1、Designation: F2789 10Standard 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 year of last revisio
2、n. 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 thetypes of testi
3、ng 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 understood that e
4、xpulsion 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 all. It is the re
5、sponsibility 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, this does not nece
6、ssarily 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 the users particu
7、lardevice; 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 recommended in thi
8、s 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 be a performance st
9、andard.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 measurements may be reporte
10、d 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 regulatory limitation
11、s prior to use.2. Referenced Documents2.1 ASTM Standards:2D2990 Test Methods for Tensile, Compressive, and Flex-ural Creep and Creep-Rupture of PlasticsD6204 Test Method for RubberMeasurement of Unvul-canized Rheological Properties Using Rotorless ShearRheometersE6 Terminology Relating to Methods of
12、 Mechanical TestingE111 Test Method for Youngs Modulus, Tangent Modulus,and Chord ModulusE132 Test Method for Poissons Ratio at Room Tempera-tureE328 Test Methods for Stress Relaxation for Materials andStructuresE1823 Terminology Relating to Fatigue and Fracture Test-ingF561 Practice for Retrieval a
13、nd Analysis of Medical De-vices, and Associated Tissues and FluidsF1582 Terminology Relating to Spinal ImplantsF1714 Guide for Gravimetric Wear Assessment of Pros-thetic Hip Designs in Simulator DevicesF1877 Practice for Characterization of Particles1This test method is under the jurisdiction of AST
14、M Committee F04 on Medicaland Surgical Materials and Devices and is the direct responsibility of SubcommitteeF04.25 on Spinal Devices.Current edition approved June 1, 2010. Published July 2010. DOI: 10.1520/F278910.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM
15、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.F1980 Guide for Accelerated Agi
16、ng of Sterile Barrier Sys-tems for Medical DevicesF2267 Test Method for Measuring Load Induced Subsid-ence of Intervertebral Body Fusion Device Under StaticAxial CompressionF2346 Test Methods for Static and Dynamic Characteriza-tion of Spinal Artificial DiscsF2423 Guide for Functional, Kinematic, an
17、d 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. Terminology3.1 For definition of terms, refer to Terminologies E6,E1823, and F1582.3.2 Def
18、initions: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, or procedural limitations, the devicemight not be implanted at the center of the native di
19、sc;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 the device. This is done so that allloading is consistently applied and measurement made
20、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 endplates. The positive X axis is to bedirected anteriorly. The positive Z axis is to be direc
21、tedsuperiorly. 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 depending on the test frame set-up.Torsional load is defined as the component of moment aboutth
22、e 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 testing when thedevice or a component of the device becomes fully displaced ordislodged from i
23、ts 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 purposes of this standardis only useful when the testing is being conducted within asurrogate a
24、nnulus 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 be considered a specific type of migration andfor the purposes of this standard is only us
25、eful 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 or mechanical failure occurs.3.2.6 functional failure, nA failure that renders thenucleus d
26、evice 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.3.2.6.1 DiscussionFunctional failure may or may not becorrelated with clinical failure.3.2.7 h
27、ysteresis, 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.3.2.8 mechanical failure, nA failure associated with theonset of a defect in the material (f
28、or 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 adevice displaces from its original position during testing.Migration may or may not be conside
29、red 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, andsubsidence.3.2.10 nucleus device, nA generic term that refers to alltypes of devices in
30、tended 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 3.2.10.9will be used to address specific types of nucleus devicesthroughout the rest of th
31、is 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.3.2.10.1 complete nucleus replacement device, nAnucleus device that is designed to replace mos
32、t 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 pulposus of the intervertebral disc.3.2.10.3 nucleus augmentation device, nA nucleus devicethat
33、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 similar casing, which inturn interfaces directly with the in vivo environment.3.2.10.5 open n
34、ucleus 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 without a predeterminedgeometry. This may include injectable, in situ curing orpolymerizin
35、g nucleus devices.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.F2789 1023.2.10.7 preformed nucleus device, nA nucleus devicethat is introduced into the disc space already in a predeter-mined, but not necessarily final,
36、 geometry with all chemicalprocesses 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 hydrated nucleus device, nA nucleus device thatrequires water to be present to achieve its inten
37、ded 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 when a surrogate annulus is used fortesting.3.2.12 secant stiffness, nFor a given applied load
38、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 displace-ment curve at a segment within normal physiologic parameters.If there is no linear po
39、rtion, 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, nSettling or migration of the deviceinto the inferior or superior interfaces adjacent to the devic
40、e.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 subsidence to occur.4. Summary of Test Method4.1 The tests for characterizing the performance of nucleus
41、devices 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, swelling pressure, and viscoelastictesting. Table 1 summarizes these tests with reference tosections w
42、here 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 nucleusdevices.4.3 Where appropriate, a surrogate annulus may be used tofurther characterize the
43、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 beused to sterilize the device, or the device is meant to functionin a hydrated state, then all tes
44、ts 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 out load ormoment at 10 3 106cycles. Depending on the test andintended use, the devices can be
45、tested in force control or inposition control, but in either case, the control mode should bejustified.5. Significance and Use5.1 Nucleus devices are generally designed to augment themechanical function of native degenerated nucleus material orto replace tissue that has been removed during a surgica
46、lprocedure. 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 design and functional differences canhave on the testing configurations and overall performance,TAB
47、LE 1 Summary of Test MethodsTest Grouping Test Type Boundary and SampleConditionsSection of this Standard Applicable Standard or ReferenceStaticAxial CompressionAxial TorsionShearBendingAs ManufacturedWith Surrogate AnnulusSimulated AgedWith Surrogate Annulusand Simulated Aged7.27.1 and 7.27.2 and 7
48、.77.1, 7.2, and 7.7Test Methods F2346Dynamic(Fatigue and Wear)Axial CompressionAxial TorsionShearBendingAs ManufacturedWith Surrogate AnnulusSimulated AgedWith Surrogate Annulusand Simulated Aged7.37.1 and 7.37.3 and 7.77.1, 7.3, and 7.7Test Methods F2346, Guide F2423andISO 181921Functional TestingF
49、unctional Range of MotionLifting ForceViscoelastic TestingSubsidenceAs Manufactured(After simulated aging and withsurrogate annulus whereapplicable)7.3.6(7.1 and 7.7 where applicable)7.4(7.1 and 7.7 where applicable)7.5(7.1 and 7.7 where applicable)7.6(7.1 and 7.7 where applicable)Wilke, 1998 (3)Catellani, 1989 (4)Test Methods D2990Test Method F2267F2789 103and 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 conduc
