1、Designation: F 2077 03Test Methods ForIntervertebral Body Fusion Devices1This standard is issued under the fixed designation F 2077; 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
2、 indicates the year of last reapproval. Asuperscript epsilon (e) 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 designe
3、d to 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 devic
4、eassemblies 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
5、fusiondevice assemblies.1.3 The test method describes static and dynamic tests byspecifying load types and specific methods of applying theseloads. These tests are designed to allow for the comparativeevaluation of intervertebral body fusion device assemblies.1.4 This test method does not address ex
6、pulsion testing ofintervertebral body fusion device assemblies (see X1.11).1.5 Guidelines are established for measuring displacements,determining the yield load or moment, evaluating the stiffness,and strength of the intervertebral body fusion device assem-blies.1.6 Some intervertebral body fusion d
7、evice assemblies maynot be testable in all test configurations.1.7 The values stated in SI units are to be regarded as thestandard with the 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 con
8、cerns, if any, associated with 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:E 4 Practices for Force Verification of
9、 Testing Machines2E 6 Terminology Relating to Methods of Mechanical Test-ing2E 1823 Terminology Relating to Fatigue and Fracture Test-ing2F 1582 Terminology Relating to Spinal Implants33. Terminology3.1 For definition of terms refer to Terminology E 6,E 1823, and F 1582.3.2 Definitions of Terms Spec
10、ific to This Standard:3.2.1 coordinate system/axes, nThree orthogonal axes aredefined by Terminology F 1582. The center of the coordinatesystem is located at the geometric center of the intervertebralbody fusion device assembly. The XY plane is to bisect thesagittal plane angle between superior and
11、inferior lines (sur-faces) that are intended to simulate the adjacent vertebral endplates. The positive Z axis is to be directed superiorly. Forcecomponents parallel to the XY plane are shear components ofloading. The compressive axial force is defined to be thecomponent in the negative Z direction.
12、 Torsional load isdefined to be the component of moment parallel to the Z axis.3.2.2 fatigue life, nThe number of cycles, N, that theintervertebral body fusion device assembly can sustain at aparticular load or moment before mechanical or functionalfailure occurs.3.2.3 functional failure, nPermanent
13、 deformation thatrenders the intervertebral body fusion device assembly inef-fective or unable to resist load and/or maintain attachmentadequately.3.2.4 ideal insertion location, nThe implant location withrespect to the simulated inferior and superior vertebral bodies(polyacetal or metal blocks) dic
14、tated by the type, design, andmanufacturers surgical installation instructions.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 on Spinal Devices.Current edition approved Apr. 10, 200
15、3. Published May 2003. Originallypublished in 2000. Last previous edition approved in 2001 as F 2077 - 01.2Annual Book of ASTM Standards, Vol 03.01.3Annual Book of ASTM Standards, Vol 13.01.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United St
16、ates.3.2.5 intended method of application, nIntervertebralbody fusion device assemblies may contain different types ofstabilizing anchors such as threads, spikes, and knurled sur-faces. Each type of anchor has an intended method of appli-cation or attachment to the spine.3.2.6 intended spinal locati
17、on, nThe anatomic region ofthe spine intended for the intervertebral body fusion deviceassembly. Intervertebral body fusion device assemblies may bedesigned and developed for specific regions of the spine suchas the lumbar, thoracic, and cervical spine. Also, there existsdifferent anatomical potenti
18、al surgical approaches, which willresult in different implant orientation at different levels of thespine.3.2.7 intervertebral body fusion device, nA structure (bio-logic or synthetic) that is placed in the disc space between twoadjacent vertebral bodies to provide support for eventualarthrodesis of
19、 the two adjacent vertebral bodies.3.2.8 intradiscal height, nThe straight-line distance alongthe Z axis between the unaltered simulated vertebral bodiesminimum height of 4 mm and a maximum height of 18 mm.See Fig. 1.3.2.9 load point, nThe point through which the resultantforce on the intervertebral
20、 device passes (that is, the geometriccenter of the superior fixtures sphere) (Figs. 2-5).3.2.10 maximum run out load or moment, nThe maxi-mum load or 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
21、 000 cycles withoutfunctional or mechanical failure.3.2.11 mechanical failure, nThat associated with the on-set of a defect in the material (that is, initiation of fatigue crackor surface wear).3.2.12 offset angular displacement, n(Distance OBFig.6)Offset on the angular displacement axis equal to 10
22、 % ofthe intradiscal height, H, divided by the outside diameter orheight of the implant (maximum dimension of implant in XZplane if not cylindrical) (for example, for a 10-mm intradiscalheight and 16-mm intervertebral body fusion device assembly,distance OB = 10 mm/16 mm (0.10)(180)/p = 3.6).3.2.13
23、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).3.2.14 permanent deformation, nThe remaining displace-ment (mm or degrees or radians) relative to the initial unloadedcondition of the inter
24、vertebral body fusion device assemblyafter the applied load has been removed.3.2.15 stiffness (N/mm or N*mm/Degree (Radian) (TheSlope of Line OGFig. 6), nThe slope of the initial linearportion of the load-displacement curve or the slope of theinitial linear portion of the momentangular displacementc
25、urve.3.2.16 test block, nThe component of the test apparatusfor mounting the intervertebral body fusion device assemblyfor the intended test configuration.3.2.17 ultimate displacement (millimetres or degrees orradians) (Displacement OFFig. 6), nThe displacementassociated with the ultimate load or ul
26、timate moment.3.2.18 ultimate load or moment (N or N*mm) (PointEFig. 6), nThe maximum applied load, F, transmitted bythe pushrod (assumed equal to force component parallel to andindicated by load cell), or the applied moment about the Z axisthat can be applied to an intervertebral body fusion device
27、assembly.3.2.19 yield displacement (Distance OAFig. 6), nThedisplacement (mm) or angular displacement (deg) when aninterbody fusion device asembly has a permanent deformationequal to the offset displacement or the offset angular displace-ment.3.2.20 yield load or moment (Point DFig. 6), nTheapplied
28、load, F, transmitted by the pushrod (assumed equal toforce component parallel to and indicated by load cell), or theapplied moment about the Z axis required to produce apermanent deformation equal to the offset displacement or theoffset angular displacement.4. Summary of Test Method4.1 These test me
29、thods are proposed for the mechanicaltesting 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 poly
30、acetal will eliminate theeffects 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
31、via a gap betweenFIG. 1 Intradiscal Height DiagramF2077032two stainless steel blocks. The minimum ultimate tensilestrength of the blocks shall be no less than 1310 MPa.4.4 The pushrod shall also be manufactured from stainlesssteel, which shall also have a minimum ultimate tensilestrength no less tha
32、n 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 question. The user of this testmethod may choose to use all or a selec
33、tion of the testsFIG. 2 Compression Testing ConfigurationFIG. 3 Compression-Shear Testing ConfigurationF2077033described 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 sim
34、ple geometric-shaped devices 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 o
35、f different intervertebral body 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
36、to allow for analysis and comparison of the mechanicalFIG. 4 Torsion Testing Configuration With Pin-Slot GimbalFIG. 5 Spherical Gimbal (Cross Section) for Torsion Testing ApparatusF2077034performance of intervertebral body fusion device assemblies tospecific load modalities.5.3 The loads applied to
37、the intervertebral body fusionassemblies may differ from the complex loading seen in vivo,and therefore, the results from these tests may not directlypredict in vivo performance. The results, however, can be usedto compare mechanical performance of different intervertebralbody fusion device assembli
38、es.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 considered.Fatigue tests should first be conducted in air (at ambienttemperature) for comparison purposes since the environmentaleffects c
39、ould be significant. If a simulated in vivo environmentis desired, the investigator should consider testing in a salineenvironmental bath at 37C (for example, 0.9-g NaCl per100-mL water) at a rate of 1 Hz or less. A simulated body fluid,a saline drip or mist, distilled water, or other type of lubric
40、ationat 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 in physiologicsolution as described in 5.4. Devices that require physiologicsolution for testing should be tested in the same type solutio
41、nfor comparison purposes.5.6 The location within the simulated vertebral bodies andposition of the intervertebral body fusion device assembly withrespect to the loading axis will be dependent upon the design,the manufacturers recommendation, or the surgeons preferredmethod for implant placement.5.7
42、It 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 must be kept constant tofa
43、cilitate interpretation of the results.6. Apparatus6.1 Test machines will conform to the requirements ofPractices E 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 l
44、umbar spine, 6 mm for the thoracic spine, and 4 mm forthe cervical spine. The intradiscal height should not reach zerobefore 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 appropr
45、iatefor the device being tested.6.3 Axial Compression Test ApparatusThe actuator of thetesting machine is connected 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 s
46、phere joint (that is,unconstrained in bending and torsion). The hollow pushrodFIG. 6 Typical Load Displacement CurveF2077035should be of minimal weight so as to be considered a“two-force” member. It thus applies to the intervertebral bodyfusion device assembly a resultant force directed along thepus
47、hrods axes and located at the center of the superiorfixtures sphere joint (the geometric center of the device beingtested). 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 u
48、sed,which could be incorporated as an integral part of the superiorand inferior fixtures. The blocks are to have surfaces that mategeometrically with the intervertebral device similar to how thedevice is intended to mate with vertebral end plates. The testapparatus will be assembled such that the Z
49、axis of theintervertebral device is initially coincident with the pushrodsaxis and collinear with the axis of the testing machinesactuator and load cell. The length of the pushrod between thecenter of the ball-and-socket joint to the center of the sphericalsurface is to be a minimum of 38 cm. This is required tominimize deviation of the pushrods axis (direction of appliedforce, F) from that of the test machines load cell axis. In otherwords, this is to minimize the error in using and reporting thatthe force indicated by the load cell “Find
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