1、Designation: F1717 11Standard Test Methods forSpinal Implant Constructs in a Vertebrectomy Model1This standard is issued under the fixed designation F1717; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、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 cover the materials and methods forthe static and fatigue testing of spinal implant assemblies in avertebrectomy m
3、odel.The test materials for most combinationsof spinal implant components can be specific, depending on theintended spinal location and intended method of application tothe spine.1.2 These test methods are intended to provide a basis forthe mechanical comparison among past, present, and futurespinal
4、 implant assemblies. They allow comparison of spinalimplant constructs with different intended spinal locations andmethods of application to the spine. These test methods are notintended to define levels of performance, since sufficientknowledge is not available to predict the consequences of theuse
5、 of a particular device.1.3 These test methods set out guidelines for load types andmethods of applying loads. Methods for three static load typesand one fatigue test are defined for the comparative evaluationof spinal implant assemblies.1.4 These test methods establish guidelines for measuringdispl
6、acements, determining the yield load, and evaluating thestiffness and strength of the spinal implant assembly.1.5 Some spinal constructs may not be testable in all testconfigurations.1.6 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisst
7、andard.1.7 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 and health practices and determine the applica-bility of regulatory limitations prior to use.2. Refer
8、enced Documents2.1 ASTM Standards:2D638 Test Method for Tensile Properties of PlasticsE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of MechanicalTestingE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an
9、 Interlaboratory Study toDetermine the Precision of a Test MethodE739 Practice for Statistical Analysis of Linear or Linear-ized Stress-Life (S-N) and Strain-Life (e-N) Fatigue DataE1150 Definitions of Terms Relating to FatigueF1582 Terminology Relating to Spinal ImplantsF2077 Test Methods For Inter
10、vertebral Body Fusion De-vices3. Terminology3.1 Definitions:3.1.1 For definitions of terms relating to these test methods,see Terminology E6, Terminology F1582, and DefinitionsE1150.3.2 Definitions of Terms Specific to This Standard:3.2.1 active length of the longitudinal elementthe straightline dis
11、tance between the center of attachment of the superioranchor and the center of attachment of the inferior anchor.3.2.2 angular displacement at 2 % offset yield (degrees)the angular displacement of a construct measured via theactuator that produces a permanent angular displacement in theX-Y plane equ
12、al to 0.020 times the torsional aspect ratio (seePoint A in Fig. 1).3.2.3 block moment armthe perpendicular to the appliedload between the insertion point of an anchor and the axis ofthe hinge pin.1These test methods are under the jurisdiction of ASTM Committee F04 onMedical and Surgical Materials a
13、nd Devices and are the direct responsibility ofSubcommittee F04.25 on Spinal Devices.Current edition approved June 1, 2011. Published June 2011. Originallyapproved in 1996. Last previous edition approved in 2010 as F1717 10. DOI:10.1520/F1717-11.2For referenced ASTM standards, visit the ASTM website
14、, 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 website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
15、3.2.4 compressive or tensile bending stiffness (N/mm)thecompressive or tensile bending yield force divided by elasticdisplacement (see the initial slope of line BC in Fig. 1).3.2.5 compressive or tensile bending ultimate load (N)themaximum compressive or tensile force in the X-Z plane appliedto a sp
16、inal implant assembly (see the force at Point E in Fig. 1).The ultimate load should be a function of the device and not ofthe load cell or testing machine.3.2.6 compressive or tensile bending yield load (N)thecompressive or tensile bending force in the X-Z plane neces-sary to produce a permanent def
17、ormation equal to 0.020 timesthe active length of the longitudinal element (see the force atPoint D in Fig. 1).3.2.7 coordinate system/axesthree orthogonal axes aredefined in Fig. 2 and Fig. 3. The anterior-posterior axis is Xwith positive being anterior. The medial-lateral axis is Y withleft being
18、positive when viewed posteriorly. The superior-inferior axis is Z with superior being positive.3.2.8 displacement at 2 % offset yield (mm)the displace-ment of a construct measured via the actuator that produces apermanent deformation equal to 0.020 times the active lengthof the longitudinal element
19、(see Point A in Fig. 1).3.2.9 elastic angular displacement (degrees)the angulardisplacement at 2 % offset yield (see Point A in Fig. 1) minusthe 2 % offset angular displacement (see Point B in Fig. 1).(The distance between Point A and Point B in Fig. 1.)3.2.10 elastic displacement (mm)the displaceme
20、nt at 2 %offset yield (see Point A in Fig. 1) minus the 2 % offsetdisplacement (see Point B in Fig. 1). (The distance betweenPoint A and Point B in Fig. 1.)FIG. 1 Typical Load Displacement Curve or Torque AngulationCurveFIG. 2 A Standard Bilateral Construct Containing Screw, Rod andScrewFIG. 3 A Bil
21、ateral Hook, Rod, Screw, and Transverse ElementConstructF1717 1123.2.11 failurepermanent deformation resulting from frac-ture, plastic deformation, or loosening beyond the ultimatedisplacement or loosening that renders the spinal implantassembly ineffective or unable to adequately resist load.3.2.12
22、 fatigue lifethe number of loading cycles, N,ofaspecified character that the spinal implant assembly sustainsbefore failure of a specified nature occurs (see DefinitionsE1150).3.2.13 insertion point of an anchorthe location where theanchor is attached to the test block. The insertion points shownin
23、Figs. 2-15 are to be adhered to if possible. In situationswhere the design of the spinal implant assembly or themanufacturers surgical instructions for installation dictateotherwise, the attachment points may deviate from thesedimensions.3.2.14 intended method of applicationspinal implant as-semblie
24、s contain different types of anchors. Each type ofanchor has an intended method of application to the spine.3.2.15 intended spinal locationthe anatomic region of thespine intended for the application of the spinal implantassembly. Spinal implant assemblies are developed for specificspinal locations
25、such as the anterior cervical spine or theposterior thoracolumbar, lumbar, and lumbosacral spine.3.2.16 hinge pinthe cylindrical rod connecting a testblock to a side support. A cervical construct is secured with a9.6 mm diameter pin and the thoracolumbar, lumbar, andlumbosacral construct uses a 12.7
26、 mm diameter pin.3.2.17 longitudinal directionthe initial spatial orientationparallel to the longitudinal element of the spinal implantassembly. The longitudinal direction is generally in thesuperior-inferior direction and, therefore, generally parallel tothe z axis.3.2.18 maximum run-out loadthe ma
27、ximum load that canbe applied to a spinal implant assembly where all of the testedconstructs have withstood 5 000 000 cycles without a failure.3.2.19 permanent deformationthe displacement (mm) orangular displacement (degree) of the spinal implant constructrelative to the initial unloaded condition a
28、s measured via theactuator after the applied load, moment, or torque has beenremoved.3.2.20 spinal implant assemblya complete spinal implantconfiguration as intended for surgical use. A spinal implantassembly will contain anchors, interconnections, and longitu-dinal elements and may contain transver
29、se elements (see Fig. 4,Fig. 6, Fig. 8, Fig. 10, Fig. 12, and Fig. 14).3.2.21 spinal implant constructa complete spinal implantassembly attached to the appropriate test blocks.3.2.22 test blockthe component of the test apparatus formounting the spinal implant assembly.Aspecific design of testblock i
30、s required for each intended spinal location and intendedFIG. 4 Cervical Unilateral Construct Test Setup for Screws or BoltsF1717 113method of application. Fig. 5, Fig. 7, Fig. 9, Fig. 11, Fig. 13,and Fig. 15 describe the recommended designs for the testblocks; however, alternate designs can be used
31、 as long asequivalent performance is demonstrated.3.2.23 test block load pointthe location on the test blockat which the resultant load is transmitted from the testapparatus.3.2.24 tightening torquethe specified torque that is ap-plied to the various threaded fasteners of the spinal implantassembly.
32、3.2.25 torsional aspect ratiothe active length of thelongitudinal element divided by the distance from the center ofrotation to the insertion point of an anchor (for example: in Fig.2 1.70 for a 76-mm active length, X =40mmandY = 40/2mm).A 5LD5Lx21 y2!1/2(1)FIG. 5 Cervical Unilateral UHWMPE Block fo
33、r Screws or BoltsF1717 114where:A = torsional aspect ratio,L = active length of longitudinal element,D = distance to insertion point,x = x distance to insertion point, andy = y distance to insertion point.3.2.26 torsional stiffness (N-m/degree)the yield torque(N-m) divided by elastic angular displac
34、ement (degrees) (theinitial slope of line BC in Fig. 1).3.2.27 torsional ultimate load (N-m)the maximum torquein the X-Y plane applied to a spinal implant assembly (thetorque at Point E in Fig. 1). The ultimate torque should be afunction of the device and not of the load cell or testingmachine.3.2.2
35、8 two percent (2 %) offset angular displacement(degrees)a permanent angular displacement in the X-Y planemeasured via the actuator equal to 0.020 times the torsionalaspect ratio (for example: 1.95 for 1.70 3 0.02 3 180/pi)(see Point B in Fig. 1).3.2.29 two percent (2 %) offset displacement (mm)a per
36、-manent deformation measured via the actuator equal to 0.020times the active length of the longitudinal element (for ex-ample: 1.52 mm for a 76 mm active length of the longitudinalelement or 0.70 mm for 35 mm) (see Point B in Fig. 1).3.2.30 ultimate displacement (mm)the displacement asso-ciated with
37、 the ultimate load, ultimate bending load or ultimatetorque (the displacement at Point F in Fig. 1).3.2.31 yield torque (N-m)the torque in the X-Y planerequired to produce a permanent displacement of 0.020 timesthe torsional aspect ratio (the torque at Point D in Fig. 1).3.2.32 zero displacement int
38、ercept (mm)the intersectionof the straight line section of the load displacement curve andthe zero load axis (the zero displacement reference Point 0 inFig. 1).4. Summary of Test Methods4.1 Similar test methods are proposed for the mechanicalevaluation of cervical spinal implant assemblies (see Fig.
39、 4,Fig. 6, and Fig. 8) and thoracolumbar, lumbar, and lumbosacralspinal implant assemblies (see Fig. 10, Fig. 12, and Fig. 14).4.2 Testing of the spinal implant assemblies will simulate avertebrectomy model via a large gap between two Ultra HighMolecular Weight Polyethylene (UHMWPE) test blocks. The
40、UHMWPE used to manufacture the test blocks should have atensile breaking strength equal to 40 6 3 MPa (see Specifica-tion D638). The UHMWPE test blocks (see Fig. 5, Fig. 7, Fig.9, Fig. 11, Fig. 13, and Fig. 15) will eliminate the effects of thevariability of bone properties and morphometry. Alternat
41、edesigns of test blocks may be used as long as equivalentperformance is demonstrated.4.3 Three static mechanical tests and one dynamic test willevaluate the spinal implant assemblies. The three static me-chanical tests are compression bending, tensile bending, andtorsion. The dynamic test is a compr
42、ession bending fatigue.FIG. 6 Cervical Bilateral Construct Test Setup for Screws or BoltsF1717 1154.4 A specific clinical indication generally requires a spe-cific spinal implant assembly. Spinal implant assemblies willbe evaluated with test configurations which simulate theclinical requirements for
43、 the intended spinal location. Theintended spinal locations are both anterior (see Fig. 4) andposterior (see Fig. 6 and Fig. 8) surfaces of the cervical spineor both anterior (see Fig. 10) and posterior (see Fig. 12 and Fig.14) surfaces of the thoracolumbar, lumbar, and lumbosacralspine. The block m
44、oment arm (see 6.6) for a test configurationdepends on the intended spinal location. The cervical spineconfiguration (see Fig. 5, Fig. 7, and Fig. 9) specifies one blockmoment arm, while a larger block moment arm (see Fig. 11,Fig. 13, and Fig. 15) is specified for the thoracolumbar, lumbar,and lumbo
45、sacral spine.4.5 The intended method of application of the spinal im-plant assembly may vary for specific anatomic regions andclinical indications. Spinal implant assemblies contain differenttypes of anchors. Each type of anchor has an intended methodof application to the spine. For example, one ass
46、embly mayinclude anterior vertebral body screws and rods (see Fig. 2),while another assembly may contain posterior sacral screws,hooks, rods, and transverse elements (see Fig. 3). The blockmoment arm of a test configuration will be independent of theintended method of application of a spinal implant
47、 assembly;therefore, the test data for different intended methods ofapplication may be compared.5. Significance and Use5.1 Spinal implants are generally composed of severalcomponents which, when connected together, form a spinalimplant assembly. Spinal implant assemblies are designed toprovide some
48、stability to the spine while arthrodesis takesplace. These test methods outline standard materials andmethods for the evaluation of different spinal implant assem-blies so that comparison between different designs may befacilitated.5.2 These test methods are used to quantify the static anddynamic me
49、chanical characteristics of different designs ofspinal implant assemblies. The mechanical tests are conductedin vitro using simplified load schemes and do not attempt tomimic the complex loads of the spine.FIG. 7 Cervical Bilateral UHMWPE Block for Screws or BoltsF1717 1165.3 The loads applied to the spinal implant assemblies invivo will, in general, differ from the loading configurationsused in these test methods. The results obtained here cannot beused directly to predict in vivo performance. The results can beused to compare different c
