1、Designation: F2789 10 (Reapproved 2015)Standard Guide forMechanical and Functional Characterization of NucleusDevices1This standard is issued under the fixed designation F2789; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the ye
2、ar 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 guide describes various forms of nucleus replace-ment and nucleus augmentation devices. It further outlines
3、 thetypes of testing that are recommended in evaluating theperformance of these devices.1.2 Biocompatibility of the materials used in a nucleusreplacement device is not addressed in this guide. However,users should investigate the biocompatibility of their deviceseparately (see X1.1).1.3 While it is
4、 understood that expulsion and endplatefractures represent documented clinical failures, this guidedoes not specifically address them, although some of thefactors that relate to expulsion have been included (see X1.3).1.4 Multiple tests are described in this guide; however, theuser need not use them
5、 all. It is the responsibility of the user ofthis guide to determine which tests are appropriate for thedevices being tested and their potential application. Some testsmay not be applicable for all types of devices. Moreover, somenucleus devices may not be stable in all test configurations.However,
6、this does not necessarily mean that the test methodsdescribed are unsuitable.1.5 The science of nucleus device design is still very youngand includes technology that is changing more quickly thanthis guide can be modified. Therefore, the user must carefullyconsider the applicability of this guide to
7、 the users particulardevice; the guide may not be appropriate for every device. Forexample, at the time of publication, this guide does not addressthe nucleus replacement and nucleus augmentation devices thatare designed to be partially or completely resorbable in thebody. However, some of the test
8、recommended in this guidemay be applicable to evaluate such devices. It has not beendemonstrated that mechanical failure of nucleus devices isrelated to adverse clinical results. Therefore this standardshould be used with care in evaluating proposed nucleusdevices.1.6 This guide is not intended to b
9、e a performance standard.It is the responsibility of the user of this guide to characterizethe safety and effectiveness of the nucleus device underevaluation.1.7 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard. Angular measureme
10、nts may be reported in eitherdegrees or radians.1.8 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 reg
11、ulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D2990 Test Methods for Tensile, Compressive, and FlexuralCreep and Creep-Rupture of PlasticsD6204 Test Method for RubberMeasurement of Unvulca-nized Rheological Properties Using Rotorless Shear Rhe-ometersE6 Terminology Rela
12、ting to Methods of Mechanical TestingE111 Test Method for Youngs Modulus, Tangent Modulus,and Chord ModulusE132 Test Method for Poissons Ratio at Room TemperatureE328 Test Methods for Stress Relaxation for Materials andStructuresE1823 Terminology Relating to Fatigue and Fracture TestingF561 Practice
13、 for Retrieval and Analysis of MedicalDevices, and Associated Tissues and FluidsF1582 Terminology Relating to Spinal ImplantsF1714 Guide for Gravimetric WearAssessment of ProstheticHip Designs in Simulator DevicesF1877 Practice for Characterization of ParticlesF1980 Guide for Accelerated Aging of St
14、erile Barrier Sys-tems for Medical DevicesF2267 Test Method for Measuring Load Induced Subsidence1This test method is under the jurisdiction ofASTM Committee F04 on Medicaland Surgical Materials and Devices and is the direct responsibility of SubcommitteeF04.25 on Spinal Devices.Current edition appr
15、oved May 1, 2015. Published July 2015. Originally approvedin 2010. Last previous edition approved in 2010 as F2789 10. DOI: 10.1520/F2789-10R15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards v
16、olume 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 States1of Intervertebral Body Fusion Device Under Static AxialCompressionF2346 Test Methods for Static and Dyn
17、amic Characteriza-tion of Spinal Artificial DiscsF2423 Guide for Functional, Kinematic, and Wear Assess-ment of Total Disc Prostheses2.2 Other Standards:3ISO 10993 Biological Evaluation of Medical Devices: Parts120ISO 181921 Implants for SurgeryWear of Total Interver-tebral Spinal Disc Prostheses3.
18、Terminology3.1 For definition of terms, refer to Terminologies E6,E1823, and F1582.3.2 Definitions:3.2.1 coordinate system/axes, nThree orthogonal axes aredefined by Terminology F1582. The center of the coordinatesystem is located at the geometric center of the native disc.Because of design intent,
19、or procedural limitations, the devicemight not be implanted at the center of the native disc;therefore, the geometric center of the disc might not be thegeometric center of the device. For uniformity in comparisonbetween devices, it is important that the origin be placed withrespect to the disc, not
20、 the device. This is done so that allloading is consistently applied and measurement made withrespect to the anatomy of the spine, and not with respect to thedevice. The XY plane bisects the sagittal plane betweensuperior and inferior surfaces that are intended to simulate theadjacent vertebral endp
21、lates. The positive X axis is to bedirected anteriorly. The positive Z axis is to be directedsuperiorly. Shear components of loading are defined to be thecomponents parallel to the XY plane. The compressive axialforce is defined to be the component in either the positive ornegative Z direction depen
22、ding on the test frame set-up.Torsional load is defined as the component of moment aboutthe Z axis.3.2.2 energy absorption, nThe work or energy (in joules)that a material can store, temporarily or permanently, after agiven stress is applied and then released.3.2.3 expulsion, na condition during test
23、ing when thedevice or a component of the device becomes fully displaced ordislodged from its implanted position (that is, in the directionof shear) through a surrogate annulus, or enclosure used tosimulate an annular boundary. Expulsion may be considered aspecific type of migration and for the purpo
24、ses of this standardis only useful when the testing is being conducted within asurrogate annulus or enclosure.3.2.4 extrusion, na condition during testing when a por-tion of a device displaces through a surrounding membrane orenclosure but does not separate from the rest of the device.Extrusion may
25、be considered a specific type of migration andfor the purposes of this standard is only useful when the testingis being conducted within a surrogate annulus or enclosure.3.2.5 fatigue life, nThe number of cycles, N, that thenucleus device can sustain at a particular load or momentbefore functional o
26、r mechanical failure occurs.3.2.6 functional failure, nA failure that renders thenucleus device ineffective or unable to resist load or function aspredetermined within desired parameters (for example, perma-nent deformation, dissociation, dehydration, expulsion, extru-sion or fracture), or both.3.2.
27、6.1 DiscussionFunctional failure may or may not becorrelated with clinical failure.3.2.7 hysteresis, nThe resultant loop on a force displace-ment plot that is created from a mechanical test performed ona viscoelastic material. The area inside the loop can be used todetermine the energy absorption.3.
28、2.8 mechanical failure, nA failure associated with theonset of a defect in the material (for example, a fatiguefracture, a static fracture, or surface wear).3.2.8.1 DiscussionAmechanical failure can occur withoutthere being a functional failure.3.2.9 migration, nA condition during testing when adevi
29、ce displaces from its original position during testing.Migration may or may not be considered a specific type offunctional failure. The user is expected to define their criteriafor acceptable levels of migration and provide rationale forthose criteria. See also definitions for expulsion, extrusion,
30、andsubsidence.3.2.10 nucleus device, nA generic term that refers to alltypes of devices intended to replace or augment the nucleuspulposus in the intervertebral disc. Adjectives can be added tothe term “nucleus device” to more thoroughly describe thedevices intended function. Terms 3.2.10.1 through
31、3.2.10.9will be used to address specific types of nucleus devicesthroughout the rest of this guide. These terms may not apply toall nucleus devices and some combinations of terms may beapplicable to certain devices. However, this term should not beused interchangeably with annular repair device.3.2.
32、10.1 complete nucleus replacement device, nAnucleus device that is designed to replace most or all ( 50 %by volume) of the nucleus pulposus of the intervertebral disc.3.2.10.2 partial nucleus replacement device, nA nucleusdevice that is designed to replace some ( 50 % by volume) ofthe nucleus pulpos
33、us of the intervertebral disc.3.2.10.3 nucleus augmentation device, nA nucleus devicethat is designed to supplement or augment, but not replace, theexisting nucleus pulposus in the intervertebral disc.3.2.10.4 encapsulated nucleus device, nA nucleus devicethat includes an outer jacket, bag, or a sim
34、ilar casing, which inturn interfaces directly with the in vivo environment.3.2.10.5 open nucleus device, nA nucleus device that isnot encased. The material interfaces directly with the in vivoenvironment.3.2.10.6 in situ formed nucleus device, nA nucleus devicethat is introduced into the disc space
35、without a predeterminedgeometry. This may include injectable, in situ curing orpolymerizing nucleus devices.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.F2789 10 (2015)23.2.10.7 preformed nucleus device, nA nucleus dev
36、icethat is introduced into the disc space already in apredetermined, but not necessarily final, geometry with allchemical processes completed prior to insertion.3.2.10.8 non-hydrated nucleus device, nA nucleus devicethat does not require water to be present to achieve its intendedpurposes.3.2.10.9 h
37、ydrated nucleus device, nA nucleus device thatrequires water to be present to achieve its intended purposes.3.2.11 Range of Motion (ROM), nThe difference betweenthe minimum and maximum displacement or angular displace-ment of the nucleus device that occurs during a test. Thisparameter may be useful
38、when a surrogate annulus is used fortesting.3.2.12 secant stiffness, nFor a given applied load orapplied displacement: (maximum load) (minimum load)/(maximum displacement) (minimum displacement).3.2.13 stiffness, nThe slope of the linear portion of theload-displacement curve or of the moment-angular
39、 displace-ment curve at a segment within normal physiologic parameters.If there is no linear portion, then stiffness may be estimatedusing other standard methods such as those found in TestMethod E111 (chord or tangential stiffness, or both) withinnormal physiologic parameters.3.2.14 subsidence, nSe
40、ttling or migration of the deviceinto the inferior or superior interfaces adjacent to the device.Subsidence may be considered a specific type of migration and,for the purposes of this standard, is only useful when themating endplates, fixtures or surrogate annulus have a modulusthat allows subsidenc
41、e to occur.4. Summary of Test Method4.1 The tests for characterizing the performance of nucleusdevices can include one or more of the following: static anddynamic axial compression, axial torsion, and shear tests,functional range of motion, subsidence, mechanical behaviorchange due to aging, swellin
42、g pressure, and viscoelastictesting. Table 1 summarizes these tests with reference tosections where they are described in more detail. Additionally,Table 1 also lists additional reference documents that may beapplicable to each particular test.4.2 Some tests may not be applicable for all types of nu
43、cleusdevices.4.3 Where appropriate, a surrogate annulus may be used tofurther characterize the nucleus device.4.4 All tests shall be performed on the nucleus device in thesame shape, size, and condition as it would be used clinicallyunless adequately justified (that is, if gamma radiation is to beus
44、ed to sterilize the device, or the device is meant to functionin a hydrated state, then all tests should be performed ongamma-irradiated or hydrated parts or a justification shall bemade).4.5 Nucleus devices shall be tested statically to failure andalso tested cyclically to estimate the maximum run
45、out load ormoment at 10 106cycles. Depending on the test and intendeduse, the devices can be tested in force control or in positioncontrol, but in either case, the control mode should be justified.5. Significance and Use5.1 Nucleus devices are generally designed to augment themechanical function of
46、native degenerated nucleus material orto replace tissue that has been removed during a surgicalprocedure. This guide outlines methods for evaluating manydifferent types of devices. Comparisons between devices mustbe made cautiously and with careful analysis, taking intoaccount the effects that desig
47、n and functional differences canhave on the testing configurations and overall performance,and the possibility that mechanical failure may not be related toclinical failure and inversely, that mechanical success may notbe related to clinical success.5.2 These tests are conducted in vitro to allow fo
48、r analysisof the mechanical performance of the nucleus device underspecific testing modalities. The loads applied may differ fromthe complex loading seen in vivo, and therefore the results fromthese tests may not directly predict in vivo performance.5.3 These tests are used to quantify the static an
49、d dynamicproperties and performance of different implant designs. TheTABLE 1 Summary of Test MethodsTest Grouping Test Type Boundary and SampleConditionsSection of this Standard Applicable Standard orReferenceStatic Axial CompressionAxial TorsionShearBendingAs ManufacturedWith Surrogate AnnulusSimulated AgedWith Surrogate Annulusand Simulated Aged7.27.1 and 7.27.2 and 7.77.1, 7.2, and 7.7Test Methods F2346Dynamic(Fatigue and Wear)Axial CompressionAxial TorsionShearBendingAs ManufacturedWith Surrogate AnnulusSimulated AgedWith Surrogate An
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