1、Designation: F2790 10 (Reapproved 2014)Standard Practice forStatic and Dynamic Characterization of Motion PreservingLumbar Total Facet Prostheses1This standard is issued under the fixed designation F2790; the number immediately following the designation indicates the year oforiginal adoption or, in
2、the case of revision, the year of last 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 This practice provides guidance for the static anddynamic testing of Lumbar Total Fa
3、cet Prostheses (FP). Theseimplants are intended to allow motion and lend support to oneor more functional spinal unit(s) through replacement of thenatural facets.1.2 These test methods are intended to provide a basis forthe mechanical comparison among past, present, and futurenon-biologic FP. These
4、test methods allow comparison ofdevices with different methods of application to the lumbarspine. These test methods are intended to enable the user tomechanically compare devices and do not purport to provideperformance standards for them.1.3 These test methods describe static and dynamic tests bys
5、pecifying load types and specific methods of applying theseloads.1.4 These test methods do not purport to address all clini-cally relevant failure modes for FP, some of which will bedevice specific. For example, these test methods do not addressimplant wear resistance under expected in vivo loads an
6、dmotions. In addition, the biologic response to wear debris is notaddressed in these test methods.1.5 Requirements are established for measuring displace-ments and evaluating the stiffness of FP.1.6 Some devices may not be testable in all test configura-tions.1.7 The values stated in SI units are to
7、 be regarded as thestandard with the exception of angular measurements, whichmay be reported in terms of either degrees or radians.1.8 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for in
8、formation onlyand are not considered standard.2. Referenced Documents2.1 ASTM Standards:2D638 Test Method for Tensile Properties of PlasticsE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE468 Practice for Presentation of Constant Amplit
9、ude Fa-tigue Test Results for Metallic MaterialsE739 Practice for StatisticalAnalysis of Linear or LinearizedStress-Life (S-N) and Strain-Life (-N) Fatigue DataF1582 Terminology Relating to Spinal Implants3. Terminology3.1 All functional and kinematic testing terminology isconsistent with the refere
10、nced standards (including Teminol-ogy E6 and Terminology F1582), unless otherwise stated.3.2 Definitions:3.2.1 coordinate systems/axesGlobal XYZ orthogonal axesare defined following a right-handed Cartesian coordinatesystem in which the XY plane is parallel to and co-planar withthe superior endplate
11、 of the inferior vertebral body. Alternativecoordinate systems may be used with justification. The globalaxes are fixed relative to the inferior vertebral body. Lowercase letters, xyz, denote a local moving orthogonal coordinatesystem attached to the superior vertebral body with directionsinitially
12、coincident with those of the global XYZ axes, respec-tively. The 3D motion of the superior relative to inferiorvertebra is specified and is to be measured in terms ofsequential Eulerian angular rotations about the xyz axes,respectively (z axial rotation, x lateral bend, and y flexion-extension).3.2.
13、1.1 origincenter of the global coordinate system thatis located at the posterior medial position on the superiorendplate of the inferior vertebral body.3.2.1.2 X-axispositive X-axis is to be directed anteriorlyrelative to the specimens initial unloaded position.3.2.1.3 Y-axispositive Y-axis is direc
14、ted laterally (towardthe left) relative to the specimens initial unloaded position.1This practice is under the jurisdiction ofASTM Committee F04 on Medical andSurgical Materials and Devices and is the direct responsibility of SubcommitteeF04.25 on Spinal Devices.Current edition approved Nov. 1, 2014
15、. Published November 2014. Originallyapproved in 2010. Last previous edition approved in 2010 as F2790-2010. DOI:10.1520/F279010R14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume inform
16、ation, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.1.4 Z-axispositive Z-axis is to be directed superiorlyrelative to the specimens initial unloaded position.3.2.2
17、 failurefunctional failure or substantial mechanicalfailure.3.2.2.1 functional failurepermanent deformation resultingfrom fracture, plastic deformation, or loosening beyond theultimate displacement or loosening that renders the spinalimplant assembly ineffective or unable to adequately resistload.3.
18、2.2.2 mechanical failurefailure associated with a defectin the material (for example, fatigue crack) or of the bondingbetween materials that may or may not produce functionalfailure.3.2.3 fatigue lifethe number of cycles, N, that the FP cansustain at a particular load or moment before failure occurs
19、.3.2.4 intended method of applicationa FP may containdifferent types of features to stabilize the implant-tissue inter-face such as threads, spikes, and textured surfaces. Each typeof feature has an intended method of application or attachmentto the spine.3.2.5 insertion point of an anchorthe locati
20、on where theanchor is attached to the test block. The insertion points shownin Fig. 1 are to be adhered to if possible. In situations where thedesign of the spinal implant assembly or the manufacturerssurgical instructions for installation dictate otherwise, theattachment points may deviate from the
21、se dimensions.3.2.6 longitudinal directionthe initial spatial orientationbetween the insertion points in the superior test blocks and theinferior test blocks.3.2.7 maximum run-out load or momentthe maximumload or moment for a given test that can be applied to a FPwhere all of the tested constructs h
22、ave withstood 10 000 000cycles without failure.3.2.8 mechanical deteriorationdeterioration that is visibleto the naked eye and is associated with mechanical damage tothe device under test (for example, initiation of fatigue crack orsurface wear).3.2.9 permanent deformationthe remaining linear or an-
23、gular displacement (axialmm, angulardegrees or radians)relative to the initial unloaded condition of the FP after theapplied load or moment has been removed.3.2.10 radius of rotationthe distance between the centerof rotation and the functional position (for example, load-bearing contact point) of th
24、e FP, for a given motion (that is,flexion/extension, lateral bending, or axial rotation).3.2.11 spinal implant assemblya complete spinal implantconfiguration as intended for surgical use. A spinal implantassembly may contain anchors, interconnections, and longitu-dinal elements and may contain trans
25、verse elements.3.2.12 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. 2. The device ma
26、ynot exhibit an isolated linear portion on the load/displacementcurve, due to the complicated nature of these devices. As such,these data are information only.FIG. 1 UHMWPE Test Block FIG. 2 Typical Load Displacement CurveF2790 10 (2014)23.2.13 superior/inferior spinal implant constructthe supe-rior
27、 or inferior spinal implant assembly attached to the testblock.3.2.14 test blockthe component of the test apparatus formounting the FP in the intended test configuration.3.2.15 tightening torquethe specified torque that is ap-plied to the various fasteners of the spinal implant assembly.3.2.16 torsi
28、onal ultimate load (Nm)the maximum torqueapplied to a spinal implant assembly (the torque at Point E inFig. 2). The ultimate torque should be a function of the deviceand not of the load cell or testing machine.3.2.17 total facet prosthesisnonbiologic structure in-tended to restore the support and mo
29、tion of the vertebral facetjoint.3.2.18 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,inFig. 2.3.2.19 ultimate load or moment (axialN, angularNmm)the maxim
30、um applied load, F, or moment, M, transmitted tothe FP. This is illustrated as point E in Fig. 2.3.2.20 zero displacement intercept (mm)the intersectionof the straight line section of the load displacement curve andzero load axis (the zero displacement reference Point O in Fig.2).4. Summary of Pract
31、ice4.1 This practice is proposed for the mechanical testing ofFP.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 cannot be determined usingtheoretical or experimental methods such as simple st
32、resscalculations or finite element analysis, then all available sizesor a justified selection are to be tested and the complete rangeof results are to be reported.4.3 Static and dynamic testing of the devices will simulate amotion segment via a gap between two Ultra High MolecularWeight Polyethylene
33、 (UHMWPE) test blocks (Fig. 1, Fig. 3,orFig. 4). The UHMWPE used to manufacture the test blocksshould have a tensile breaking strength equal to 40 6 3 MPa(see Specification D638). The UHMWPE will eliminate theeffects of the variability of bone properties and morphology forthe fatigue tests.4.4 Stati
34、c and dynamic tests will evaluate the devices. Theuser of this practice must decide which series of tests areapplicable to the device in question. The user of this practicemay choose to use all or a selection of the tests described fortesting a particular device.4.5 This practice is intended to be a
35、pplicable to FP thatsupport and transmit motion by means of an articulating jointor by use of compliant materials and/or design. Ceramics,metals, and/or polymers may be used in FP design, and it is thegoal of this practice to enable a comparison of these devices,regardless of material and type of de
36、vice.5. Significance and Use5.1 Facet Prosthesis ComponentsThe facet replacementmay comprise a variety of shapes and configurations. Its formsNOTE 1(A) Anterior-Posterior, (B) Superior-Inferior, (C) Medial-Lateral setups are shown. These setups require one translational actuator and mayrequire speci
37、fic fixturing. Test blocks are shown in grey. The arrow indicates the loading direction.FIG. 3 Diagrams of Possible Test Setups for Translational Loading of a FPF2790 10 (2014)3may include, but are not limited to, ball and socket articulatingjoints, joints having a free-floating or semi-constrained
38、thirdbody, metallic load-bearing surfaces, and spring and dampen-ing mechanisms.Additionally, it may be a unilateral or bilateraldesign.5.2 These test methods are designed to quantify the staticand dynamic characteristics of different designs of FP. The testsare conducted in vitro in order to allow
39、for analysis ofindividual devices and comparison of the mechanical perfor-mance of multiple designs.5.3 The loads applied to the FP may differ from the complexloading seen in vivo, and therefore, the results from these testsmay not directly predict in vivo performance. The results,however, can be us
40、ed to compare mechanical performance indifferent devices.5.4 Fatigue testing in a simulated body fluid or saline maycause fretting, corrosion, or lubricate the interconnections andthereby affect the relative performance of tested devices. Thistest should be conducted in a 0.9 % saline environmental
41、bathat 37C at a maximum rate of 10 Hz for all metallic devices and2 Hz for non-metallic devices. Other test environments such asa simulated body fluid, a saline drip or mist, distilled water,other type of lubrication or dry could also be used withadequate justification. Likewise, alternative test fr
42、equenciesmay be used with adequate justification to ensure that it doesnot impact the device performance.5.5 It is well known that the failure of materials is depen-dent upon stress, test frequency, surface treatments, and envi-ronmental factors. Therefore, when determining the effect ofchanging the
43、se parameters (for example, frequency, material,or environment), care should be taken to allow for appropriateinterpretation of the results. In particular, it may be necessaryto assess the influence of test frequency on device fracturewhile holding the test environment, implant materials andprocessi
44、ng, and implant geometry constant.6. Apparatus and Setup6.1 Test machines will conform to the requirements ofPractices E4.6.2 The test apparatus will allow multiple loading regimesto be applied to all forms of FP.6.3 The test block should be created according to Fig. 1.Variations from this design to
45、 accommodate a devices fixationmethod or features should be reported and justified.6.4 The interpedicular spacing (superior-to-inferior center-to-center distance between bone anchors) shall be set at 38 mmwhen installing the device and at the beginning of each test.The implants should be placed in t
46、he UHMWPE blocksaccording to the recommended surgical technique. For devicesthat do not require pedicular fixation appropriate test blocksshould be manufactured to ensure proper evaluation of thefixation components.6.5 Install the FP in the UHMWPE blocks according to themanufacturers instructions. I
47、f necessary, utilize an aluminumspacer block between the superior and inferior UHMWPEblocks to fix them with respect to each other during installationNOTE 1(A) Simulated Flexion-Extension, (B) Axial Rotation, (C) Lateral Bending setups are shown. These setups require one rotational actuator andmay r
48、equire specific fixturing. The arrow indicates the rotation direction. Test blocks are shown in grey. The position of the axis of rotation should bebased on the information in Table X1.1.FIG. 4 Diagrams of Possible Test Setups for Rotational Loading of a FPF2790 10 (2014)4and remove after installati
49、on is complete. The spacer blockshould ensure that the device is installed with the proper activelongitudinal length.6.6 The motion of the superior test construct relative to theinferior test construct shall be constrained in three-dimensionalspace except for the components in the direction of specifiedtest motions/loads.6.7 Translational Test Option Setup:6.7.1 The linear actuator of the test frame is connected to thesuperior test block so that its axis is collinear with the testdirection (Fig. 3).6.7.2 The inferior test block sho
