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    Volume 8, Issue 5 (May 2011)

    In Vitro Knee Wear, Kinematics, and Particle Morphology Among Different Bearing Geometries in a Mobile Bearing Knee System

    (Received 24 August 2010; accepted 28 March 2011)

    Published Online: 2011


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    Excellent clinical long term results were reported from individual clinical centers for both of the two fundamental design principles—fixed and mobile bearing knee designs. Several pre-clinical studies are dealing with a direct comparison between fixed and mobile bearing knee replacements, but to our knowledge there is no published data comparing the in vitro wear and kinematic behaviour of mobile bearing designs with floating, rotating and posterior stabilized gliding surfaces. The objective of our study was to evaluate the influence of the tibio-femoral bearing type on abrasive wear, tibio-femoral kinematics and particle release for a mobile bearing knee system with three different design alternatives. Wear simulator testing on 12 e.motion® TKA devices (Aesculap, Germany) was performed according to ISO 14243-1. The knee replacements were tested for 5 million cycles on a customized 4 station knee wear simulator (Endolab, Germany) in the bearing configurations floating platform (FP), ultra-concruent rotating platform (UC) and posterior stabilized (PS). The amount of wear in the polyethylene gliding surfaces was estimated to 4.4±0.9 mg/million cycles (FP design) to 2.3±0.1 mg/million cycles (UC) and 5.2±1.0 mg/million cycles (PS). The amplitudes of A/P displacement during 5 million cycles showed a mean value of 3.7±0.33 mm (FP design), 2.3±0.14 mm (UC) and 2.9±0.26 mm (PS). For the I/E rotation angle, the amplitudes of the recorded mean values were 6.3°±0.82° (FP design), 3.7±0.41° (UC) and 4.9°±0.48° (PS). The polyethylene particle release (mean size and morphology) is comparable for the mobile bearing articulations FP, UC, and PS. The present study demonstrates the influence of different mobile bearing types on abrasive wear, tibio-femoral kinematics, and particle release under elimination of bearing material influences.

    Author Information:

    Grupp, T. M.
    Aesculap AG Research and DevelopmentLudwig Maximilian University Clinic for Orthopaedic Surgery, Campus Grosshadern, TuttlingenMunich,

    Miehlke, R. K.
    Knee Division, The Rhine-Main Centre for Joint DiseasesKnee Division, The Muensterland Centre for Joint Diseases, WiesbadenMuenster,

    Hintner, M.
    Endolab Mechanical Engineering GmbH, Thansau,

    Schwiesau, J.
    Aesculap AG Research and Development, Tuttlingen,

    Kaddick, C.
    Endolab Mechanical Engineering GmbH, Thansau,

    Stock #: JAI103304


    DOI: 10.1520/JAI103304

    Title In Vitro Knee Wear, Kinematics, and Particle Morphology Among Different Bearing Geometries in a Mobile Bearing Knee System
    Symposium ,
    Committee F04