1、Designation: F1800 07F1800 12Standard Test Method Practice forCyclic Fatigue Testing of Metal Tibial Tray Components ofTotal Knee Joint Replacements1This standard is issued under the fixed designation F1800; the number immediately following the designation indicates the year oforiginal adoption or,
2、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 test method practice covers a procedure for the fatigue testing of metallic
3、tibial trays used in knee joint replacements.This test method practice covers the procedures for the performance of fatigue tests on metallic tibial components using a cyclic,constant-amplitude force. It applies to tibial trays which cover both the medial and lateral plateaus of the tibia. This test
4、 methodpractice may require modifications to accommodate other tibial tray designs.1.2 This test method practice is intended to provide useful, consistent, and reproducible information about the fatigueperformance of metallic tibial trays with one unsupported condyle.1.3 The values stated in SI unit
5、s are to be regarded as the standard. The inch-pound units given in parentheses are forinformation only.No other units of measurement are included in this standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof th
6、e user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E4 Practices for Force Verification of Testing MachinesE467 Practice for Verification of Constant Amplitude Dy
7、namic Forces in an Axial Fatigue Testing SystemE468 Practice for Presentation of Constant Amplitude Fatigue Test Results for Metallic MaterialsE1150 Definitions of Terms Relating to Fatigue (Withdrawn 1996)33. Terminology3.1 Definitions:3.1.1 R valueThe R value is the ratio of the minimum load to th
8、e maximum load.R 5 minimum loadmaximum load (1)3.2 Definitions of Terms Specific to This Standard:3.2.1 anteroposterior centerlinea line that passes through the center of the tibial tray, parallel to the sagittal plane andperpendicular to the line of load application. For asymmetric tibial tray desi
9、gns, the appropriate center of the tibial tray shall bedetermined by the investigator and the rationale reported.3.2.2 fixture centerlinea line that passes through the center of the fixture, parallel to the anteroposterior centerline. This linerepresents the separation between the supported and unsu
10、pported portions of the test fixture.3.2.3 mediolateral centerlinea line that passes through the center of the tibial tray, parallel to the coronal, or frontal, planeand perpendicular to the line of load application. For asymmetric tibial tray designs, the appropriate center of the tibial tray shall
11、be determined by the investigator and the rationale reported.1 This test method practice is under the jurisdiction of ASTM Committee F04 on Medical and Surgical Materials and Devices and is the direct responsibility ofSubcommittee F04.22 on Arthroplasty.Current edition approved Sept. 15, 2007Dec. 15
12、, 2012. Published October 2007January 2013. Originally approved in 1997. Last previous edition approved in 20042007as F1800 04.F1800 07. DOI: 10.1520/F1800-07.10.1520/F1800-12.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For
13、 Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 The last approved version of this historical standard is referenced on www.astm.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard
14、an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is
15、to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.4 moment arm, dapthe perpendicular distance between the mediolateral centerline of the tibia component and the line ofload application.3.2.5 mo
16、ment arm, dmlthe perpendicular distance between the anteroposterior centerline of the tibia component and the lineof load application.4. Significance and Use4.1 This test method practice can be used to describe the effects of materials, manufacturing, and design variables on the fatigueperformance o
17、f metallic tibial trays subject to cyclic loading for relatively large numbers of cycles.4.2 The loading of tibial tray designs in vivo will, in general, differ from the loading defined in this test method. practice. Theresults obtained here cannot be used to directly predict in vivo performance. Ho
18、wever, this test method practice is designed to allowfor comparisons between the fatigue performance of different metallic tibial tray designs, when tested under similar conditions.4.3 In order for fatigue data on tibial trays to be comparable, reproducible, and capable of being correlated among lab
19、oratories,it is essential that uniform procedures be established.5. Specimen Selection5.1 The test component selected shall have the same geometry as the final product, and shall be in finished condition.6. Apparatus6.1 The tibial tray shall be mounted as a cantilever beam (see Fig. 1 and Fig. 2). C
20、are shall be taken to ensure that the fixationof the tibial tray does not produce abnormal stress concentrations that could change the failure mode of the part. One possible setupinvolving fixation of the inferior surface or clamping of the superior surface is shown in Fig. 1 and Fig. 2. If necessar
21、y, bone cementor other high strength epoxy may be used on the supported aspect of the tibial tray to prevent loosening during the test.6.2 The tibial tray shall be positioned such that the anteroposterior centerline and the fixture centerline are aligned with anaccuracy of 61 mm in the x direction a
22、nd 62 in the xy plane (see Fig. 1 and Fig. 2).6.3 When the tibial tray design includes a central keel or other prominence, the proper method for support of the keel must bedetermined. Depending on the tibial tray design, it may be necessary to evaluate the design with or without support of the keel(
23、see Fig. 2). The method of supporting (or not supporting) any such feature shall be reported.FIG. 1 Schematic of Test Setup Without a Central KeelF1800 1226.4 A spacer of plastic possessing sufficient stiffness and creep resistance (for example, ultra high molecular weightpolyethylene, acetal co-pol
24、ymer) shall be placed between the tibial tray and the load applicator (see Fig. 3). The spacer shallcontain a spherical indentation (or recess) for the spherical indenter. This recess shall be greater to or equal than the diameter ofthe spherical indenter and is included to minimize the chance of sp
25、acer fracture under load. The spacer shall have a minimumthickness of 6 mm (0.25 in.), mm, measured at the dome of the sphere. It is recommended that the diameter of the spacer is 13mm (0.5 in.).mm.NOTE 1Actual dimensions of the spacer may vary as smaller tibial tray designs may require a smaller di
26、ameter disk.6.4.1 The spacer shall be placed on the unsupported tibial condyle. The purpose of the spacer is to distribute load to the tibialtray condyle and to eliminate possible fretting fatigue initiated by contact between the metal indenter and the tibial tray.FIG. 2 Schematic or Test Setup With
27、 a Central KeelFIG. 3 Recommended Spacer DrawingF1800 1236.5 The fixturing shall be constructed so that the load shall be applied perpendicular to the undeflected superior surface of thetibial tray.6.6 Use one of the following two methods for determining the position of the loading point.6.6.1 For t
28、ibial articulating surface designs that have a concave surface, the loading point shall be the intersection with the trayof a line perpendicular to the tray which intersects the deepest part of the concave recess of the articulating surface of the tibialcomponent.6.6.2 For other tibial designs, the
29、femoral component, the tibial articulating surface, and the tibial tray shall be assembled at 0flexion and the position of the center of pressure determined. The loading point shall be the intersection of the line perpendicularto the tray which intersects the center of the pressure contact area.NOTE
30、 2Optionally, define the worst-case scenario considering the potential translation in the transverse plane and/or the potential axial rotation (1)4of the femoral component relative to the tibial baseplate, and apply 6.6.1 or 6.6.2. The rationale for the choice of femoral component placement relative
31、to the tibial baseplate should be reported.NOTE 3If the geometry of the tibial baseplate superior surface prevents using and dap and dml for the load application (for example, the presence ofprotrusion at the location of the theoretical load application), the rationale for the choice of the appropri
32、ate load location should be reported (X1.6 is anexample of the variation that could occur due to tibial baseplate misalignment).6.6.3 The dap and the dml shall be determined from either of the above techniques and will be used for all testing of that designin that size.6.7 The load shall be applied
33、by means of a spherical indenter, a diameter of 32 mm (1.25 in.) is recommended.7. Equipment Characteristics7.1 Perform the tests on a fatigue test machine with adequate load capacity.7.2 Analyze the action of the machine to ensure that the desired form and periodic force amplitude is maintained for
34、 the durationof the test (see Practice E467 or use a validated strain gaged part).7.3 The test machine shall have a load monitoring system such as the transducer mounted in line with the specimen. Monitorthe test loads continuously in the early stages of the test and periodically thereafter to ensur
35、e the desired load cycle is maintained.Maintain the varying load as determined by suitable dynamic verification at all times to within 62 % of the largest compressiveforce being used.8. Procedure8.1 Determine the size of the tibial tray component used by the investigator. Dimensions shall be reporte
36、d.8.2 Position the test specimen such that the load axis is perpendicular to the undeflected superior surface of the tray since thetray surface will not remain perpendicular to the load axis during loading.8.3 Mount one side of a symmetric tibial component on the fixture (see Fig. 1 and Fig. 2). Use
37、 the centerline of the tray todistinguish between supported and non supported sides. If asymmetrical, fix the tibial component such that a worst case conditionis tested. Report the criteria used to distinguish between supported and not supported sides.8.4 Apply the load by means of a spherical inden
38、ter.8.5 Test frequencyRun all tests at a frequency of 30 Hz or less. Take care to ensure that the test machine can maintain theapplied load at the chosen frequency and that resonant conditions are not reached.8.6 R valueRun all tests with an R value of 10.0.NOTE 4In strict terms, since the force app
39、lied to the tray is compressive, the maximum force is the smallest negative amplitude. Consequently, theR value is ten when the negative signs cancel each other. In terms of applied bending moment at the cantilever plane, the R value would be 0.1. SeeTerminology E1150 for the definition of the R val
40、ue.8.7 Measure the vertical deflection of the tibial tray using a dial gage, displacement transducer, and so forth. Record the pointat which the deflection is measured (that is, under the applied load, at the point of maximum deflection).8.8 Report the test environment used.9. Test Termination9.1 Co
41、ntinue the test until the tibial tray fails or until a predetermined number of cycles has been applied to the implant. Thesuggested number of cycles is ten million. Failure may be defined as: a fracture of the tibial tray; formation of a crack detectableby eye, fluorescent dye penetrant, or other no
42、n-destructive means; or exceeding a predetermined deflection limit.10. Report10.1 Report the fatigue test specimens, procedures, and results in accordance with Practice E468.4 The boldface numbers given in parentheses refer to a list of references at the end of the test.F1800 12410.2 In addition, re
43、port the following parameters: tibial tray material, spacer diameter and thickness, indenter diameter, overallanteroposterior and mediolateral dimensions of the tray, location of anteroposterior and mediolateral centerlines (for asymmetrictibial trays), tibial condyle loaded (for asymmetric tibial t
44、rays), dml,dap, fixation method, largest compressive load, R value, cyclesto failure, mode and location of failures, test environment, and test frequency. The method for determining the loading locationon the tibial tray (that is, dml, and dap) shall be documented.11. Precision and Bias11.1 TheAprec
45、ision and bias of this test method needs to be established. Test results that can be used to establish precision andbias are solicited.statement does not exist for this practice.12. Keywords12.1 arthroplasty; orthopaedic medical devices; tibial components; total knee arthroplastyAPPENDIX(Nonmandator
46、y Information)X1. RATIONALEX1.1 Fractures of tibial trays in TKR have occurred in clinical applications (2-6). The tray design, quality of bone, and otherfeatures contribute to implant fracture. One recognizable mode of clinical failure occurs when the lateral portion of the tray isfirmly anchored w
47、hile bone support of the medial condyle is absent. As the body loads are applied through the tray of theprosthesis, significant stresses can result at the area where the tray is still firmly supported. Because it is believed that this lackof support is the primary reason behind fracture of the tibia
48、l trays, this test method practice was chosen as a simplified model touse in fatigue testing of actual implants.X1.2 It is recognized that for some materials the environment may have an effect on the response to cyclic loading. The testenvironment used and the rationale for that choice shall be desc
49、ribed in the test report.X1.3 It is also recognized that actual in vivo loading conditions are not constant amplitude. However, there is insufficientinformation available to create standard load spectrums for metallic tibial components. Accordingly, a simple periodic constantamplitude force is recommended.X1.4 Worst case loading of the tibial tray may vary depending on material, design, and clinical indications. The researcher shallevaluate the possible clinical and design related failure modes and attempt to determine a worst case situation. As stated above,l
