corrosion debris were found. Measurable material loss occurred on all femoral head tapers. Stem machine lines transferred to the heads were found. This study used ASTM standards to reproduce MACC in an accelerated protocol. Results were consistent with published findings and a 15-year retrieval database. This database revealed MACC on worst-case samples of commonly used head diameters (<36 mm), with higher offsets having higher corrosion scores. Due to the similarities between the qualitative and quantitative assessments of tested specimens compared to worst-case retrieved implants, test methods presented here were validated.

    Keywords:

    taper corrosion, MACC, retrievals, fretting, Goldberg, femoral heads, modularity


    Author Information:

    Aldinger, Patrick
    Smith & Nephew Inc., Memphis, TN

    Cartner, Jacob
    Smith & Nephew Inc., Memphis, TN

    Jones, Bob
    Smith & Nephew Inc., Memphis, TN


    Committee/Subcommittee: F04.22

    DOI: 10.1520/STP159120140133