1、Designation: F 2346 05Standard Test Methods forStatic and Dynamic Characterization of Spinal ArtificialDiscs1This standard is issued under the fixed designation F 2346; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of la
2、st revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 intervertebraldisc
3、s.1.2 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 lu
4、mbar) 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 dyna
5、mic 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 disc
6、s,some 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
7、established for measuring displace-ments, determining the yield load or moment, and evaluatingthe 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 wi
8、th the exception of angular measurements, whichmay be reported in terms of either degrees or radians.1.8 The use of this standard may involve the operation ofpotentially hazardous equipment. This standard does not pur-port to address all of the safety concerns, if any, associatedwith its use. It is
9、the responsibility of the user of this standardto establish appropriate safety and health practices anddetermine the applicability of regulatory limitations prior touse.2. Referenced Documents2.1 ASTM Standards:2E4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Method
10、s of Mechanical Test-ingE 466 Practice for Conducting Force Controlled ConstantAmplitude Axial Fatigue Tests of Metallic MaterialsE 467 Practice for Verification of Constant Amplitude Dy-namic Forces in an Axial Fatigue Testing SystemE 468 Practice for Presentation of Constant Amplitude Fa-tigue Tes
11、t Results for Metallic MaterialsE 1823 Terminology Relating to Fatigue and Fracture Test-ingF 1582 Terminology Relating to Spinal ImplantsF 2077 Test Methods for Intervertebral Body Fusion De-vices3. Terminology3.1 DefinitionsAll definitions below supersede definitionscontained within Terminologies
12、E6, E 1823, F 1582, andPractices E 466, E 467.3.1.1 artificial intervertebral disca synthetic structurethat is permanently implanted in the disc space between twoadjacent vertebral bodies to provide spinal column support andallow intervertebral motion.3.1.2 coordinate system/axesthree orthogonal axe
13、s aredefined by Terminology F 1582. The center of the coordinatesystem is located at the geometric center of the artificialintervertebral disc.Alternative coordinate systems may be usedwith justification. The XY-plane is to bisect the superior andinferior surfaces that are intended to simulate the a
14、djacentvertebral end plates. The positive Z-axis is to be directedperpendicular to the bisector of the disc space, oriented in the1These test methods are under the jurisdiction of ASTM Committee F04 onMedical and Surgical Materials and Devices and is the direct responsibility ofSubcommittee F04.25 o
15、n Spinal Devices.Current edition approved Jan. 1, 2005. Published January 2005.2For 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 o
16、nthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.superior direction. The positive X-axis is parallel to theintervertebral space, oriented in the anterior direction and thepositive Y-axis is parallel to the disc space
17、, 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 component of moment parallel to theZ-axis.3.1.3 fatigue lifethe number
18、of cycles, N, that the artificialintervertebral disc can sustain at a particular load or momentbefore functional failure occurs.3.1.4 functional failurepermanent deformation that ren-ders the artificial intervertebral disc ineffective or unable toadequately resist load.3.1.5 ideal insertion location
19、the 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 vertebral bodies (polyacetal ormetal blocks) and will be dictated
20、 by the device design.3.1.6 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 feature has an intended method ofapplication or attachment to the
21、spine.3.1.7 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, thoracic, and lumbarspine. Also, since different surgical approache
22、s 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.3.1.8 intervertebral heightthe minimum distance parallelto the Z-axis in the YZ-plane between the unaltere
23、d simulatedvertebral bodies: minimum height of 2 mm and maximumheight of 16.5 mm.3,4See Fig. 1.3.1.9 load pointthe point through which the resultantforce on the intervertebral device passes; that is, the geometriccenter of the superior fixtures sphere (see Figs. 2-4).3.1.10 maximum run-out load or m
24、omentthe 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.3.1.11 mechanical deteriorationdeterioration that is vis-ible to the naked eye and is associated with
25、mechanical damageto the device under test (for example, initiation of fatigue crackor surface wear).3.1.12 offset angular displacement(distance OBFig. 6)offset on the angular displacement axis equal to 2 % of theintervertebral height, H, divided by the maximum radius of theimplant in the XY-plane; f
26、or 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 = 1.3.3.1.13 offset displacement(distance OBFig. 6) offset onthe linear displacement axis equal to 2 % of the intervertebralheig
27、ht (for example, 0.2 mm for a 10 mm intervertebralheight).3.1.14 permanent deformationthe remaining linear or an-gular displacement (axialmm, angulardegrees or radians)relative to the initial unloaded condition of the artificialintervertebral disc after the applied load or moment has beenremoved.3.1
28、.15 stiffness (axialn/mm, angularnmm/degree ornmm/radian)the slope of the initial linear portion of theload-displacement curve 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
29、 linear initial load/displacement curve, thedisplacement should be reported at 30 %, 60 %, and 90 % ofthe yield load or moment.3Nissan, M., Gilad, I., “The Cervical and Lumbar VertebraeAn Anthropomet-ric Model,” Engineering In Medicine, 13:3, 1984, pp. 111-114.4Lu, J., Ebraheim, N.A., Yang, H., Roll
30、ins, J., and Yeasting, R. A., “AnatomicBases forAnterior Spinal Surgery: SurgicalAnatomy of the Cervical Vertebral Bodyand Disc Space,” Surg Radiol Anat, 21:4, 1999, pp. 235-239.FIG. 1 Intervertebral Height DiagramF23460523.1.16 test blockthe component of the test apparatus formounting the artificia
31、l intervertebral disc in the intended testconfiguration.3.1.17 ultimate displacement (axialmm, angulardegrees or radians)the linear or angular displacement asso-ciated with the ultimate load or ultimate moment. This isillustrated as the displacement, OF, in Fig. 6.3.1.18 ultimate load or moment (axi
32、aln, 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 assembly. This is illustrated aspoint E in Fig. 6.3.1.19 yield displacementthe lin
33、ear 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 the distance OA in Fig. 6.3.1.20 yield load or momentthe applied load, F,ormoment,
34、 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 displacement. This isillustrated as point D in Fig. 6.4. Summary of Test Methods4.1 These
35、 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 safety factor for the levels indicated for implan-tation. If this worst-case size cann
36、ot 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 Fatigue testing of the artificial intervertebral discs willsimulate a motion segmen
37、t via a gap between two polyacetaltest blocks. The polyacetal will eliminate the effects of thevariability of bone properties and morphology for the fatiguetests. The minimum ultimate tensile strength of the polyacetalblocks shall be no less than 61 MPa.4.4 Static testing of the artificial intervert
38、ebral discs willsimulate a motion segment via a gap between two stainlessFIG. 2 Compression Testing ConfigurationF2346053steel blocks. The minimum tensile yield strength of the blocksshall be no less than 1170 MPa.4.5 The pushrod shall be manufactured from stainless steelhaving minimum tensile yield
39、 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 of these test methods must decidewhich series of tests are applicable to the artifici
40、al 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, the torsion test method may not apply to adevice that has no mechanical resistance
41、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 whileallowing motion at the operated level. These test methodsoutline materials and
42、 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 staticand dynamic characteristics of different designs of artificialintervertebral d
43、iscs. 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 standard model.5.3 The loads applied to the artificial intervertebral discsmay differ fro
44、m 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 inter-vertebral discs.5.4 Fatigue tests should be conducted in a 0.9 % salineenvironm
45、ental 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. Likewise, alternative testfrequencies may be used with adequate justification.5.5 It
46、is well known that the failure of materials is depen-dent upon stress, test frequency, surface treatments, and envi-ronmental factors. Therefore, when determining the effect ofchanging one of these parameters (for example, frequency,material, or environment), all others should be kept constant tofac
47、ilitate interpretation of the results. In particular, it may beFIG. 3 Compression/Shear Testing ConfigurationF2346054necessary to assess the influence of test frequency on devicefracture while holding the test environment, implant materialsand processing, and implant geometry constant.6. Apparatus6.
48、1 Test machines will conform to the requirements ofPractices E4.6.2 The intervertebral height, H, shall be determined fromvertebral body and disc morphometric data at the intendedlevel of application. Suggested heights are as follows: 4 mmfor the cervical spine, 6 mm for the thoracic spine, and 10 m
49、mfor the lumbar spine. The intervertebral height should not reachzero prior to the onset of functional failure deterioration. If thisoccurs, the test is considered a failure. The user of these testmethods should select the intervertebral height that is appro-priate for the device being tested.6.3 Axial Compression Test Apparatus:6.3.1 The actuator of the testing machine is connected to thepushrod by a minimal friction ball-and-socket joint or universaljoint (that is, unconstrained in bending). The pushrod isconnected to the superior fixture by a
