Convened under the auspicious of esteemed endorsers - ISTA

motion is separated from the transverse rotational motion onto two separate articulatingsurfaces, thus less cross-paths and less wear. Such expectations may have dominated thethinking and perhaps even clouded the expectations of TKR wear test engineers. Such wearreduction however has not really been categorically proven clinically.This paper combines in-vitro wear results from two separate laboratories, one in Nebraska USAand one in Germany. These two (industrially unattached labs) possess between them a verylarge set of in-vitro wear testing results across the widest variety of fixed and mobile bearingTKR designs. Fortunately, the wear testing methodology using the force-control regime used inthe two labs was largely similar, and was highly consistent within each lab. The fixed and themobile bearings were subjected to the exact same force fields, allowing their Anterior-Posteriortranslation and internal-external rotation kinematics to vary based on the individual TKRdesign.Tens of implant designs have been tested, both fixed and mobile, in total (bycondylar) form andunicompartmental, of various sizes. Some mobile bearings had rotating platforms and somewere rotating-translating. Some of the tests specifically compared mobile to fixed bearing tibialcomponents using identical femoral components. Between both labs, and across all tests, nostatistically significant difference resulted in wear between fixed and mobile bearings. Yet,such differences did clearly feature with known superior bearing materials (for wear) and otherfavored design features. Also, generally, the force-control test methodology has proven highlydiscriminatory in its simulation and measurement of wear as a potential clinical failure mode.The take home message to test engineers is to expect the wear of both mobile and fixedbearings to depend more on the detailed design and materials of the TKR than on the mobilityof the bearing. The results of this study re-confirm the need for wear testing to be performedprior to any clinical use on all implant designs, despite seemingly similar predicates or successof some mobile bearings.Friday, October 8, 2010, 16:30-17:30Session B15: MIS Techniques in TKAFatigue and Wear Evaluation of Partial Femoral and TibialUnicompartmental Cartilage Replacement Knee Components*Hani Haider - University of Nebraska Medical Center - Omaha, USAJoel Weisenburger - - ,Scott Sherman - Arthrex, Inc., - Naples, USAJosh Karnes - Arthrex Inc - Naples, USA- - ,*Email: hhaider@unmc.edufile:///E|/ISTA2010-Abstracts.htm[12/7/2011 3:15:47 PM]