ASTM_F_2722_-_15.pdf

Designation:F272215Standard Practice forEvaluating Mobile Bearing Knee Tibial Baseplate RotationalStops1This standard is issued under the fixed designation F2722;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 practice covers a laboratory-based in vitro methodfor evaluating the mechanical performance of materials anddevices being considered for replacement of the tibio-femoraljoint in human knee joint replacement prostheses in mobilebearing knee systems.1.2 Mobile bearing knee systems permit internal externalrotation to take place on one or both articulating surfaces.Some designs place physical limits or stops to the amount ofrotation.Other designs may have increases of a resistance forcewith increases in rotation.1.3 Although the methodology describes attempts to iden-tify physiologically relevant motions and force conditions,theinterpretation of results is limited to an in vitro comparisonbetween mobile bearing knee designs and their ability tomaintain the integrity of the rotational stop feature and tibialbearing component under the stated test conditions.1.4 This practice is only applicable to mobile knee tibialsystems with a rotational stop.1.5 The values stated in SI units are regarded as standard.1.6 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:2F2083 Specification for Knee Replacement ProsthesisF2003 Practice for Accelerated Aging of Ultra-High Mo-lecular Weight Polyethylene after Gamma Irradiation inAir3.Terminology3.1 Definitions:3.1.1 bearing axisthe line connecting the lowest points onboth the lateral and medial condyles of the superior surface ofthe mobile bearing.3.1.2 inferior articulating interfacesany interface inwhich relative motion occurs between the underside of themobile bearing component and the tibial tray.3.1.3 mobile bearingthe component between fixed femo-ral and tibial knee components with an articulating surface onboth the inferior and superior sides.3.1.4 mobile bearing knee systema knee prosthesissystem,comprised of a tibial component,a mobile bearingcomponent that can rotate or rotate and translate relative to thetibial component,and a femoral component.3.1.5 neutral pointmidpoint of the bearing axis.3.1.6 rotational stopa feature that prevents relative rota-tion between two articulating joint surfaces beyond a specificangle of rotation or creates resistance to rotation beyond aspecific angel of rotation.3.1.7 superior articulating interfacesany interface inwhich relative motion occurs between the topside of the mobilebearing component and the femoral bearing component.4.Significance and Use4.1 Fundamental aspects of this practice include the use ofdynamic rotational force and motion representative of thehuman knee joint during an activity of daily living(deepflexion)and the effect of these forces and motions on thedesign features which stop or limit rotation in a mobile bearingknee design.4.2 This test is required if rotational stops are designed tolimit motion to 620 or less;or there are other resistances torotational motion with this 620 range.In some instances,therotational displacement could occur in both the inferior andsuperior interfaces.5.Apparatus and Materials5.1 Component Configurations:1This practice is under the jurisdiction ofASTM Committee F04 on Medical andSurgical Materials and Devices and is the direct responsibility of SubcommitteeF04.22 on Arthroplasty.Current edition approved Jan.15,2015.Published February 2015.Originallyapproved in 2008.Last previous edition approved in 2008 as F2722-08.DOI:10.1520/F2722-15.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.1.1 A test construct of the femoral component,mobilebearing component,and tibial tray should be used to provideappropriate interface geometries.5.1.2 The knee joint tibial and femoral components shouldbe assembled and oriented in a manner similar to that in whichthey would function in vivo as depicted in Fig.1.The femoralcomponent is mounted at the maximum flexion angle claimedfor the device by the manufacturer.5.1.3 The tibial component is mounted at zero slope.Thismeans that the flat portion of the superior tibial surface will beperpendicular to the force axis.5.2 Mechanical Testing S