1、Designation: F 2345 03 (Reapproved 2008)Standard Test Methods forDetermination of Static and Cyclic Fatigue Strength ofCeramic Modular Femoral Heads1This standard is issued under the fixed designation F 2345; 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 These test methods cover the evaluation of the static andcyclic fatigue strength
3、 of ceramic modular femoral heads,mounted on a cone as used on the femoral stem of the total hiparthroplasty.1.2 These test methods were primarily developed for evalu-ation of ceramic (Specifications F 603 and F 1873) headdesigns on metal cones but may have application to othermaterials.1.3 The valu
4、es stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 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 saf
5、ety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E4 Practices for Force Verification of Testing MachinesF 603 Specification for High-Purity Dense Aluminum Ox-ide for Medical ApplicationF 1873 Specification for
6、 High-Purity Dense Yttria Tetrago-nal Zirconium Oxide Polycrystal (Y-TZP) for SurgicalImplant Applications3F 1875 Practice for Fretting Corrosion Testing of ModularImplant Interfaces: Hip Femoral Head-Bore and ConeTaper Interface2.2 Other Documents:DIN 4768 Determination of Surface Roughness Ra,Rz,
7、andRmaxwith Electric Stylus Instruments; Basic Data4FDA Guidance Document for the Preparation of PremarketNotifications for Ceramic Ball Hip Systems (draft Jan. 10,1995)53. Terminology3.1 Definitions:3.1.1 circularitydeviations of taper cross section from aperfect circle.3.1.2 conethe proximal end o
8、f the femoral componentfabricated as a truncated right cone and used to engage with amating conical bore of the modular femoral head.3.1.3 cone angleincluded angle of cone (Fig. 1).3.1.4 femoral neck-axiscenterline or axis of symmetry ofthe femoral cone.3.1.5 head sizenominal spherical diameter of t
9、he head(generally standardized, but not limited to 22, 26, 28, 32, and36 mm for total hips.)3.1.6 installation loadthe force, applied at 0 from femo-ral neck axis, used to settle the head on the cone prior totesting.3.1.7 load axisline of action of the compressive forceapplied to the head.3.1.8 load
10、 axis anglethe measured angle “L” between theline of action of the applied force and femoral neck axis (seeFig. 5).3.1.9 load magnitudethe peak (absolute value) compres-sive force of the applied constant amplitude cyclic force.3.1.10 load raterate of applied compressive force.3.1.11 stroke ratethe r
11、ate of the stroke displacement ofthe force applicator.3.1.12 surface finishmeasured roughness of surface oftaper cone or head bore as determined by DIN 4768.3.1.13 test frequencythe rate of cyclic repetition of fatigueloading in cycles per second.1This test method is under the jurisdiction ofASTM Co
12、mmittee F04 on Medicaland Surgical Materials and Devices and is the direct responsibility of SubcommitteeF04.22 on Arthroplasty.Current edition approved Dec. 15, 2008. Published December 2008. Originallyapproved in 2003. Last previous edition approved in 2003 as F 2345 03.2For referenced ASTM standa
13、rds, 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.3Withdrawn. The last approved version of this historical standard is referencedon www.as
14、tm.org.4Available from Beuth Verlag GmbH (DINDIN Deutsches Institut furNormung e.V.), Burggrafenstrasse 6, 10787, Berlin, Germany.5Available from Food and Drug Administration (FDA), 5600 Fishers Ln.,Rockville, MD 20857.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohoc
15、ken, PA 19428-2959, United States.3.1.14 THRtotal hip replacement.4. Significance and Use4.1 These test methods can be used to determine the effectsof head and cone materials, design variables, manufacturing,and other conditions on the static and cyclic load-carryingability of modular femoral heads
16、mounted on the cones offemoral stem prostheses.4.2 These test methods may use actual femoral prostheses orneck-cone models of simplified geometry with the samegeometrical and material characteristics as in the implants. Ineither case, the matching metallic cone region of the testspecimen selected sh
17、all be of the same material, tolerances, andfinishing as the final femoral stem prosthesis.4.3 The static test data may yield valuable informationabout the relative strengths and merits of different head andcone designs for particular applications. Due to the high forcesanticipated for this type of
18、destructive test (40 kN), theboundary conditions and load levels far exceed possible in vivoloading parameters and therefore may not necessarily beapplicable as a quantitative indicator of expected in vivo deviceperformance.4.4 In the fatigue test methods, it is recognized that actualloading in vivo
19、 is quite varied, and that no one set ofexperimental conditions can encompass all possible variations.FIG. 1 Geometrical Design Criteria for Modular BallFIG. 2 Geometrical Design Criteria for Mating Conical FitFIG. 3 Loading in a Metal ConeFIG. 4 Loading Through a Copper RingF 2345 03 (2008)2Thus, t
20、he test methods included here represent a simplifiedmodel for the purposes of comparisons between designs andmaterials. These test methods are intended to be performed inair.4.5 The test data may yield valuable information about therelative strengths of different head and cone designs.5. Apparatus5.
21、1 The loading fixtures should be capable of sustainingforces up to the anticipated fracture level. The static loadingfixtures may require load capacity up to 200 kN in somecircumstances. The fatigue tests should use fixtures withfatigue load capacity up to 50 kN.5.2 The fixtures shall be constructed
22、 so that the line of forceapplication passes through the center of the femoral head.5.3 Due to the high forces anticipated in this type of cyclic,destructive test, appropriate shielding of the modular ball testsite is recommended.6. Equipment Characteristics6.1 Generally, the static tests should be
23、performed on eithermechanical (power screws) or hydraulic (servo-hydraulic) loadframes with adequate load capacity (up to 200 kN). The fatiguetests should generally be performed on hydraulic (servo-hydraulic) load frames with adequate load capacity (up to 50kN). The test equipment should meet the re
24、quirements outlinedin Practices E4.6.2 The varying force, as determined by suitable dynamicverification, should be maintained at all times to within 62%of the largest compressive force being used for the duration ofthe test.7. Procedure7.1 Sample Assembly:7.1.1 Following normal laboratory cleaning p
25、rocedures toremove any debris or other surface contaminants, the head andcone are assembled on a suitable test machine. A suggestedprocedure for cleaning and drying of the specimens is given inAppendix X1. Any cleaning procedures used should be con-sistent with typical manufacturing practices.7.1.2
26、The stem taper cones are mounted at 0 load angle (L= 0). An assembly force of 2 kN is used to mount the femoralball and achieve a standard head/cone reference position priorto all tests.7.1.3 Pre-assembly of the head on the taper should beconducted under stroke or load control at a rate that willcon
27、sistently produce the required 2 kN assembly load with lessthan 50 N of overshoot. One of the following loading condi-tions for assembly is suggested:7.1.3.1 A loading rate of 500 N/s 6 100.7.1.3.2 A stroke rate of 0.04 mm/s.7.2 General Test Requirements:7.2.1 The tests are performed at room tempera
28、ture in air.7.2.2 New test cones and femoral heads shall be used foreach test. Note that it is imperative that components thatsurvive the test should not be used for clinical purposes aftertesting.7.2.3 The load axis angle “L” shall be maintained within61 for all test samples.NOTE 1Precautions shoul
29、d be taken to protect the test operator frominjury by fragments should the specimen shatter when under load or whendisassembling or when storing the specimen after removal of the forcefrom unfractured specimens.7.3 Static On Axis Test Method:7.3.1 The load axis angle “L” is 0.7.3.2 Number of Test Sp
30、ecimensAminimum of five speci-mens is recommended for a test group.7.3.3 The femoral head may be loaded through a hardened(minimum 150 HB) metal 100 6 1 cone with a minimumsurface diameter of 0.75 times the head diameter (Fig. 3)oralternatively, the contact surface may be protected by means ofa copp
31、er ring (Fig. 4). A suggested minimum thickness for thecopper ring is 1.25 mm and it should extend about 2.25 mm oneither side of the contact diameter. The diameter of contact forthe applied force should be approximately 0.643 times the headsize.7.3.4 The conical metal loading fixture may be damaged
32、 ifthe test fractures the sample. It shall be examined after eachtest fracture and be discarded if damaged. If a copper ring isused for the contact, a new ring shall be used for each test.7.3.5 Use of one of the following loading conditions arerecommended:7.3.5.1 Position control with a stroke rate
33、of 0.04 mm/s(0.0015 in./s) or,7.3.5.2 Load control with a loading rate of 1 kN/s (224.8lb/s) or less.7.4 On Axis Fatigue Test Method:7.4.1 The maximum test frequency shall not exceed 30 Hz.7.4.2 The load axis angle “L” is 0.7.4.3 The femoral head may be loaded through a hardenedmetal 100 6 1 cone (F
34、ig. 3) or alternatively, the contact ringmay be protected by means of a copper ring (Fig. 4). Asuggested minimum thickness for the copper ring is 1.25 mmand it should extend about 2.25 mm on either side of thecontact diameter. The diameter of contact for the applied forceFIG. 5 Pictorial Example of
35、the Load Angle “L”F 2345 03 (2008)3should be the head diameter multiplied by the cosine of 50 or0.643 times the head diameter.7.4.4 The conical metal loading fixture may be damaged ifthe test fractures the sample. It should be examined after eachtest fracture and be discarded if damaged. If a copper
36、 ring isused for the contact surface, a new ring should be used for eachtest.7.4.5 The fatigue force shall have a sinusoidal waveformapplied from the force magnitude to a minimum that is 10 % ofthe load magnitude.7.4.6 The cyclic forces should be applied until 10 millioncycles without failure of the
37、 components or until fracture hasoccurred.7.5 Off Axis Fatigue Test Method:7.5.1 The maximum test frequency shall not exceed 30 Hz.7.5.2 The load axis angle “L” is 30.7.5.3 A polymeric spherical concave component with thesame segment diameter as suggested in 7.4.3 should be used(Fig. 5). The segment
38、 diameter should not change during thetest.7.5.4 The fatigue force shall have a sinusoidal waveformapplied from the force magnitude to a minimum that is 10 % ofthe load magnitude.8. Report8.1 The minimum required report shall identify the manu-facturer(s), head size, femoral head material, the defin
39、ition offailure used in the test, the cone material, and the description ofthe cone and taper geometries.8.2 The report shall also describe the test equipment and alltest parameters.8.2.1 For the static test, the control mode, the loading rate,and a description of the loading contact.8.2.2 For the f
40、atigue tests, the test frequency, the peak force,the load axis angle “L,” load amplitude, and a description ofthe loading contact for each sample.8.3 Test Results:8.3.1 For the static test, the maximum failure force for eachsample is required. Reporting of the mean failure force,standard deviation,
41、and range is also recommended.8.3.2 For the fatigue test methods, the number of cyclescompleted by the sample and whether the sample failed. Astatement justifying the number and kinds of samples should beincluded (FDA Guidance Document).8.4 Additional optional information characterizing the boreand
42、cone dimensions and tolerances (Figs. 1 and 2) would bedesirable to better interpret the test results. This informationmay include, but is not limited to the following: cone type,head bore angle, head bore major/minor diameters, boresurface roughness (Ra,Rzper DIN 4768), cone angle, conediameter, co
43、ne surface roughness (Ra,Rzper DIN 4768),length of mating interface between the bore and cone, andmethod of femoral ball sterilization.9. Precision and Bias9.1 PrecisionFor a destructive test, wherein replicatemeasurements cannot be made on a single test sample, dis-agreement between replicate measu
44、rements on differentsamples includes actual part-to-part variability in the propertybeing measured as well as methodological imprecision. It isimpossible to design an experiment that can separate thesefactors. Thus, any statements regarding precision include bothfactors.9.1.1 The precision and bias
45、of these test methods need to beestablished. Test results that can be used to establish precisionand bias are solicited.9.1.2 The following data are offered for guidance.Atotal of32 nominally identical alumina heads (28-mm diameter,1214-mm modular taper), representing four different manufac-turing l
46、ots, were tested for static ultimate compressive strength(UCS) when attached toTi6Al4Vtapers, by a single laboratory.The data are summarized as follows:LotDesig-nationSampleSizeMaximumUCSMinimumUCSMeanUCSStd.DeviationkN kN kN kN (% of mean)1 10 57 49 53.4 2.5 (4.7 %)2 8 62 54 57.2 2.4 (4.2 %)3 10 64
47、 46 56.2 5.7 (10.1 %)4 4 58 54 56.5 1.7 (3.0 %)9.1.3 For these four sets of data, one can estimate theweighted repeatability standard deviation as 6.0 % of meanUCS. Phrased differently, the experience from this one labo-ratory would indicate that any two measurements at the samelaboratory would be e
48、xpected to differ by more than 23.7 % oftheir mean value no more than one time in 20.10. Keywords10.1 bore; ceramic; cone; fatigue; modular head; static;strengthF 2345 03 (2008)4APPENDIXES(Nonmandatory Information)X1. RATIONALEX1.1 Modular or interchangeable femoral heads have beenused in various TH
49、R designs since approximately 1970. Thisconcept provides several features to suit the patient as plannedpre-operatively or selected intra-operatively by the surgeon, orboth, such as component material, neck-lengths, or headdiameters, or combination thereof.X1.2 The alumina ceramic (Specification F 603)-metalfriction lock fit has been used for head diameters 32 mm and 28mm in Europe from 1973 onwards and in Japan from 1977onwards, respectively. Zirconia ceramic (SpecificationF 1873)-metal friction lock fit has been used for head diameters32 mm, 28 mm,
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