ASTM_F_1440_-_92_2002.pdf

Designation:F 1440 92(Reapproved 2002)Standard Practice forCyclic Fatigue Testing of Metallic Stemmed Hip ArthroplastyFemoral Components Without Torsion1This standard is issued under the fixed designation F 1440;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(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice describes a method for the fatigue testingof metallic stemmed femoral components used in hip arthro-plasty.The described method is intended to be used to evaluatethe comparison of various designs and materials used forstemmed femoral components used in the arthroplasty.Thispractice covers procedures for the performance of fatigue testsusing(as a forcing function)a periodic constant amplitudeforce.1.2 This practice applies primarily to one-piece prosthesesand modular components,with head in place such that pros-theses should not have an anterior/posterior bow,and shouldhave a nearly straight section on the distal 50 mm of the stem.This practice may require modifications to accommodate otherfemoral stem designs.1.3 The values stated in SI units are to be regarded as thestandard.1.4 For additional information see Refs.(1-5).2.Referenced Documents2.1 ASTM Standards:E 4 Practices for Force Verification of Testing Machines2E 466 Practice for Conducting Force Controlled ConstantAmplitude Axial Fatigue Tests of Metallic Materials2E 467 Practice for Verification of Constant Amplitude Dy-namic Forces in an Axial Fatigue Testing System2E 468 Practice for Presentation of Constant Amplitude Fa-tigue Test Results for Metallic Materials23.Terminology3.1 Definitions and Symbols(see Fig.1(a)and 1(b):3.1.1 cantilever planea plane perpendicular to the line ofload application at the level on the stem where the stembecomes unsupported.3.1.2 distal stem axisthe centerline in the anterior/posterior projection of the most distal 50 mm of the stem.3.1.3 estimated maximum bending momentthe maximumload times the unloaded moment arm.3.1.4 geometric centroid(cantilever plane)the point in across-sectional area of the cantilever plane whose coordinatesare the mean values of the coordinates of all the points in thearea.3.1.5 line of load applicationthe loading axis of the testmachine.3.1.6 Reference Line L1,distal stem axisthe medial-lateral(M-L)centerline of the most distal 50 mm of stem in theA-P projection.3.1.7Reference Line L2:3.1.7.1 collared device the plane of the distal side of thecollar in the A-P projection.3.1.7.2 collarless devicethe resection plane recommendedfor the device in the A-P projection.3.1.8 Reference Point P1the spherical center of the pros-thesis head.3.1.9 Reference Point P3:1This 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 Sept.15,1992.Published November 1992.2Annual Book of ASTM Standards,Vol 03.01.FIG.1 Collared Device1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.3.1.9.1 collared device the intersection of the principalaxis of the collar(L2)with the medial surface of the stem in theA-P projection.3.1.9.2 collarless devicethe intersection of the resectionplane(L2)with the medial surface of the stem in the A-Pprojection.3.1.10 Reference Point P4the distal tip of the stem.3.1.11 Reference Point P63 the intersection of the canti-lever plane with the medial surface of the stem in the A-Pprojection.3.1.12 R valuethe R value is the ratio of the minimumforce to the maximum force.R 5minimum forcemaximum force3.1.13 Stem Reference Angle Xthe angle between the stemreference line and the line of load application.3.1.14 stem reference linea line passing through Refer-ence Point P6 and the center of the prosthesis head(P1).3.1.15 supported stem lengththe vertical distance be-tween the distal tip of the stem(P4)and the cantilever plane.3.1.16 unloaded moment armthe perpendicular distancebetween the line of load application and the geometric centroidof the stem cross section at the cantilever plane.3.1.17 unsupported stem lengththe vertical distance be-tween Point P3 and the cantilever plane.3.2 See Figs.1 and 2.4.Significance and Use4.1 This practice can be used to describe the effects ofmaterials,manufacturing,and design variables on the fatigueresistance of metallic stemmed femoral components subjectedto cyclic loading for relatively large numbers of cycles.Therecommended test assumes a“worst case situation whereproximal support for the stem has been lost.It is alsorecognized that for some materials the environment may havean effect on the response to cyclic loading.The test environ-ment used and the rationale for the choice of that environmentshould be described in the report.4.2 It is r