1、Designation: F2025 06 (Reapproved 2018)Standard Practice forGravimetric Measurement of Polymeric Components forWear Assessment1This standard is issued under the fixed designation F2025; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, 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 describes a laboratory method using aweight-loss (that is, mass-loss; see X1.4) technique
3、 for evalu-ating the wear properties of polymeric materials or deviceswhich are being considered for use as bearing surfaces ofhuman joint replacement prostheses. The test specimens areevaluated in a device intended to simulate the tribologicalconditions encountered in the human joint; for example,
4、use ofa fluid such as bovine serum, or equivalent pseudosynovialfluid shown to simulate similar wear mechanisms and debrisgeneration found in vivo.1.2 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision o
5、n Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by D
6、isplacementD1505 Test Method for Density of Plastics by the Density-Gradient TechniqueF732 Test Method for Wear Testing of Polymeric MaterialsUsed in Total Joint ProsthesesF1714 Guide for Gravimetric WearAssessment of ProstheticHip Designs in Simulator Devices2.2 Other Standards:3ISO 142422 Implants
7、 for SurgeryWear ofTotal Hip-JointProsthesesPart 2: Methods of MeasurementISO 142432 Implants for SurgeryWear of Total Knee-Joint ProsthesesPart 2: Methods of Measurement3. Significance and Use3.1 This practice uses a weight-loss method of wear deter-mination for the polymeric components or material
8、s used inhuman joint prostheses, using serum or demonstrated equiva-lent fluid for lubrication, and running under a load profilerepresentative of the appropriate human joint application(1,2).4The basis for this weight-loss method for wear mea-surement was originally developed (3) for pin-on-disk wea
9、rstudies (Practice F732) and has been extended to total hipreplacements (4, 5, ISO 142422, and Guide F1714), and tofemoro-tibial knee prostheses (6 and ISO 142432), and tofemoro-patellar knee prostheses (6,7).3.2 While wear results in a change in the physical dimen-sions of the specimen, it is disti
10、nct from dimensional changesdue to creep or plastic deformation, in that wear results in theremoval of material in the form of polymeric debris particles,causing a loss in weight of the specimen.3.3 This practice for measuring wear of the polymericcomponent is suitable for various simulator devices.
11、 Thesetechniques can be used with metal, ceramic, carbon, polymeric,and composite counter faces bearing against a polymericmaterial (for example, polyethylene, polyacetal, and so forth).Thus, this weight-loss method has universal application forwear studies of human joint replacements which featurep
12、olymeric bearings. This weight-loss method has not beenvalidated for non-polymeric material bearing systems, such asmetal-metal, carbon-carbon, or ceramic-ceramic. Progressivewear of such rigid bearing combinations has generally beenmonitored using linear, variable-displacement transducers, orby oth
13、er profilometric techniques.4. Components and Materials4.1 Hip Prosthesis ComponentsThe hip joint prosthesiscomprises a ball-and-socket configuration in which materialssuch as polymers, composites, metal alloys, ceramics, andcarbon have been used in various combinations and designs.1This practice is
14、 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 April 1, 2018. Published May 2018. Originallyapproved in 2000. Last previous edition approved in 2012 as F2025 06
15、(2012).DOI: 10.1520/F2025-06R18.2For 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 Nati
16、onal Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.4The boldface numbers in parentheses refer to the list of references at the end ofthis standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis internat
17、ional standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Commit
18、tee.14.1.1 Component ConfigurationsThe diameter of theprosthetic ball may vary from 22 to 54 mm or larger. Thedesign may include ball-socket, trunnion, bipolar, or otherconfigurations. If applicable, the normal metal backing for thepolymeric component shall be used provided disassembly andreassembly
19、 of these components for the measurement does nothave an unrepresentative effect on the weight measurements orwear behavior. Otherwise, a modified backing may be used,again provided this has no unrepresentative effect on theweight measurements or wear behavior (see X1.5).4.2 Knee Prosthesis Componen
20、tsThe knee joint comprisesfemoral, tibial, and patellar configurations in which materialssuch as metal alloys, ceramics, polymers, and carbon materialshave been used in various combinations in different designs.4.2.1 Component ConfigurationsThe polymeric compo-nents may be backed by either metal, ce
21、ramic, or compositereinforcements. If applicable, the normal metal backing shallbe used provided disassembly and reassembly of these com-ponents for the measurement does not have an unrepresentativeeffect on the weight measurements or wear behavior.Otherwise, a modified backing may be used, again pr
22、ovidedthis has no unrepresentative effect on the weight measurementsor wear behavior (see X1.5).4.3 Other prosthesis components and test coupons may beused to represent other human joint replacement applications.5. Specimen Preparation5.1 Polymers and CompositesMaterial Condition:5.1.1 A fabrication
23、 history shall be obtained for each poly-meric or composite component, including information such asgrade, batch number and processing variables, method offorming (extruding, molding, and so forth), temperature, pres-sure and forming time used, and any post-forming treatments,including the steriliza
24、tion method and parameters.5.1.2 Pretest characterization may include measurement ofbulk material properties such as molecular-weight range anddistribution, percent crystallinity, or other. Density is a particu-larly important property because of the conversion of weightmeasurements to volumetric we
25、ar (see 7.4). Density measure-ments shall be obtained in accordance with Test Methods D792or Test Method D1505. If it can be justified that previousdensity measurements are representative of the material used inthe current wear test, reference to these previous measurementsand suitable justification
26、 shall be provided (see also X1.6). Thesurface finish of specimens may be characterized byprofilometry, photomicrography, and replication by variousplastics or other techniques.5.1.3 SterilizationThe components shall be sterilized in amanner typical of that in clinical use for such devices, as thism
27、ay affect the wear properties of the materials. Sterilization ofall test and control components within a specific test groupshould be done simultaneously (in a single container) whenpossible to minimize variation among the specimens. The weartesting procedure makes no attempt to maintain the sterili
28、ty ofspecimens during the wear test.5.2 Polymer Specimen Cleaning ProcedurePrior toweighing and wear testing, careful cleaning of the polymerspecimens is important to remove any contaminants that wouldnot normally be present on the actual prosthesis. During thewear test, the components must be re-cl
29、eaned and dried beforeeach weighing to remove any extraneous material that mightaffect the accuracy of the weighing. The procedure for cleaningand drying of polymeric components is given in Annex A1.With some combinations of materials, wear may result in thetransfer of particulate debris which may t
30、hen become re-imbedded or otherwise attached to polymeric, metal, or com-posite surfaces. Such an occurrence will render the weight-lossassessment of wear less reliable.5.3 Polymer Specimen Weighing ProcedureThe polymericcomponents shall be weighed on an analytical balance havinga sensitivity on the
31、 order of 10 g. This degree of sensitivity isnecessary to detect the slight loss in weight of polymers suchas ultra-high-molecular-weight polyethylene (UHMWPE),which may wear 1 mg or less per million cycles. Specimensshall always be weighed in the clean, dry condition (AnnexA1). The components shall
32、 be kept in a dust-free container andhandled with clean tools to prevent contamination which mightaffect the weight measurement. Each wear and control compo-nent shall be weighed three times in rotation to detect randomerrors in the weighing process.5.4 Pre-Soaking of Test Specimens:5.4.1 Polymeric
33、and composite components made frommaterials which absorb fluid initially, but saturate within a fewweeks, should be presoaked in the test lubricant to reduce theerror due to fluid sorption during the wear run. If the fluidsorption behavior of a particular material is unknown, theinvestigator shall c
34、onduct a preliminary study to determinewhether or not the material is exempt from presoaking.5.4.2 Preliminary StudyA minimum of three soak speci-mens (these can be test coupons or actual devices) per materialshall be cleaned and dried in accordance with the procedure inAnnex A1, and then weighed by
35、 precisely controlled andrepeatable methods (Annex A1). The specimens shall then beplaced in a container of test lubricant and removed, cleaned,dried, and weighed (in accordance with Annex A1) once ortwice a week. The weight change shall be calculated inaccordance with Annex A1. The procedure shall
36、be repeateduntil the specimens have soaked for five weeks. Specimenweight change shall be averaged at each interval and plottedversus time. Data points shall be fit using a second or thirdorder polynomial or hyperbolic function, connecting throughzero. The fit of this curve should have an R2value of
37、 0.8 orgreater. If the slope of this curve at five weeks is ten or moretimes less than the slope of the curve at zero (see X1.7), thenthis material shall be subjected to presoaking before weartesting (if gravimetric wear measurement is to be used).Otherwise, it is exempt.NOTE 1Even if presoaking is
38、not required, one to three soak controlcomponents are still necessary per material condition to account for fluidsorption by the wear components during the wear test.5.4.3 Pre-soaking Procedure (if Required)After fabrica-tion and characterization, the wear components and one tothree soak-control com
39、ponents of each test material shall becleaned in accordance with the procedure in Annex A1. TheF2025 06 (2018)2wear components and soak control(s) shall then be placed in acontainer of test lubricant for a minimum of five weeks (35days).6. Measurement Procedure6.1 After fabrication, characterization
40、, and the completionof the presoak period (if required), the wear components andsoak control(s) should be cleaned, dried, and weighed byprecisely controlled and repeatable methods (Annex A1).These weights shall be recorded as the initial weights of thespecimens for purposes of calculating the progre
41、ssive weightloss during the wear test. The soak control specimen(s) shall beplaced in holders in a soak chamber of test lubricant, such thatthe total surface area exposed to the lubricant is equal to that ofthe wear components when mounted in the test chamber. Thesoak chamber temperature shall be ma
42、intained at the sametemperature as the bulk lubricant in the wear test, or specifiedif different. It is recommended that the soak chamber beattached to the test machine or otherwise agitated in the samemanner as the actual wear chambers. In addition, it may beadvantageous to apply a cyclic load to t
43、he soak controlspecimen(s) (without tangential motion) comparable to thatapplied to the wear specimens, since this can also affect the rateof fluid sorption.6.2 The wear and soak component(s) shall be removed atspecified intervals, washed, rinsed, and dried concurrently, inaccordance with the proced
44、ure in Annex A1. It is importantthat both the wear and soak component(s) be treated identicallyto ensure that they have the same exposure to the wash, rinse,and drying fluids. This will provide the most accurate correc-tion for fluid sorption by the wear specimens.6.3 After rinsing and drying, the w
45、ear components and soakcontrols shall be weighed on an analytical balance in accor-dance with 5.3.6.4 The wear chambers and component surfaces shall bethoroughly rinsed with distilled or deionized water.6.5 The bearing surfaces of the components shall beinspected, and the characteristics of the wear
46、 process noted.Visual, microscopic, profilometric, replication, or other inspec-tion techniques can be used. However, care must be taken thatthe surfaces do not become contaminated or damaged by anysubstance or technique which might affect the subsequent wearproperties. If contamination occurs, the
47、specimens shall bethoroughly re-cleaned prior to restarting the wear test.6.6 The wear components and soak control(s) shall bereplaced in fresh lubricant and wear cycling continued.7. Determination of Wear Rates7.1 Test LengthThe accuracy of the test method dependson the relative magnitudes of wear
48、and fluid sorption. This isespecially true when the fluctuations in the weight due tovariation in the amount of surface drying are large in compari-son to the incremental weight loss due to wear. For high-wearlow-sorption materials, the wear rate may be clearly estab-lished in as few as 50 000 wear
49、cycles. With comparativelylow-wearing materials, such as UHMWPE, several millioncycles or more may be required to clearly establish thelong-term wear properties.7.2 Number of Measurements per TestWhen specimenscan be removed for intermediate weight measurement, at leastthree measurements per test series shall be made.7.3 Correcting for Fluid SorptionThe average gain (orloss) of the soak control component(s) shall be added to (orsubtracted from) the measured weight loss of each wearcomponent (Annex A2.6). This procedure corrects both forsystematic sorption as w
