1、Designation: F2077 14Test Methods ForIntervertebral Body Fusion Devices1This standard is issued under the fixed designation F2077; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses i
2、ndicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the materials and methods forthe static and dynamic testing of intervertebral body fusiondevice assemblies, spinal implants designed t
3、o promote arthro-desis at a given spinal motion segment.1.2 This test method is intended to provide a basis for themechanical comparison among past, present, and future non-biologic intervertebral body fusion device assemblies. This testmethod allows comparison of intervertebral body fusion deviceas
4、semblies with different intended spinal locations and meth-ods of application to the intradiscal spaces. This test method isintended to enable the user to compare intervertebral bodyfusion device assemblies mechanically and does not purport toprovide performance standards for intervertebral body fus
5、iondevice assemblies.1.3 The test method describes static and dynamic tests byspecifying force types and specific methods of applying theseforces. These tests are designed to allow for the comparativeevaluation of intervertebral body fusion device assemblies.1.4 These tests are designed to character
6、ize the structuralintegrity of the device and are not intended to test thebone-implant interface.1.5 This test method does not address expulsion testing ofintervertebral body fusion device assemblies (see 1.4).1.6 Guidelines are established for measuring displacements,determining the yield force or
7、moment, evaluating the stiffness,and strength of the intervertebral body fusion device assem-blies.1.7 Some intervertebral body fusion device assemblies maynot be testable in all test configurations.1.8 The values stated in SI units are to be regarded asstandard. No other units of measurement are in
8、cluded in thisstandard, with the exception of angular measurements, whichmay be reported in terms of either degrees or radians.1.9 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 a
9、ppro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE177 Practice for Use of the Terms
10、 Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1823 Terminology Relating to Fatigue and Fracture TestingE2309 Practices for Verification of Displacement MeasuringSystems and Devices Used in Material Testing Mach
11、inesF1582 Terminology Relating to Spinal Implants3. Terminology3.1 For definition of terms refer to Terminology E6, E1823,and F1582.3.2 Definitions of Terms Specific to This Standard:3.2.1 coordinate system/axes, nThree orthogonal axes aredefined by Terminology F1582. The center of the coordinatesys
12、tem is located at the geometric center of the intervertebralbody fusion device assembly. The XY plane is to bisect thesagittal plane angle between superior and inferior lines (sur-faces) that are intended to simulate the adjacent vertebral endplates. The positive Z axis is to be directed superiorly.
13、 Forcecomponents parallel to the XY plane are shear components ofloading. The compressive axial force is defined to be thecomponent in the negative Z direction. Torsional force isdefined to be the component of moment parallel to the Z axis.3.2.2 crack, nan externally visible physical discontinuityin
14、 the form of a narrow opening that arises from mechanicalforces.1This test method is under the jurisdiction of ASTM Committee F04 on Medicaland Surgical Materials and Devices and is the direct responsibility of SubcommitteeF04.25 .Current edition approved Oct. 1, 2014. Published December 2014. Origi
15、nallypublished in 2000. Last previous edition approved in 2011 as F2077 - 11 DOI:10.1520/F2077-14.2For 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 Docu
16、ment Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.3 fatigue life, nthe number of cycles, N, that theintervertebral body fusion device assembly can sustain at aparticular force or moment before me
17、chanical or functionalfailure occurs.3.2.4 functional failure, npermanent deformation that ren-ders the intervertebral body fusion device assembly ineffectiveor unable to resist force and/or maintain attachment adequately.3.2.5 ideal insertion location, nthe implant location withrespect to the simul
18、ated inferior and superior vertebral bodies(polyacetal or metal blocks) dictated by the type, design, andmanufacturers surgical installation instructions.3.2.6 intended method of application, nintervertebralbody fusion device assemblies may contain different types ofstabilizing anchors such as threa
19、ds, spikes, and knurled sur-faces. Each type of anchor has an intended method of appli-cation or attachment to the spine.3.2.7 intended spinal location, nthe anatomic region ofthe spine intended for the intervertebral body fusion deviceassembly. Intervertebral body fusion device assemblies may bedes
20、igned and developed for specific regions of the spine suchas the lumbar, thoracic, and cervical spine. Also, there existsdifferent anatomical potential surgical approaches, which willresult in different implant orientation at different levels of thespine.3.2.8 intervertebral body fusion device, na s
21、tructure (bio-logic or synthetic) that is placed in the disc space between twoadjacent vertebral bodies to provide support for eventualarthrodesis of the two adjacent vertebral bodies.3.2.9 intradiscal height, nthe straight-line distance alongthe Z axis between the unaltered simulated vertebral bodi
22、esminimum height of 4 mm and a maximum height of 18 mm.See Fig. 1.3.2.10 force point, nthe point through which the resultantforce on the intervertebral device passes (that is, the geometriccenter of the superior fixtures sphere) (Figs. 2-5).3.2.11 maximum run out force or moment, nthe maximumforce o
23、r moment for a given test that can be applied to anintervertebral body fusion device assembly in which all of thetested constructs have withstood 5 000 000 cycles withoutfunctional or mechanical failure.3.2.12 mechanical failure, nthat associated with the onsetof a new defect in the material (that i
24、s, initiation of fatiguecrack).3.2.13 offset angular displacement, n(Distance OBFig.6)offset on the angular displacement axis equal to 10 % ofthe intradiscal height, H, divided by the outside diameter orheight of the implant (maximum dimension of implant in XZplane if not cylindrical) (for example,
25、for a 10-mm intradiscalheight and 16-mm intervertebral body fusion device assembly,distance OB = 10 mm/16 mm (0.10)(180)/ = 3.6).3.2.14 offset displacement, n(Distance OBFig. 6)offset on the displacement axis equal to 2 % of the intradiscalheight (that is, 0.2 mm for a 10-mm intradiscal height).3.2.
26、15 permanent deformation, nthe remaining displace-ment (mm or degrees or radians) relative to the initial unloadedcondition of the intervertebral body fusion device assemblyafter the applied force has been removed.3.2.16 stiffness (N/mm or N*mm/Degree (Radian) (TheSlope of Line OGFig. 6), nthe slope
27、 of the initial linearportion of the force-displacement curve or the slope of theinitial linear portion of the momentangular displacementcurve.3.2.17 test block, nthe component of the test apparatus formounting the intervertebral body fusion device assembly forthe intended test configuration.3.2.18
28、ultimate displacement (mm or degrees or radians)(Displacement OFFig. 6), nthe displacement associatedwith the ultimate force or ultimate moment.3.2.19 ultimate force or moment (N or N*mm) (PointEFig. 6), nthe maximum applied force, F, transmitted bythe pushrod (assumed equal to force component paral
29、lel to andindicated by load cell), or the applied moment about the Z axisthat can be applied to an intervertebral body fusion deviceassembly.3.2.20 yield displacement (Distance OAFig. 6), nthedisplacement (mm) or angular displacement (deg) when aninterbody fusion device asembly has a permanent defor
30、mationequal to the offset displacement or the offset angular displace-ment.FIG. 1 Intradiscal Height DiagramF2077 1423.2.21 yield force or moment (Point DFig. 6), ntheapplied force, F, transmitted by the pushrod (assumed equal toforce component parallel to and indicated by load cell), or theapplied
31、moment about the Z axis required to produce apermanent deformation equal to the offset displacement or theoffset angular displacement.FIG. 2 Compression Testing ConfigurationFIG. 3 Compression-Shear Testing ConfigurationF2077 1434. Summary of Test Method4.1 These test methods are proposed for the me
32、chanicaltesting of intervertebral body fusion device assemblies specificto the lumbar, thoracic, and cervical spine.4.2 Fatigue testing of the intervertebral body fusion deviceassemblies will simulate a motion segment via a gap betweentwo polyacetal test blocks. The polyacetal will eliminate theeffe
33、cts of the variability of bone properties and morphology forthe fatigue tests. The minimum ultimate tensile strength of thepolyacetal blocks shall be no less than 61 MPa.4.3 Static testing of the intervertebral body fusion deviceassemblies will simulate a motion segment via a gap betweentwo stainles
34、s steel blocks. The minimum ultimate tensilestrength of the blocks shall be no less than 1310 MPa.FIG. 4 Torsion Testing Configuration With Pin-Slot GimbalFIG. 5 Spherical Gimbal (Cross Section) for Torsion Testing ApparatusF2077 1444.4 The pushrod shall also be manufactured from stainlesssteel, whi
35、ch shall also have a minimum ultimate tensilestrength no less than 1310 MPa.4.5 Static and dynamic tests will evaluate the intervertebralbody fusion device assembly. The user of this test method mustdecide which series of tests are applicable to the intervertebralbody fusion device assembly in quest
36、ion. The user of this testmethod may choose to use all or a selection of the testsdescribed in this test method for testing a particular interver-tebral body fusion device assembly.5. Significance and Use5.1 Intervertebral body fusion device assemblies are gener-ally simple geometric-shaped devices
37、which are often porousor hollow in nature. Their function is to support the anteriorcolumn of the spine to facilitate arthrodesis of the motionsegment. This test method outlines materials and methods forthe characterization and evaluation of the mechanical perfor-mance of different intervertebral bo
38、dy fusion device assembliesso that comparisons can be made between different designs.5.2 This test method is designed to quantify the static anddynamic characteristics of different designs of intervertebralbody fusion device assemblies. These tests are conducted invitro to allow for analysis and com
39、parison of the mechanicalperformance of intervertebral body fusion device assemblies tospecific force modalities.5.3 The forces applied to the intervertebral body fusionassemblies may differ from the complex loading seen in vivo,and therefore, the results from these tests may not directlypredict in
40、vivo performance. The results, however, can be usedto compare mechanical performance of different intervertebralbody fusion device assemblies.5.4 Since the environment may affect the dynamic perfor-mance of intervertebral body fusion device assemblies, dy-namic testing in a saline environment may be
41、 considered.Fatigue tests should first be conducted in air (at ambienttemperature) for comparison purposes since the environmentaleffects could be significant. If a simulated in vivo environmentis desired, the investigator should consider testing in a salineenvironmental bath at 37C (for example, 0.
42、9-g NaCl per100-mL water) at a rate of 1 Hz or less.Asimulated body fluid,a saline drip or mist, distilled water, or other type of lubricationat 37C could also be used with adequate justification.5.5 If the devices are known to be temperature and envi-ronment dependent, testing should be conducted i
43、n physiologicsolution as described in 5.4. Devices that require physiologicsolution for testing should be tested in the same type solutionfor comparison purposes.5.6 The location within the simulated vertebral bodies andposition of the intervertebral body fusion device assembly withrespect to the lo
44、ading axis will be dependent upon the design,FIG. 6 Typical Force Displacement CurveF2077 145the manufacturers recommendation, or the surgeons preferredmethod for implant placement.5.7 It is well known that the failure of materials is depen-dent upon stress, test frequency, surface treatments, and e
45、nvi-ronmental factors. Therefore, when determining the effect ofchanging one of these parameters (for example, frequency,material, or environment), all others must be kept constant tofacilitate interpretation of the results.6. Apparatus6.1 Test machines will conform to the requirements ofPractices E
46、4.6.2 The intradiscal height, H, shall be determined fromvertebral body and disc morphometric data at the intendedlevel of application. Suggested heights are as follows: 10 mmfor the lumbar spine, 6 mm for the thoracic spine, and 4 mm forthe cervical spine. The intradiscal height should not reach ze
47、robefore the onset of functional or mechanical failure. If thisoccurs, the test is considered a failure. The user of the testmethod should select the intradiscal height that is appropriatefor the device being tested.6.3 Axial Compression Test ApparatusThe actuator of thetesting machine is connected
48、to the pushrod by a minimalfriction ball and socket joint or universal joint (that is,unconstrained in bending). The pushrod is connected to thesuperior fixture by a minimal friction sphere joint (that is,unconstrained in bending and torsion). The hollow pushrodshould be of minimal weight so as to b
49、e considered a“two-force” member. It thus applies to the intervertebral bodyfusion device assembly a resultant force directed along thepushrods axis and located at the center of the superior fixturessphere joint (the geometric center of the device being tested).For the fatigue tests, the device is placed between twopolyacetal blocks, which are rigidly attached to the metalblocks (Fig. 2). For the static tests, metal blocks are to be used,which could be incorporated as an integral part of the superiorand inferior fixtures. The blocks a
