ASTM_F_2777_-_10.pdf

Designation:F277710Standard Test Method forEvaluating Knee Bearing(Tibial Insert)Endurance andDeformation Under High Flexion1This standard is issued under the fixed designation F2777;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This standard specifies a test method for determining theendurance properties and deformation,under specified labora-tory conditions,of ultra high molecular weight polyethylene(UHMWPE)tibial bearing components used in bicompartmen-tal or tricompartmental knee prosthesis designs.1.2 This test method is intended to simulate near posterioredge loading similar to the type of loading that would occurduring high flexion motions such as squatting or kneeling.1.3 Although the methodology described attempts to iden-tify physiological orientations and loading conditions,theinterpretation of results is limited to an in vitro comparisonbetween knee prosthesis designs and their ability to resistdeformation and fracture under stated test conditions.1.4 This test method applies to bearing components manu-factured from UHMWPE.1.5 This test method could be adapted to address unicom-partmental total knee replacement(TKR)systems,providedthat the designs of the unicompartmental systems have suffi-cient constraint to allow use of this test method.This testmethod does not include instructions for testing two unicom-partmental knees as a bicompartmental system.1.6 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.7 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2F1223 Test Method for Determination of Total Knee Re-placement ConstraintF2003 Practice for Accelerated Aging of Ultra-High Mo-lecular Weight Polyethylene after Gamma Irradiation inAirF2083 Specification for Knee Replacement Prosthesis2.2 Other Standards:3ISO 4965 Axial Load Testing MachinesDynamic ForceCalibrationStrain Gauge TechniqueISO 5833 Implants for SurgeryAcrylic Resin Cements3.Terminology3.1 Definitions:3.1.1 anatomic(mechanical)axis of the femurthe linebetween the center of the femoral head and the center of thefemoral knee.3.1.2 bearing centerlinethe line running anteroposteriorthat is the mirror line of the femoral articulating surface.Forasymmetric bearing tibial tray designs,the appropriate tibialtray centerline shall be determined and reported along with therationale for the location.3.1.3 bearing retention mechanismmechanical means forpreventing tibial tray/bearing disassociation.3.1.4 femoral component centerlinea line running antero-posterior between the femoral condyles and parallel to thefemoral condyles.The line should be equidistant between thecondyles.For asymmetric or non parallel condyles designs,theappropriate centerline shall be determined,and the rationale forthat location reported.1This test method is under the jurisdiction ofASTM Committee F04 on Medicaland Surgical Materials and Devices and is the direct responsibility of SubcommitteeF04.22 on Arthroplasty.Current edition approved Sept.15,2010.Published October 2010.DOI:10.1520/F2777-10.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.1.5 fixed bearing systema knee prosthesis system com-prised of a femoral component and a tibial component,wherethe tibial articulating surface is not intended to move relative tothe tibial tray.3.1.6 mobile bearingthe component between fixed femo-ral and tibial knee components with an articulating surface onboth the inferior and superior sides.3.1.7 mobile bearing knee systema knee prosthesis systemcomprised of a femoral component,a tibial component,and amobile bearing component that can rotate and/or translaterelative to the tibial component.3.1.8 posterior slopethe angle that the perpendicular axisof the tibial tray makes when it is tilted posteriorly away fromthe tibial axis(see Fig.1).3.1.9 R valuethe ratio of the minimum force to themaximum force(that is,R=minimum force/maximum force).3.1.10 tibial axisnominal longitudinal axis of the tibia,which corresponds with the central axis of the medullary cavityof the proximal tibia.3.1.11