1、Designation: F2423 11Standard Guide forFunctional, Kinematic, and Wear Assessment of Total DiscProstheses1This standard is issued under the fixed designation F2423; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last r
2、evision. 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 provides guidance for wear and/or fatiguetesting of total disc prostheses under functional and kinematiccondition
3、s and, to this end, describes test methods for assess-ment of the wear or functional characteristics, or both, of totaldisc prostheses.1.2 Both lumbar and cervical prostheses are addressed.1.3 Load and kinematic profiles for lumbar and cervicaldevices are not identical and, therefore, are addressed
4、sepa-rately in the guide.1.4 Partial disc replacements, such as nucleus replacementsor facet joint replacements, are not intended to be addressed.1.5 Wear is assessed using a weight loss method in a testingmedium as defined in this guide.1.6 This guide does not address any potential failure modeas i
5、t relates to the fixation of the implant to its bony interfaces.1.7 It is the intent of this guide to enable comparison ofintervertebral disc (IVD) prostheses with regard to wear andfatigue characteristics when tested under the specified condi-tions. It must be recognized, however, that there are ma
6、nypossible variations in the in vivo conditions.Asingle laboratorysimulation with a fixed set of parameters might not beuniversally representative.1.8 Most IVD prostheses primarily fall into two classifica-tions: articulating ball-in-socket type prostheses, and elasto-meric or compliant type prosthe
7、ses. For the former, this guideprimarily addresses Mode 1 wear (defined herein); whereas forthe latter, this guide addresses potential failure of the prosthesiswhen the implant is subjected to a range of motion and/or loadsthat fall within the full range of possible physiologic motionsand loads.1.9
8、For articulating components, this guide predominantlydescribes a Mode 1 test. The user is cautioned that other modesof wear may occur and may have significant influence on thefunctionality and performance of an articulating IVD prosthe-sis, and therefore the user should consider the effects of other
9、wear modes on the performance of the prosthesis.1.10 In order that the data be reproducible and comparablewithin and between laboratories, it is essential that uniformprocedures are established. This guide is intended to facilitateuniform methods for testing and reporting of data for total discrepla
10、cement prostheses.1.11 Without a substantial clinical retrieval history of IVDprostheses, actual loading profiles and patterns cannot bedelineated at the time of the writing of this guide. It thereforefollows that the load and motion conditions specified by thisguide do not necessarily accurately re
11、produce those occurringin vivo. Rather, this guide provides useful boundary/endpointconditions for evaluating prosthesis designs in a functionalmanner.1.12 The values stated in SI units are to be regarded as thestandard with the exception of angular measurements, whichmay be reported in either degre
12、es or radians.1.13 This guide is not intended to be a performance stan-dard. It is the responsibility of the user of this guide tocharacterize the safety and effectiveness of the prosthesis underevaluation.1.14 This standard does not purport to address all of thesafety concerns, if any, associated w
13、ith its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2F561 Practice for Retrieval and Analysis of Medical De-vices, and
14、 Associated Tissues and FluidsF1582 Terminology Relating to Spinal ImplantsF1714 Guide for Gravimetric Wear Assessment of Pros-thetic Hip Designs in Simulator DevicesF1877 Practice for Characterization of ParticlesF2077 Test Methods For Intervertebral Body Fusion De-vices1This guide is under the jur
15、isdiction of ASTM Committee F04 on Medical andSurgical Materials and Devices and is the direct responsibility of SubcommitteeF04.25 on Spinal Devices.Current edition approved July 1, 2011. Published August 2011. Originallyapproved in 2005. Last previous edition approved in 2005 as F2423 05. DOI:10.1
16、520/F2423-11.2For 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.1Copyright ASTM International, 100 Barr Harbor D
17、rive, PO Box C700, West Conshohocken, PA 19428-2959, United States.2.2 ISO Standard:3ISO 181921 Implants for SurgeryWear of Total Interver-tebral Spinal Disc ProsthesesPart 1: Loading and Dis-placement Parameters for Wear Testing and Correspond-ing Environmental Conditions for Test3. Terminology3.1
18、DefinitionsAll functional and kinematic testing termi-nology is consistent with the referenced standards (for ex-ample, Test Methods F2077, Terminology F1582, and so forth),unless otherwise stated.3.1.1 axial load, nthe resultant force Faxialapplied to thesuperior or inferior fixture-end plate that
19、simulates the in vivoload that an IVD prosthesis (original healthy disc) must resist.3.1.1.1 DiscussionBased on a healthy disc, the primarycomponent would be an axial compressive force FZin thedirection of the negative global Z axis, and it would passthrough the origin of the IVD prosthesis. Shear c
20、omponents inthe XY plane would be FXand FY. Lateral bending moment MXand flexion/extension moment MYcomponents would be cre-ated about the origin when the axial load does not pass throughit.3.1.2 coordinate system/axes, nglobal XYZ orthogonalaxes are defined following a right-handed Cartesian coordi
21、natesystem in which the XY plane is to bisect the sagittal planeangle between superior and inferior surfaces that are intendedto simulate the adjacent vertebral end plates. The global axesare stationary relative to the IVD prostheses inferior end platefixture, which, in this guide, is also considere
22、d to be stationarywith respect to the test machines frame. Lower case letters,xyz, denote a local, moving orthogonal coordinate systemattached to the superior end plate fixture with directionsinitially coincident with those of the global XYZ axes, respec-tively. The 3-D motion of the superior relati
23、ve to inferior endplate fixture is specified and is to be measured in terms ofsequential Eulerian angular rotations about the xyz axes,respectively (z, axial rotation; x, lateral bending; and y,flexion-extension).3.1.2.1 origin, ncenter of the global coordinate system islocated at the initial positi
24、on of the total disc replacementsinstantaneous center of rotation (COR).3.1.2.2 DiscussionSome articulating devices do not havea single center of rotation, but instead have either a mobilecenter of rotation or multiple distinct centers of rotation,depending on the direction of movement. In this case
25、, theorigin should be explicitly defined by the user with a rationalefor that definition.3.1.2.3 X-axis, npositive X-axis is a global fixed axisrelative to the test machines stationary base, and is to bedirected anteriorly relative to the specimens initial unloadedposition.3.1.2.4 Y-axis, npositive
26、Y-axis is a global fixed axisrelative to the test machines stationary base, and is directedlaterally relative to the specimens initial unloaded position.3.1.2.5 Z-axis, npositive Z-axis is a global fixed axisrelative to the test machines stationary base, and is to bedirected superiorly relative to t
27、he specimens initial unloadedposition.3.1.2.6 x-axis, npositive x-axis is a fixed axis relative tothe IVD prosthesis and a moving axis relative to the globalcoordinate system, and is directed anteriorly relative to theprosthesis.3.1.2.7 y-axis, npositive y-axis is a fixed axis relative tothe IVD pro
28、sthesis and a moving axis relative to the globalcoordinate system, and is directed laterally relative to theprosthesis.3.1.2.8 z-axis, npositive z-axis is a fixed axis relative tothe IVD prosthesis and a moving axis relative to the globalcoordinate system, and is directed superiorly relative to thep
29、rosthesis.3.1.3 degradation, nloss of material or function or mate-rial properties as a result of causes other than that associatedwith wear.3.1.4 fluid absorption, nfluid absorbed by the devicematerial during testing.3.1.5 functional failure, npermanent deformation or wearthat renders the IVD prost
30、hesis assembly ineffective or unableto resist load/motion or any secondary effects that result in areduction of clinically relevant motions or the motions in-tended by the design of the device.3.1.6 interval net volumetric wear rate VRiduring cycleinterval i (mm3/million cycles), nVRi= WRi/r, where
31、r =mass density (for example, units of g/mm3) of the wearmaterial.3.1.7 interval net wear rate WRiduring cycle interval i(g/million cycles), nWRi=(NWi NWi-1)/(number of cyclesin interval i)3106.3.1.7.1 DiscussionFor i =1,NWi-1=0.3.1.8 intervertebral disc (IVD) prosthesis, nnonbiologicstructure inten
32、ded to restore the support and motion or aportion thereof between adjacent vertebral bodies.3.1.9 kinematic profile, nrelative motion between adja-cent vertebral bodies that the IVD prosthesis is subjected towhile being tested.3.1.10 limit, na significant change in stiffness during agiven motion, in
33、dicating the implant has reached its designedendpoint in range of motion.3.1.11 load profile, nloading that the device experienceswhile being tested under an applied kinematic profile or theloading that the IVD prosthesis is subjected to if tested in loadcontrol.3.1.12 mechanical failure, nfailure a
34、ssociated with adefect in the material (for example, fatigue crack) or of thebonding between materials that may or may not producefunctional failure.3.1.13 Wear modes (1)4for articulating type designs:3.1.13.1 Mode 1 refers to the articulation between twoprimary bearing surfaces only.3Available from
35、 American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.4The boldface numbers in parentheses refer to the list of references at the end ofthis standard.F2423 1123.1.13.2 Mode 2 occurs whenever a primary surface articu-lates directly against a s
36、econdary, nonbearing surface.3.1.13.3 Mode 3 occurs when the two primary bearingsurfaces are still articulating together, but third-body particleshave become entrapped between them.3.1.13.4 Mode 4 refers to any contact and motion occurringbetween two secondary, nonbearing surfaces.3.1.14 net wear NW
37、iof wear specimen (g), n NWi5W0 Wi! 1 Si S0!; loss in weight of the wear specimencorrected for fluid absorption at end of cycle interval i.3.1.15 net volumetric wear NViof wear specimen (mm3),n NVi5 NWi/r at end of cycle interval i where r = massdensity (for example, units of g/mm3) of the wear mate
38、rial.3.1.16 run out (cycles), nmaximum number of cycles thata test needs to be carried to if functional failure has not yetoccurred.3.1.17 wear, nprogressive loss of material from the de-vice(s) as a result of relative motion at the surfaces as measuredby the change in mass of the IVD prosthesis or
39、components ofthe IVD prosthesis.3.1.17.1 DiscussionOr in the case of a nonarticulating,compliant IVD prosthesis, wear is defined simply as the loss ofmaterial from the prosthesis. Note that inferior and superiorbone interface components are excluded from this definition;see 5.2.2.3.1.18 weight Siof
40、soak control specimen (g), nS0initialand Siat end of cycle interval i.3.1.19 weight Wiof wear specimen (g), nW0initial and Wiat end of cycle interval i.4. Significance and Use4.1 This guide can be used to determine the fatigue andwear behavior of IVD prostheses subjected to functional andkinematic c
41、yclic loading/motion for relatively large numbers ofcycles (for example, various designs of IVD prostheses, as wellas the effects of materials, manufacturing techniques and otherdesign variables on one particular design can be determinedusing this guide).4.2 This guide is intended to be applicable t
42、o IVD prosthe-ses that support load and transmit motion by means of anarticulating joint or by use of compliant materials. Ceramics,metals, or polymers, or combination thereof, are used in IVDprosthesis, and it is the goal of this guide to enable a kinematicwear and/or fatigue comparison of these de
43、vices, regardless ofmaterial and type of device.5. Apparatus5.1 Total Disc Prosthesis ComponentsThe total disc re-placement may comprise a variety of shapes and configura-tions. Some known forms include ball-and-socket articulatingjoints, biconcave joints having a free-floating or semi-constrained t
44、hird body, metallic endplates bonded to elastomercores, and single-axis hinge joints.5.2 Spinal Testing Apparatus:5.2.1 Test ChambersIn case of a multispecimen machine,each chamber shall be isolated to prevent cross-contaminationof the test specimens. The chamber shall be made entirely ofnoncorrosiv
45、e components, such as acrylic plastic or stainlesssteel, and shall be easily removable from the machine forthorough cleaning between tests.5.2.2 Component Clamping/FixturingSince the purposeof the test is to characterize the wear and/or fatigue propertiesof the IVD prosthesis under functional and ki
46、nematic condi-tions, the method for mounting components in the test chambershall not compromise the accuracy of assessment of the weightloss or stiffness variation during the test. For example, pros-theses having complicated superior and inferior surfaces forcontacting bone (for example, sintered be
47、ads, hydroxylapatite(HA) coating, plasma spray) may be specially manufactured tomodify that surface in a manner that does not affect the wearsimulation.5.2.3 The device should be securely (rigidly) attached at itsbone-implant interface to the mating test fixtures.5.2.4 The motion of the superior tes
48、t fixture relative to theinferior testing fixture shall be unconstrained in three-dimensional space except for the components in the directionof specified test motions/loads.5.2.5 Load and Motion (components in Table 1 and Table2):5.2.5.1 An axial load is to be a compressive load applied inthe direc
49、tion of the negative Z-axis. Deviations from this as theIVD moves from its initial position are to be reported as shearcomponents FX, FY, and moments MXand MY.5.2.5.2 Flexion load and motion are positive moment, MY,and rotation about the y-axis, respectively.5.2.5.3 Extension load and motion are negative moment,MY, and rotation about the y-axis, respectively.5.2.5.4 Lateral bend load and motion are positive andnegative moments, MX, and rotations about the x-axis, respec-tively.5.2.5.5 Torsional load and motion are positive and neg
