1、Designation: F2346 18Standard Test Methods forStatic and Dynamic Characterization of Spinal ArtificialDiscs1This standard is issued under the fixed designation F2346; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、 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 specify the materials and methodsfor the static and dynamic testing of artificial intervertebraldiscs.1
3、.2 These test methods are intended to provide a basis forthe mechanical comparison among past, present, and futurenon-biologic artificial intervertebral discs. These test methodsallow comparison of artificial intervertebral discs with differentintended spinal locations (cervical, thoracic, and lumba
4、r) andmethods of application to the intervertebral spaces. These testmethods are intended to enable the user to mechanicallycompare artificial intervertebral discs and do not purport toprovide performance standards for artificial intervertebraldiscs.1.3 These test methods describe static and dynamic
5、 tests byspecifying load types and specific methods of applying theseloads. These tests are designed to allow for the comparativeevaluation of artificial intervertebral discs.1.4 These test methods do not purport to address all clini-cally relevant failure modes for artificial intervertebral discs,s
6、ome of which will be device specific. For example, these testmethods do not address the implants resistance to expulsion orimplant wear resistance under expected in vivo loads andmotions. In addition, the biologic response to wear debris is notaddressed in these test methods.1.5 Requirements are est
7、ablished for measuringdisplacements, determining the yield load or moment, andevaluating the stiffness of artificial intervertebral discs.1.6 Some artificial intervertebral discs may not be testablein all test configurations.1.7 The values stated in SI units are to be regarded as thestandard with th
8、e exception of angular measurements, whichmay be reported in terms of either degrees or radians.1.8 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 safety, health, and
9、 environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.9 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International S
10、tandards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2E4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE466 Practice for Conducti
11、ng Force Controlled ConstantAmplitude Axial Fatigue Tests of Metallic MaterialsE467 Practice for Verification of Constant Amplitude Dy-namic Forces in an Axial Fatigue Testing SystemE468 Practice for Presentation of Constant Amplitude Fa-tigue Test Results for Metallic MaterialsE1823 Terminology Rel
12、ating to Fatigue and Fracture TestingF1582 Terminology Relating to Spinal ImplantsF2077 Test Methods for Intervertebral Body Fusion Devices3. Terminology3.1 All definitions below supersede definitions containedwithin Terminologies E6, E1823, F1582, and Practices E466,E467.3.2 Definitions:3.2.1 artif
13、icial intervertebral disca synthetic structure thatis permanently implanted in the disc space between twoadjacent vertebral bodies to provide spinal column support andallow intervertebral motion.3.2.2 coordinate system/axesthree orthogonal axes aredefined by Terminology F1582. The center of the coor
14、dinate1These test methods are under the jurisdiction of ASTM Committee F04 onMedical and Surgical Materials and Devices and is the direct responsibility ofSubcommittee F04.25 on Spinal Devices.Current edition approved June 1, 2018. Published August 2018. Originallyapproved in 2005. Last previous edi
15、tion approved in 2011 as F2346 05 (2011).DOI: 10.1520/F2346-18.2For 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 websit
16、e.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of Int
17、ernational Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1system is located at the geometric center of the artificialintervertebral disc.Alternative coordinate systems may be usedwith justification. The XY-plane is to bisect
18、the superior andinferior surfaces that are intended to simulate the adjacentvertebral end plates. The positive Z-axis is to be directedperpendicular to the bisector of the disc space, oriented in thesuperior direction. The positive X-axis is parallel to theintervertebral space, oriented in the anter
19、ior direction and thepositive Y-axis is parallel to the disc space, oriented in the leftdirection. Force components parallel to the XY-plane are shearcomponents of loading. The compressive axial force is definedto be the component in the negative Z direction. Torsional loadis defined to be the compo
20、nent of moment parallel to theZ-axis.3.2.3 fatigue lifethe number of cycles, N, that the artificialintervertebral disc can sustain at a particular load or momentbefore functional failure occurs.3.2.4 functional failurepermanent deformation that ren-ders the artificial intervertebral disc ineffective
21、 or unable toadequately resist load.3.2.5 ideal insertion locationthe location of the artificialdisc in the intervertebral space that is suggested in themanufacturers surgical installation instructions. The idealinsertion location is to be described with respect to thesimulated inferior and superior
22、 vertebral bodies (polyacetal ormetal blocks) and will be dictated by the device design.3.2.6 intended method of applicationartificial interverte-bral discs may contain different types of features to stabilizethe implant-tissue interface such as threads, spikes, and tex-tured surfaces. Each type of
23、feature has an intended method ofapplication or attachment to the spine.3.2.7 intended spinal locationthe anatomic region of thespine intended for the artificial intervertebral disc. Artificialintervertebral discs may be designed and developed for specificregions of the spine such as the cervical, t
24、horacic, and lumbarspine. Also, since different surgical approaches may exist, thedescription of the intended spinal location should include boththe indicated spinal levels and the ideal insertion locationswithin the intervertebral space allowed at each level.3.2.8 intervertebral heightthe minimum d
25、istance parallelto the Z-axis in the YZ-plane between the unaltered simulatedvertebral bodies: minimum height of 2 mm and maximumheight of 16.5 mm.3,4See Fig. 1.3.2.9 load pointthe point through which the resultantforce on the intervertebral device passes; that is, the geometriccenter of the superio
26、r fixtures sphere (see Figs. 2-4).3.2.10 maximum run-out load or momentthe maximumload or moment for a given test that can be applied to anartificial intervertebral disc where all of the tested constructshave withstood 10 000 000 cycles without functional failure.3.2.11 mechanical deteriorationdeter
27、ioration that is vis-ible to the naked eye and is associated with mechanical damageto the device under test (for example, initiation of fatigue crackor surface wear).3.2.12 offset angular displacement(distance OBFig. 6)offset on the angular displacement axis equal to 2 % of theintervertebral height,
28、 H, divided by the maximum radius of theimplant in the XY-plane; for example, for an artificial interver-tebral disc with a height of 10 mm and a maximum radius inthe XY-plane of 9 mm, distance OB = (0.02) (10 mm) / (9 mm)= 0.022 radians = 1.3.3.2.13 offset displacement(distance OBFig. 6) offset ont
29、he linear displacement axis equal to 2 % of the intervertebralheight (for example, 0.2 mm for a 10 mm intervertebralheight).3.2.14 permanent deformationthe remaining linear or an-gular displacement (axialmm, angulardegrees or radians)relative to the initial unloaded condition of the artificialinterv
30、ertebral disc after the applied load or moment has beenremoved.3.2.15 stiffness (axialn/mm, angularnmm/degree ornmm/radian)the slope of the initial linear portion of the3Nissan, M., Gilad, I., “The Cervical and Lumbar VertebraeAn Anthropomet-ric Model,” Engineering In Medicine, Vol 13, No. 3, 1984,
31、pp. 111114.4Lu, J., Ebraheim, N.A., Yang, H., Rollins, J., and Yeasting, R. A., “AnatomicBases forAnterior Spinal Surgery: SurgicalAnatomy of the Cervical Vertebral Bodyand Disc Space,” Surg Radiol Anat, Vol 21, No. 4, 1999, pp. 235239.FIG. 1 Intervertebral Height DiagramF2346 182load-displacement c
32、urve or the slope of the initial linearportion of the moment-angular displacement curve. This isillustrated as the slope of the line OG in Fig. 6. If the devicedoes not exhibit a linear initial load/displacement curve, thedisplacement should be reported at 30 %, 60 %, and 90 % ofthe yield load or mo
33、ment.3.2.16 test blockthe component of the test apparatus formounting the artificial intervertebral disc in the intended testconfiguration.3.2.17 ultimate displacement (axialmm, angulardegrees or radians)the linear or angular displacement asso-ciated with the ultimate load or ultimate moment. This i
34、sillustrated as the displacement, OF, in Fig. 6.3.2.18 ultimate load or moment (axialn, angularnmm)the maximum applied load, F, or moment, M, trans-mitted by the pushrod (assumed equal to force and momentcomponent parallel to and indicated by load or torque cell) tothe artificial intervertebral disc
35、 assembly. This is illustrated aspoint E in Fig. 6.3.2.19 yield displacementthe linear displacement (mm) orangular displacement (degrees or radians) when an artificialintervertebral disc has a permanent deformation equal to theoffset displacement or offset angular displacement. This isillustrated as
36、 the distance OA in Fig. 6.3.2.20 yield load or momentthe applied load, F,ormoment, M, transmitted by the pushrod (assumed equal toforce component parallel to and indicated by load or torquecell) required to produce a permanent deformation equal to theoffset displacement or the offset angular displa
37、cement. This isillustrated as point D in Fig. 6.4. Summary of Test Methods4.1 These test methods are proposed for the mechanicaltesting of artificial intervertebral discs specific to the cervical,thoracic, and lumbar spine.4.2 All tests are to be performed on the prosthesis size withthe smallest saf
38、ety factor for the levels indicated for implan-tation. If this worst-case size cannot be determined usingtheoretical or experimental methods such as simple stresscalculations or finite element analysis, then all available sizesare to be tested and the complete range of results are to bereported.4.3
39、Fatigue testing of the artificial intervertebral discs willsimulate a motion segment via a gap between two polyacetalFIG. 2 Compression Testing ConfigurationF2346 183test blocks. The polyacetal will eliminate the effects of thevariability of bone properties and morphology for the fatiguetests. The m
40、inimum ultimate tensile strength of the polyacetalblocks shall be no less than 61 MPa.4.4 Static testing of the artificial intervertebral discs willsimulate a motion segment via a gap between two stainlesssteel blocks. The minimum tensile yield strength of the blocksshall be no less than 1170 MPa.4.
41、5 The pushrod shall be manufactured from stainless steelhaving minimum tensile yield stress of 1170 MPa and be ofminimum cross-sectional area that would produce a compres-sive yield strength of at least 25 000 N.4.6 Static and dynamic tests will evaluate the artificialintervertebral disc. The user o
42、f these test methods must decidewhich series of tests are applicable to the artificial interverte-bral disc in question. The user of these test methods maychoose to use all or a selection of the tests described in thesetest methods for testing a particular artificial intervertebraldisc. For example,
43、 the torsion test method may not apply to adevice that has no mechanical resistance in axial rotation.5. Significance and Use5.1 Artificial intervertebral discs are orthopaedic implantsthat replace degenerated natural intervertebral discs. Theirfunction is to support the anterior column of the spine
44、 whileallowing motion at the operated level. These test methodsoutline materials and methods for the characterization of themechanical performance of different artificial intervertebraldiscs so that comparisons can be made between differentdesigns.5.2 These test methods are designed to quantify the
45、staticand dynamic characteristics of different designs of artificialintervertebral discs. These tests are conducted in vitro in orderto allow for analysis of individual disc replacement devices andcomparison of the mechanical performance of multiple artifi-cial intervertebral disc designs in a stand
46、ard model.5.3 The loads applied to the artificial intervertebral discsmay differ from the complex loading seen in vivo, andtherefore, the results from these tests may not directly predictin vivo performance. The results, however, can be used tocompare mechanical performance of different artificial i
47、n-tervertebral discs.5.4 Fatigue tests should be conducted in a 0.9 % salineenvironmental bath at 37C at a rate of 2 Hz or less. Other testenvironments such as a simulated body fluid, a saline drip ormist, distilled water, or other type of lubrication could also beused with adequate justification. L
48、ikewise, alternative testfrequencies may be used with adequate justification.FIG. 3 Compression/Shear Testing ConfigurationF2346 1845.5 It is well known that the failure of materials is depen-dent upon stress, test frequency, surface treatments, and envi-ronmental factors. Therefore, when determinin
49、g the effect ofchanging one of these parameters (for example, frequency,material, or environment), all others should be kept constant tofacilitate interpretation of the results. In particular, it may beFIG. 4 Torsion Testing Configuration with a Pin-Slot GimbalFIG. 5 Polyacetal or Metal Test BlockF2346 185necessary to assess the influence of test frequency on devicefracture while holding the test environment, implant materialsand processing, and implant geometry constant.6. Apparatus6.1 Test machines will conform to the requirements ofP
