1、Designation: F2624 12 (Reapproved 2016)Standard Test Method forStatic, Dynamic, and Wear Assessment of Extra-DiscalSingle Level Spinal Constructs1This standard is issued under the fixed designation F2624; 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 test method describes methods to assess the staticand dynamic properties of sin
3、gle level spinal constructs.1.2 An option for assessing wear using a weight loss methodand a dimensional analysis is given. This method, describedherein, is used for the analysis of devices intended for motionpreservation, using testing medium as defined in this standard(6.1).1.3 This test method is
4、 not intended to address any potentialfailure mode as it relates to the fixation of the device to its bonyinterfaces.1.4 It is the intent of this test method to enable single levelextra-discal spinal constructs with regard to kinematic,functional, and wear characteristics when tested under thespecif
5、ied conditions.1.5 This test method is not intended to address facetarthroplasty devices.1.6 In order that the data be reproducible and comparablewithin and between laboratories, it is essential that uniformprocedures be established. This test method is intended tofacilitate uniform testing methods
6、and data reporting.1.7 The motion profiles specified by this test method do notnecessarily accurately reproduce those occurring in vivo.Rather this method provides useful boundary/endpoint condi-tions for evaluating implant designs in a functional manner.1.8 This test method is not intended to be a
7、performancestandard. It is the responsibility of the user of this test methodto characterize the safety and effectiveness of the device underevaluation.1.9 Multiple test methods are included in this standard.However, it must be noted that the user is not obligated to testusing all of the described m
8、ethods. Instead, the user shouldonly select test methods that are appropriate for a particulardevice design. In most instances, only a subset of the hereindescribed test methods will be required.1.10 The values stated in SI units are to be regarded as thestandard with the exception of angular measur
9、ements, whichmay be reported in either degrees or radians. No other units ofmeasurement are included in this standard.1.11 This test method does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this test method to establishappr
10、opriate safety and health practices and to determine theapplicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E2309 Practices for Verification of Displacement MeasuringSystems and Devices Used in Material Testing MachinesF561 Practice for Retrieval and Analy
11、sis of MedicalDevices, and Associated Tissues and FluidsF1714 Guide for Gravimetric WearAssessment of ProstheticHip Designs in Simulator DevicesF1717 Test Methods for Spinal Implant Constructs in aVertebrectomy ModelF1877 Practice for Characterization of ParticlesF2003 Practice for Accelerated Aging
12、 of Ultra-High Mo-lecular Weight Polyethylene after Gamma Irradiation inAirF2423 Guide for Functional, Kinematic, and Wear Assess-ment of Total Disc Prostheses3. Terminology3.1 All terminology is consistent with the referencedstandards, unless otherwise stated.3.2 Definitions:3.2.1 center of rotatio
13、n (COR)the point about which thesimulated vertebral bodies rotate in performing the range ofmotion (ROM) specified in this test method.1This test method is under the jurisdiction ofASTM Committee F04 on Medicaland Surgical Materials and Devices and is the direct responsibility of SubcommitteeF04.25
14、on Spinal Devices.Current edition approved Dec. 1, 2016. Published December 2016. Originallyapproved in 2007. Last previous edition approved in 2012 as F2624 12. DOI:10.1520/F2624-12R16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceas
15、tm.org. For Annual Book of ASTMStandards volume information, 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 StatesThis international standard was developed in accordance with i
16、nternationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.2.2 compressive bending stiffness (N/mm)th
17、e compres-sive bending yield force divided by elastic displacement (seethe initial slope of line BC in Fig. 1).3.2.3 compressive bending ultimate load (N)the maxi-mum compressive force in the X-Z plane applied to a spinalimplant assembly (see the force at Point E in Fig. 1). Theultimate load should
18、be a function of the device and not of theload cell or testing machine.3.2.4 compressive bending yield load (N)the compressivebending force in the X-Z plane necessary to produce apermanent deformation equal to 0.020 times the active lengthof the longitudinal element (see the force at Point D in Fig.
19、 1).3.2.5 coordinate system/axesthree orthogonal axes aredefined following a right-handed Cartesian coordinate system.The XY plane is to bisect the sagittal plane between superiorand inferior surfaces that are intended to simulate the adjacentvertebral end plates. The positive Z axis is to be direct
20、edsuperiorly. 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 about the Z-axis.3.2.5.1 originthe center of the coordinate system is
21、lo-cated at the center of rotation of the testing fixture.3.2.5.2 X-Axisthe positive X-Axis is a global fixed axisrelative to the testing machines stationary base and is to bedirected anteriorly relative to the specimens initial unloadedposition.3.2.5.3 Y-Axisthe positive Y-Axis is a global fixed ax
22、isrelative to the testing machines stationary base and is directedlaterally relative to the specimens initial unloaded position.3.2.5.4 Z-Axisthe positive Z-Axis is a global fixed axisrelative to the testing machines stationary base and is to bedirected superiorly relative to the specimens initial u
23、nloadedposition.3.2.6 degradationloss of material or function or materialproperties due to causes other than that associated with wear.3.2.7 elastic displacement (mm or degrees)the displace-ment at 2 % offset yield (see Point A in Fig. 1) minus the 2 %offset displacement (see Point B in Fig. 1). (Th
24、e distancebetween Point A and Point B in Fig. 1.)3.2.8 fluid absorptionfluid absorbed by the device mate-rial during testing or while implanted in vivo.3.2.9 functional failurepermanent deformation or wearthat renders the implant assembly ineffective or unable toadequately resist load/motion or any
25、secondary effects thatFIG. 1 Typical Force Displacement CurveF2624 12 (2016)2result in a reduction of clinically relevant motions or themotions intended by the design of the device.3.2.10 interval net volumetric wear rateVRiduring cycleinterval i (mm3/million cycles):VRi5WRiwhere: = mass density (fo
26、r example, units of g/mm3) of the wearmaterial.3.2.11 interval net wear rateWRiduring cycle interval i(mg/million cycles):WRi5NWi2 NWi21!# of cycles in interval i)3106Note: for i =1,NWi1=0.3.2.12 kinematic profilethe relative motion between adja-cent vertebral bodies that the spinal device is subjec
27、ted to whilebeing tested (note that rigid devices may have minimal motionbetween vertebral bodies).3.2.13 maximum run out force or momentthe maximumforce or moment for a given test that can be applied to a singlelevel construct intended for fusion in which all of the testedconstructs have withstood
28、5 000 000 cycles without functionalor mechanical failure. For non-fusion devices, the maximumrun out force or moment is defined as 10 000 000 cycleswithout functional or mechanical failure.3.2.14 mechanical failurefailure associated with a defectin the material (for example, fatigue crack) or of the
29、 bondingbetween materials that may or may not produce functionalfailure.3.2.15 net volumetric wearNViof wear specimen (mm3):NVi5NWiat end of cycle interval i.where: = mass density (for example, units of g/mm3) of the wearmaterial.3.2.16 net wearNWiof wear specimen (g):NWi5 W02 Wi!1Si2 S0!Loss in wei
30、ght of the wear specimen corrected for fluid ab-sorption at end of cycle interval i.3.2.17 permanent deformationthe remaining displace-ment (mm) or angular rotation (degrees) relative to the initialunloaded condition of the intervertebral body fusion deviceassembly after the applied force has been r
31、emoved.3.2.18 run-out (cycles)the maximum number of cyclesthat a test needs to be carried to if functional failure has not yetoccurred.3.2.19 single level spinal constructa non-biologicstructure, which lies entirely outside the intervertebral discspace, intended to support the full or partial load b
32、etweenadjacent vertebral bodies. In this test method, this definitiondoes not include facet arthroplasty devices.3.2.20 stiffness (N/mm or N-m/degree)(The Slope of LineOGFig. 1)the slope of the initial linear portion of theforce-displacement or moment-degree curve.3.2.21 test blockthe component of t
33、he test apparatus formounting a single level spinal construct for the intended testconfiguration (Fig. 3).3.2.22 torsional aspect ratiothe active length of the lon-gitudinal element divided by the distance from the center ofrotation to the insertion point of an anchor (for example: 0.78for a 35 mm a
34、ctive length, X =40mmandY = 40/2 mm).3.2.23 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: 0.9 for 0.78 0.02 180/pi) (seePoint B in Fig. 1).3.2.24 2 % offset
35、 displacement(Distance OBFig. 1)apermanent deformation measured via the actuator equal to0.020 times the active length of the longitudinal element (forexample: 1.04 mm for a 52 mm active length) (see Point B inFig. 1).3.2.25 wearthe progressive loss of material from thedevice(s) or device components
36、 as a result of relative motion atthe surface with another body as measured by the change inmass of the components of the implants. Or in the case ofnon-articulating, compliant components, wear is defined sim-ply as the loss of material from the device. Note that boneinterface components of the devi
37、ce are excluded from thisdefinition; see 5.2.2, 5.2.4, and 5.2.5.3.2.26 weight Siof soak control specimen (g)S0initial andSiat end of cycle interval i.3.2.27 weight Wiof wear specimen (g)W0initial and Wiatend of cycle interval i.3.2.28 ultimate displacement (mm or degrees)(Displacement OFFig. 1)the
38、displacement associated withthe ultimate force.3.2.29 ultimate load (N or N-m)(Point EFig. 1)themaximum applied force, F, transmitted by the actuator that canbe applied to the spinal construct.3.2.30 yield displacement(Distance OAFig. 1)thedisplacement (mm or degrees) when a spinal construct has ape
39、rmanent deformation equal to the offset displacement.3.2.31 yield force(Point DFig. 1)the applied force, F,or moment transmitted by the actuator required to produce apermanent deformation equal to the offset displacement.4. Significance and Use4.1 This test method is designed to quantify the static
40、anddynamic characteristics of different designs of single levelspinal constructs. Wear may also be assessed for implants thatallow motion using testing medium (see 6.1) for simulating thephysiologic environment at 37C. Wear is assessed using aweight loss method in addition to dimensional analyses.We
41、ight loss is determined after subjecting the implants todynamic profiles specified in this test method. This informationwill allow the manufacturer or end user of the product toF2624 12 (2016)3understand how the specific device in question performs underthe test conditions prescribed in this test me
42、thod.4.2 This test method is intended to be applicable for singlelevel extra-discal spinal constructs. Three different types offixtures are specified for testing single level extra-discal spinalconstructs (See Fig. 2, Fig. 4, and Fig. 5). See also Table 1.4.3 Implants may be designed using a variety
43、 of materials(for example, ceramics, metals, polymers, or combinationsthereof), and it is the goal of this test method to enable acomparison of the static, dynamic, and wear properties gener-ated by these devices, regardless of material and type of device.5. Apparatus5.1 Implant ComponentsThe device
44、 may comprise a va-riety of shapes and configurations. Some known forms includescrews which rigidly purchase the vertebral bodies coupledwith flexible, elastic members; other forms may include rigidmembers coupled in a constrained (for example, pediclescrews) or semi-constrained manner (for example,
45、 screws androds connected with a universal joint with defined motionlimitations). Forms of these devices which employ hooks thatengage posterior spinal elements are also envisioned; thesedevices may support extension loading only or loads in bothflexion and extension.5.2 Spinal Testing Apparatus:5.2
46、.1 Test ChambersIn the case of a multi-specimenmachine being used with testing medium, each chamber shallbe isolated to prevent cross-contamination of the test speci-mens. The chamber shall be made entirely of non-corrosivecomponents, such as acrylic plastic or stainless steel, and shallbe easy to r
47、emove from the machine for thorough cleaningbetween tests.5.2.2 For wear testing, the test chamber also must isolate thedevice/construct from wear centers created by the testingfixtures.5.2.3 The user must determine the appropriate degrees offreedom for the device depending on its intended use (see5
48、.2.6).5.2.4 Component Clamping/FixturingSince one of thepurposes may be to characterize the wear properties of thespinal device, the method for mounting components in the testchamber shall not compromise the accuracy of assessment ofthe weight loss or stiffness variation during the test. Forexample,
49、 implants having complicated surfaces for contactingbone (for example, sintered beads, hydroxylapatite (HA)coating, plasma spray) may be specially manufactured tomodify that surface in a manner that does not affect the wearsimulation.5.2.5 The device should be securely (rigidly) attached at itsbone-implant interface to the test fixtures.NOTE 1This example depicts a 3D rendering of a possible method for implementing of the rotational testing apparatus. In this example, adjustmentmechanisms are employed to impa
