1、Designation: F732 00 (Reapproved 2011)F732 17Standard Test Method forWear Testing of Polymeric Materials Used in Total JointProstheses1This standard is issued under the fixed designation F732; the number immediately following the designation indicates the year of originaladoption or, in the case of
2、revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method describes a laboratory method for evaluating the wear properties of combinations of
3、 materials that arebeing considered for use as bearing surfaces of human total joint prostheses.The body of this test method contains general methodswhich apply to all types of prosthesis wear applications while individual annexes describe specific wear test methods and clinicalvalidation criteria t
4、ailored to each distinct wear application (for example, linear reciprocating motion, ball-cup (“hip-type”) wear,delamination wear, etc.). and so forth). It is the intent of this test method to rank materials, within each wear application, forpolymer wear rates under simulated physiological condition
5、s. It must be recognized, however, that contact geometries and wearmotions are simplified using such methods. This test method, therefore, represents only an initial stage in the full wearcharacterization of a candidate material.1.2 All candidate materials should be tested in an appropriate joint si
6、mulator apparatus using prototype prostheses before beingused in clinical trials in patients. The tests described in this test method are used to quickly and reliably screen materialcombinations for wear performance in different orthopaedic wear applications prior to committing them to more expensiv
7、e andtime-consuming joint simulator testing. In addition, these simplified tests can be used to relate material, surface finish, or otherparameters to wear behavior on a more practical basis than is possible in joint simulator tests.1.3 The values stated in either SI units or inch-pound units are to
8、 be regarded separately as standard. The values stated in eachsystem may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from thetwo systems may result in non-conformance with the standard.1.4 This international standard was developed in ac
9、cordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM
10、 Standards:2D883 Terminology Relating to PlasticsF75 Specification for Cobalt-28 Chromium-6 Molybdenum Alloy Castings and Casting Alloy for Surgical Implants (UNSR30075)F86 Practice for Surface Preparation and Marking of Metallic Surgical ImplantsF648 Specification for Ultra-High-Molecular-Weight Po
11、lyethylene Powder and Fabricated Form for Surgical ImplantsF799 Specification for Cobalt-28Chromium-6Molybdenum Alloy Forgings for Surgical Implants (UNS R31537, R31538,R31539)F1537 Specification for Wrought Cobalt-28Chromium-6Molybdenum Alloys for Surgical Implants (UNS R31537, UNSR31538, and UNS R
12、31539)F2025 Practice for Gravimetric Measurement of Polymeric Components for Wear AssessmentG40 Terminology Relating to Wear and Erosion3. Terminology3.1 Definitions of Terms Specific to This Standard:1 This test method is under the jurisdiction of ASTM Committee F04 on Medical and Surgical Material
13、s and Devices and is the direct responsibility of SubcommitteeF04.15 on Material Test Methods.Current edition approved June 1, 2011Sept. 1, 2017. Published July 2011October 2017. Originally approved in 1982. Last previous edition approved in 20062011 asF732 00 (2006).(2011). DOI: 10.1520/F0732-00R11
14、.10.1520/F0732-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and i
15、s intended only to provide the user of an ASTM standard 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
16、 current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.1 wearfor the purpose of this test method, the progressive loss of material from the po
17、lymer specimen as a result of theoscillating motion against the counterface under load. Wear may be generated by several mechanisms including adhesion, two orthree body abrasion, surface fatigue, or other processes.3.1.2 wear ratethe volume of material lost due to wear per unit of sliding distance (
18、or per million wear cycles if complexmotion patterns result in a non-uniform sliding distance across the specimen; see 4.3).4. Significance and Use4.1 This test method is intended to be performed in conjunction with pin-on-flat wear machines or similar machines that aredesigned to evaluate simplifie
19、d specimen geometries.NOTE 1See Haider however, if the sliding distanceis not constant across the polymeric specimen surface due to complex motion patterns, wear may be reported as volume loss ofthe polymeric specimen as a function of wear cycles (in which case a “wear cycle” shall be defined). Volu
20、me loss of the polymerspecimen is determined by dividing the experimental weight loss by the density of the polymer. For ease of interpretation, wearshould be reported as a function of both the number of wear cycles and the sliding distance, when possible.4.4 The reference for the comparative evalua
21、tion of candidate materials shall be the wear rate of ultra-high-molecular-weightpolyethylene (UHMWPE) conforming to Specification F648 bearing against counterfaces of cobalt-chromium-molybdenum alloy(in accordance with Specifications F75, F799, or F1537), having prosthetic-quality surface finish an
22、d lubricated with bovine bloodserum (see 5.2).5. Apparatus and Materials5.1 Orthopaedic Wear Application:5.1.1 For linear reciprocating wear motion applications, refer to Annex A1.5.1.2 For fixed-bearing ball-cup (“hip-type”) wear motion applications, refer to Annex A2.5.1.3 For nominally linear mot
23、ion delamination wear applications, refer to Annex A3.NOTE 2Other types of applications may be addressed in later revisions.5.2 Lubricant (see also Annex A4):5.2.1 The specimen shall be lubricated with bovine blood serum unless an alternative medium can be justified as described insection 5.2.8. Sin
24、ce different sera differ in composition (protein concentration, etc.), and so forth), dilution with deionized waterof up to 75 % (volume fraction) may be appropriate.The appropriate dilution shall be based on satisfaction of the clinical validationcriteria in the appropriate annex.5.2.2 Afilter-ster
25、ilized serum rather than pooled serum should be used since the former is less likely to contain hemolyzed bloodmaterial, which has been shown to adversely affect the lubricating properties of the serum (12) Serum must be filtered to removehard, abrasive, particulate contaminants that might otherwise
26、 affect the wear properties of the specimens being tested.5.2.3 Maintain the volume, concentration, and temperature of the lubricant nearly constant throughout the test. This may beaccomplished by sealing the chambers so that water does not evaporate, by periodically or continuously replacing evapor
27、ated waterwith deionized water, or by recirculating the lubricant in a sealed environment.5.2.4 To retard bacterial degradation, freeze and store the serum until needed for testing. In addition, it is recommended thatthe serum contains a mass fraction of between -10 and -40 C until it is used for te
28、sting. Prior to testing, it is recommended, butnot mandatory, that a suitable antibacterial agent be added at an appropriate volume fraction.Acommonly used antibacterial agentis sodium azide. If sodium azide is used, it is recommended to use a volume fraction of 0.11 to 0.16 % (mass fraction of 0.2
29、to0.3 % sodium azide (or other suitable antibacterial agent) to minimize bacterial degradation.%). The volume and mass fractionsof the antibacterial agent references the volume and mass of the final test solution which may be diluted or undiluted serum.NOTE 3Sodium azide is a poison and must be hand
30、led very carefully.NOTE 4It has been shown that the addition of sodium azide may reduce wear, and sodium azide may not inhibit all types of bacterial growth (3).5.2.5 It is recommended recommended, but not mandatory, that ethylene-diaminetetraacetic acid (EDTA) be added to the serumat a concentratio
31、n of 20 mM 7.45 g/L to bind calcium in solution and minimize precipitation of calcium phosphate onto the3 The boldface numbers in parentheses refer to a list of references at the end of this test method.F732 172bearing surfaces. The latter event has been shown to strongly affect the friction and wea
32、r properties, particularly ofpolyethylene/ceramic combinations (24). The molar concentration of the EDTA references the volume of the final test solutionwhich may be diluted or undiluted serum.NOTE 5There are multiple forms of EDTA commonly available, such as pure EDTA, EDTA dipostassium salt dihydr
33、ate, and so forth. All of thesecompounds have different molecular weights, and a different amount of each compound is required to achieve the same EDTAconcentration. Pure EDTAhas a very low solubility in water, and EDTA disodium salt dihydrate is recommended.5.2.6 Additives such as sodium azide and
34、EDTAshall be dissolved in deionized water and passed through a 0.2-m filter beforeadding to bovine serum.5.2.7 The appropriate interval for replacing used serum depends on how long the serum maintains its composition (for example,lubricating properties) under the specific test conditions/materials b
35、eing used and the additives present in the serum. There is nominimum replacement interval. The maximum replacement interval is two weeks. The selected interval must meet the validationrequirements in the appropriate annex.5.2.8 A lubricant other than bovine serum shall be used only when it can be sh
36、own that the lubricant reproduces clinical wearmechanisms as well or better than bovine serum. In such case the lubricant shall be specified in the test report.6. Preparation of Specimens6.1 The governing rule for specimen preparation is that the fabrication process parallels that used or intended f
37、or use in theproduction of actual prostheses, in order to produce a specimen with comparable bulk material properties and surfacecharacteristics (see Practice F86).6.2 Polymers and Composites:6.2.1 Obtain a fabrication history for each polymeric or composite specimen, including information such as g
38、rade, batchnumber, and processing variables, including method of forming (extruding, molding, etc.), and so forth), temperature, pressure, andforming time used, articulation surface preparation methods (see Annex A5) and any post-forming treatments, includingsterilization.6.2.2 Pre-test characteriza
39、tion may include measurement of bulk material properties, such as molecular-weight range anddistribution, percent crystallinity, density, or others. The surface finish of specimens may be characterized by profilometry,photomicrography, replication by various plastics, or other techniques.6.2.3 Steri
40、lizationSterilize the specimens in a manner typical of that in clinical use for such devices unless it can be proventhat this has no effect on wear properties of the materials. Report sterilization processing parameters with the aging time prior toeach test, if known. Sterilization of all test and c
41、ontrol specimens within a specific test group should be done simultaneously (ina single container), when possible, to minimize variation among the specimens.6.2.4 Cleaning of Polymer SpecimensPrior to wear testing, careful cleaning of the polymer specimens is important to removeany contaminants that
42、 would not normally be present on an actual prosthesis. During the wear test, the specimens must bere-cleaned and dried before each wear measurement to remove any extraneous material that might affect the accuracy of themeasurement. The required procedure for cleaning and drying of polymeric specime
43、ns, as defined in Practice F2025, is given inAnnex A6.6.3 Soaking of Polymeric and Composite Specimens:6.3.1 Polymeric and composite specimens should be presoaked in the wear test lubricant to minimize fluid-sorption during thewear test. Without presoaking, specimens made from very low-wear polymers
44、 such as UHMWPE could show a net increase inweight or volume during the initial wear intervals due to fluid sorption (12, 35). The error due to fluid sorption can be reducedthrough presoaking and use of control soak specimens. The length of presoaking depends on the variability and magnitude of flui
45、dsorption encountered (35). A minimum of one control soak specimen per material condition is required.6.4 Counterfaces of Metal Alloys, Ceramic, or Other Materials:6.4.1 CharacterizationPretest characterization of the counterface material shall include recording of fabrication variables,such as comp
46、osition, forming method (forging, casting, molding, etc.) and and so forth) and any postforming processing, such asannealing. Obtain data on material properties relevant to wear (for example, grain structure, hardness, and percentage ofcontaminants).6.4.2 Surface FinishIn tests that are intended to
47、evaluate an alternate counterface material bearing against the standardUHMWPE, ensure that the counterface finish is appropriate for components intended for clinical use. In test of alternate materialswhere a reference metal or ceramic is used, polish the counterface to the prosthesis quality.6.4.3
48、Ensure that cleaning of specimens produces a surface free of any particles, oils, greases, or other contaminants that mightinfluence the wear process.7. Procedure7.1 Make any initial measurements required to determine the subsequent amount of wear of the polymeric specimen (seePractice F2025 for the
49、 gravimetric measurement method).F732 1737.2 Place the control soak specimen(s) in a soak chamber of test lubricant, such that the total surface area exposed to thelubricant is equal to that of the wear specimens when mounted in the test chambers. Maintain the soak chamber lubricanttemperature at the same nominal temperature as the test chambers. This temperature shall be 37 6 3C unless justification can beprovided that use of a different temperature will not affect the results.7.3 Place the wear test specimens in their test chambers, add the lubricant, and acti
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