1、Designation: F1714 96 (Reapproved 2013)Standard Guide forGravimetric Wear Assessment of Prosthetic Hip Designs inSimulator Devices1This standard is issued under the fixed designation F1714; the number immediately following the designation indicates the year oforiginal adoption or, in the case of rev
2、ision, 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 guide describes a laboratory method using aweight-loss technique for evaluating the wear prope
3、rties ofmaterials or devices, or both, which are being considered foruse as bearing surfaces of human-hip-joint replacement pros-theses. The hip prostheses are evaluated in a device intended tosimulate the tribological conditions encountered in the humanhip joint, for example, use of a fluid such as
4、 bovine serum, orequivalent pseudosynovial fluid shown to simulate similarwear mechanisms and debris generation as found in vivo, andtest frequencies of 1 Hz or less.1.2 Since the hip simulator method permits the use of actualimplant designs, materials, and physiological load/motioncombinations, it
5、can represent a more physiological simulationthan basic wear-screening tests, such as pin-on-disk (seePractice F732) or ring-on-disk (see ISO 6474).1.3 It is the intent of this guide to rank the combination ofimplant designs and materials with regard to material wear-rates, under simulated physiolog
6、ical conditions. It must berecognized, however, that there are many possible variations inthe in vivo conditions, a single laboratory simulation with afixed set of parameters may not be universally representative.1.4 The reference materials for the comparative evaluationof candidate materials, new d
7、evices, or components, or acombination thereof, shall be the wear rate of extruded orcompression-molded, ultra-high molecular weight (UHMW)polyethylene (see Specification F648) bearing against standardcounter faces stainless steel (see Specification F138); cobalt-chromium-molybdenum alloy (see Speci
8、fication F75); thermo-mechanically processed cobalt chrome (see SpecificationF799); alumina ceramic (see Specification F603), havingtypical prosthetic quality, surface finish, and geometry similarto those with established clinical history. These referencematerials will be tested under the same wear
9、conditions as thecandidate materials.1.5 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.2. Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsF75 Specification for Cobalt-28 Chromium-6 MolybdenumAlloy
10、Castings and Casting Alloy for Surgical Implants(UNS R30075)F86 Practice for Surface Preparation and Marking of Metal-lic Surgical ImplantsF136 Specification for Wrought Titanium-6Aluminum-4Vanadium ELI (Extra Low Interstitial)Alloy for SurgicalImplant Applications (UNS R56401)F138 Specification for
11、 Wrought 18Chromium-14Nickel-2.5Molybdenum Stainless Steel Bar and Wire for SurgicalImplants (UNS S31673)F370 Specification for Proximal Femoral Endoprosthesis(Withdrawn 2005)3F565 Practice for Care and Handling of Orthopedic Implantsand InstrumentsF603 Specification for High-Purity Dense Aluminum O
12、xidefor Medical ApplicationF648 Specification for Ultra-High-Molecular-Weight Poly-ethylene Powder and Fabricated Form for Surgical Im-plantsF732 Test Method for Wear Testing of Polymeric MaterialsUsed in Total Joint ProsthesesF799 Specification for Cobalt-28Chromium-6Molybdenum1This guide is under
13、the jurisdiction of ASTM Committee F04 on Medical andSurgical Materials and Devices and is the direct responsibility of SubcommitteeF04.22 on Arthroplasty.Current edition approved March 15, 2013. Published April 2013. Originallyapproved in 1996. Last previous edition approved in 2008 as F1714 96 (20
14、08).DOI: 10.1520/F1714-96R13.2For 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.3The last approved version of th
15、is historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1Alloy Forgings for Surgical Implants (UNS R31537,R31538, R31539)G40 Terminology Relating to Wear and Erosion2.2 ISO Standard:ISO 6474
16、Implants for SurgeryCeramic Materials Based onAlumina43. Significance and Use3.1 This guide uses a weight-loss method of wear determi-nation for the polymeric components used with hip jointprostheses, using serum or demonstrated equivalent fluid forlubrication, and running under a dynamic load profi
17、le repre-sentative of the human hip-joint forces during walking (1,2).5The basis for this weight-loss method for wear measurementwas originally developed (3) for pin-on-disk wear studies (seePractice F732) and has been extended to total hip replacements(4,5) femoral-tibial knee prostheses (6), and t
18、o femoropatellarknee prostheses (6,7).3.2 While wear results in a change in the physical dimen-sions of the specimen, it is distinct from dimensional changesdue to creep or plastic deformation, in that wear generallyresults in the removal of material in the form of polymericdebris particles, causing
19、 a loss in weight of the specimen.3.3 This guide for measuring wear of the polymeric com-ponent is suitable for various simulator devices. These tech-niques can be used with metal, ceramic, carbon, polymeric, andcomposite counter faces bearing against a polymeric material(for example, polyethylene,
20、polyacetal, and so forth). Thisweight-loss method, therefore, has universal application forwear studies of total hip replacements that feature polymericbearings. This weight-loss method has not been validated forhigh-density material bearing systems, such as metal-metal,carbon-carbon, or ceramic-cer
21、amic. Progressive wear of suchrigid bearing combinations generally has been monitored usinga linear, variable-displacement transducers or by other profi-lometric techniques.4. Apparatus and Materials4.1 Hip Prosthesis ComponentsThe hip-joint prosthesiscomprises a ball-and-socket configuration in whi
22、ch materialssuch as polymers, composites, metal alloys, ceramics, andcarbon have been used in various combinations and designs.4.2 Component ConfigurationsThe diameter of the pros-thetic ball may vary from 22 to 54 mm or larger. The designmay include ball-socket, trunnion, bipolar, or other configur
23、a-tions.4.3 Hip Simulator:4.3.1 Test ChambersIn the case of a multi-specimenmachine, contain the components in individual, isolated cham-bers to prevent contamination of one set of components withdebris from another test. Ensure that the chamber is madeentirely of noncorrosive materials, such as acr
24、ylic plastic orstainless steel, and is easily removable from the machine forthorough cleaning between tests. Design the wear chamberssuch that the test bearing surfaces are immersed in the lubricantthroughout the test (3,7).4.3.2 Component Clamping FixturesSince wear is to bedetermined from the weig
25、ht-loss of the components, themethod for mounting the components in the test chambershould not compromise the accuracy of assessment of theweight-loss due to wear.4.3.3 LoadEnsure that the test load profile is representa-tive of that which occurs during the patients walking cycle,with peak hip-loads
26、 2kN(2). The loading apparatus shall befree to follow the specimen as wear occurs, so that the appliedload is constant to within 63 % for the duration of the test.Never allow the applied load to be below that required to keepthe chambers seated (for example, 50 N) (4).4.3.4 MotionEnsure that relativ
27、e motion between the hipcomponents oscillates and simulates the flexion-extension arcof walking. Addition of internal-external or abduction-adduction arcs is at the investigators discretion. It is recom-mended that the orientations of the cup and ball relative to eachother and to the load-axis be ma
28、intained by suitable specimen-holder keying.4.3.5 Oscillating FrequencyOscillate the hip prostheses ata rate of one cycle per second (1 Hz).4.3.6 Cycle CounterInclude a counter with the hip-simulator to record the total number of wear cycles.4.3.7 FrictionIt is recommended that the machine includese
29、nsors capable of monitoring the friction forces transmittedacross the bearing surfaces during the wear test.4.4 Lubricant:4.4.1 It is recommended that the specimen be lubricatedwith bovine blood serum; however, another suitable lubricationmedium may be used if validated.4.4.2 If serum is used, use f
30、iltered-sterilized serum ratherthan pooled serum since the former is less likely to containhemolyzed blood material, which has been shown to adverselyaffect the lubricating properties of the serum (3). Dilutedsolutions of serum have also been used for this purpose (8).Filtration may remove hard, abr
31、asive, particulate contaminantsthat might otherwise affect the wear properties of the speci-mens being tested.4.4.3 Maintain the volume and concentration of the lubri-cant nearly constant throughout the test. This may be accom-plished by sealing the chambers so that water does notevaporate, or perio
32、dically or continuously replacing evaporatedwater with distilled water.4.4.4 To retard bacterial degradation, freeze and store theserum until needed for the test. In addition, ensure that the fluidmedium in the test contains 0.2 % sodium azide (or othersuitable antibiotic) to minimize bacterial degr
33、adation. Otherlubricants should be evaluated to determine appropriate storageconditions.4.4.5 It is recommended that ethylene-diaminetetraaceticacid (EDTA) be added to the serum at a concentration of 20mM to bind calcium in solution and minimize precipitation ofcalcium phosphate onto the bearing sur
34、faces. The latter eventhas been shown to strongly affect the friction and wear4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.5The boldface numbers in parentheses refer to the list of references at the end ofthis standard
35、.F1714 96 (2013)2properties, particularly of polyethylene/ceramic combinations.The addition of EDTA to other lubricant mediums should beevaluated.4.4.6 A lubricant other than bovine serum may be used if itcan be shown that its lubricating properties and, therefore,material wear properties are reason
36、ably physiological (8).Insuch a case, specify the lubricant in the test report.4.5 Hold the bulk temperature of the lubricant at 37 6 3Cor as specified, if different.5. Specimen Preparation5.1 The governing rule for preparation of component coun-ter faces is that the fabrication process parallels th
37、at used orintended for use in the production of actual prostheses, in orderto produce a specimen with comparable bulk material proper-ties and surface characteristics (see Practice F86).5.2 Polymers and Composites:5.2.1 Obtain a fabrication history for each polymeric orcomposite component, including
38、 information such as grade,batch number, and processing variables, including method offorming (extruding, molding, and so forth), temperature,pressure, and forming time used, and any post-formingtreatments, including sterilization.5.2.2 Pretest characterization may include measurement ofbulk materia
39、l properties, such as molecular-weight range anddistribution, percent crystallinity, density, or other. The surfacefinish of specimens may be characterized by profilometry,photomicrography, replication by various plastics, or othertechniques.5.2.3 SterilizationSterilize the components in a mannertyp
40、ical of that in clinical use for such devices, including totaldose and dose rate, as these may affect the wear properties ofthe materials. Report these processing parameters with theaging time prior to each test when known. Sterilization of alltest and control components within a specific test group
41、 shouldbe done simultaneously (in a single container), when possible,to minimize variation among the specimens. This wear-simulation procedure makes no attempt to maintain the sterilityof specimens during the wear test.5.2.4 Cleaning of Polymer ProsthesesPrior to weartesting, careful cleaning of the
42、 polymer specimens is importantto remove any contaminants that would not normally bepresent on the actual prosthesis. During the wear run, thecomponents must be re-cleaned and dried before each weigh-ing to remove any extraneous material that might affect theaccuracy of the weighing. A suggested pro
43、cedure for cleaningand drying of polymeric components is given in Annex A4.With some combinations of materials, wear may result in thetransfer of particulate debris which may then become re-imbedded or otherwise attached to polymeric, metal, or com-posite surfaces. Such an occurrence will render the
44、 weight-lossassessment of wear less reliable.5.2.5 Weighing of Polymeric ComponentsWeigh the poly-meric components on an analytical balance having an accuracyon the order of 610 g. This degree of sensitivity is necessaryto detect the slight loss in weight of polymers, such as UHMWpolyethylene, which
45、 may wear 30 mg or less per million cycles(3,5).Always weigh specimens in the clean, dry condition (seeAnnex A1). Keep the components in a dust-free container andhandle with clean tools to prevent contamination that mightaffect the weight measurement. Weigh each wear and controlcomponent three times
46、 in rotation to detect random errors inthe weighing process.5.3 Soaking of Polymeric and Composite Prostheses:5.3.1 Polymeric and composite components should be pre-soaked in the lubricant to minimize fluid sorption during thewear run. Without presoaking, components of very low-wearpolymers such as
47、polyethylene may show a net increase inweight during the initial wear intervals, due to fluid sorption(3,4). The error due to fluid sorption can be reduced throughpresoaking and the use of control soak specimens. The numberof specimens required and the length of presoaking depends onthe variability
48、and magnitude of fluid sorption encountered (4).5.3.2 After fabrication and characterization, clean and drythe wear components and three soak-control components ofeach test material in accordance with Annex A4, and thenweigh by precisely controlled and repeatable methods. Placethe wear components an
49、d soak controls in a container of serumfor a specified time interval. Then, remove, clean, dry, andreweigh the components, and calculate the weight-loss (seeAnnex A4). Repeat the specimens until a steady rate offluid-sorption has been established. The number of weighingswill depend on the amount of fluid sorption exhibited by thespecimens.5.3.3 In general, the weight of the components will stabilizeat an asymptotic value in a reasonable time period. WithUHMW polyethylene, a presoak period of 30 days has beenfound adequate (4,7). In any case, use the weight-gain
