1、Designation:F262407F262412 Standard Test Method for Static, Dynamic, and Wear Assessment of Extra-Discal Spinal Motion Preserving ImplantsSingle Level Spinal Constructs 1 This standard is issued under the xed designation F2624; the number immediately following the designation indicates the year of o
2、riginal adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval. 1. Scope 1.1 This test method is intended to provide test methods for the
3、 static, dynamic, and wear testing of extra-discal motion preserving implants. These implants are intended to augment spinal stability without signicant tissue removal while allowing motion of the functional spinal unit(s).describes methods to assess the static and dynamic properties of single level
4、 spinal constructs. 1.2 Wear is assessedAn option for assessing wear using a weight loss method and a dimensional analysis for determining wear of components used in extra-discal spinal motion preserving procedures, is given. This method, described herein, is used for the analysis of devices intende
5、d for motion preservation, using testing medium as dened in this test method standard (6.1). 1.3 This test method is not intended to address any potential failure mode as it relates to the xation of the device to its bony interfaces. 1.4 It is the intent of this test method to enable comparison of m
6、otion preserving, extra-discal implants single level extra-discal spinal constructs with regard to kinematic, functional, and wear characteristics when tested under the specied conditions. It must be recognized, however, that there are many possible variations in the in vivo conditions. A single lab
7、oratory simulation with a xed set of parameters may not be universally representative. 1.5 This test method is not intended to address facet arthroplasty devices. 1.6 This test method prescribes the use of pure angular rotations for assessing the mechanical characteristics of extra-discal motion pre
8、serving implants. This test method does not, however, prescribe methods for assessing the mechanical characteristics of the device in translation (for example, anterior/posterior translation), though this type of linear motion may be clinically relevant. 1.6 Inorderthatthedatabereproducibleandcompar
9、ablewithinandbetweenlaboratories,itisessentialthatuniformprocedures arebe established. This test method is intended to facilitate uniform testing methods and data reporting for extra-discal motion preserving implants. reporting. 1.7 Withoutasubstantialclinicalretrievalhistoryofspinal,motionpreservin
10、gextra-discalimplants,actualloadingprolesand patternscannotbedelineatedatthetimeofthewritingofthistestmethod.ItthereforefollowsthatthemotionprolesThemotion proles specied by this test method do not necessarily accurately reproduce those occurring in vivo. Rather this method provides useful boundary/
11、endpoint conditions for evaluating implant designs in a functional manner. 1.8 This test method is not intended to be a performance standard. It is the responsibility of the user of this test method to characterize the safety and effectiveness of the device under evaluation. 1.9 The values stated in
12、 SI units are to be regarded as the standard. The values given in parentheses are for information only. Multiple test methods are included in this standard. However, it must be noted that the user is not obligated to test using all of the described methods. Instead, the user should only select test
13、methods that are appropriate for a particular device design. In most instances, only a subset of the herein described test methods will be required. 1.10 The values stated in SI units are to be regarded as the standard with the exception of angular measurements, which may be reported in either degre
14、es or radians. No other units of measurement are included in this standard. 1 This test method is under the jurisdiction of ASTM Committee F04 on Medical and Surgical Materials and Devices and is the direct responsibility of Subcommittee F04.25 on Spinal Devices. Current edition approved Dec. 15, 20
15、07Dec. 1, 2012. Published March 2008February 2013. Originally approved in 2007. Last previous edition approved in 2007 as F158707. DOI: 10.1520/F2624-07.10.1520/F2624-12. This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes ha
16、ve been made to the previous version. Because it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version of the standard as published by ASTM is to be considered the official
17、document. Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States 11.12 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish
18、appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 1.11 Thistestmethoddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibility of the user of this test method to establish appropriate safety and health
19、 practices and to determine the applicability of regulatory limitations prior to use. 2. Referenced Documents 2.1 ASTM Standards: 2 E2309Practices for Verication of Displacement Measuring Systems and Devices Used in Material Testing Machines F561Practice for Retrieval and Analysis of Medical Devices
20、, and Associated Tissues and Fluids F1714Guide for Gravimetric Wear Assessment of Prosthetic Hip Designs in Simulator Devices F1717Test Methods for Spinal Implant Constructs in a Vertebrectomy Model F1877Practice for Characterization of Particles F2003Practice for Accelerated Aging of Ultra-High Mol
21、ecular Weight Polyethylene after Gamma Irradiation in Air F2423Guide for Functional, Kinematic, and Wear Assessment of Total Disc Prostheses 3. Terminology 3.1 All terminology is consistent with the referenced standards, unless otherwise stated. 3.2 Denitions: 3.2.1 center of rotation (COR)the point
22、 about which the simulated vertebral bodies rotate in performing the range of motion (ROM) specied in this test method. 2 ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatserviceastm.org.ForAnnualBookofASTMStandards volume information, refer to the standards
23、Document Summary page on the ASTM website. FIG. 13-D View of Extra-Discal Motion Preserving Implants in One Representative Testing CongurationTypical Force Displacement Curve F262412 23.2.2 compressive bending stiffness (N/mm)the compressive bending yield force divided by elastic displacement (see t
24、he initial slope of line BC in Fig. 1). 3.2.3 compressive bending ultimate load (N)the maximum compressive force in the X-Z plane applied to a spinal implant assembly(seetheforceatPointEinFig.1).Theultimateloadshouldbeafunctionofthedeviceandnotoftheloadcellortesting machine. 3.2.4 compressive bendin
25、g yield load (N)the compressive bending force in the X-Z plane necessary to produce a permanent deformation equal to 0.020 times the active length of the longitudinal element (see the force at Point D in Fig. 1). 3.2.5 coordinate system/axesthree orthogonal axes are dened following a right-handed Ca
26、rtesian coordinate system. The XY-plane plane is to bisect the sagittal plane between superior and inferior surfaces that are intended to simulate the adjacent vertebralendplates.ThepositiveZ-axisaxisistobedirectedsuperiorly.ForcecomponentsparalleltotheXY-planeplaneareshear componentsofloading.Theco
27、mpressiveaxialforceisdenedtobethecomponentinthenegativeZ-direction.direction.Torsional load is dened to be the component of moment about the Z-axis. 3.2.5.1 originthe center of the coordinate system is located at the center of rotation of the testing xture. 3.2.5.2 X-Axisthe positive X-Axis is a glo
28、bal xed axis relative to the testing machines stationary base and is to be directed anteriorly relative to the specimens initial unloaded position. 3.2.5.3 Y-AxisthepositiveY-Axisisaglobalxedaxisrelativetothetestingmachinesstationarybaseandisdirectedlaterally relative to the specimens initial unload
29、ed position. 3.2.5.4 Z-Axisthe positive Z-Axis is a global xed axis relative to the testing machines stationary base and is to be directed superiorly relative to the specimens initial unloaded position. 3.2.6 degradationloss of material or function or material properties due to causes other than tha
30、t associated with wear. 3.2.7 extra-discalmotionpreservingdeviceorimplantelasticdisplacement(mmordegrees)anon-biologicstructure,which lies entirely outside the intervertebral disc space and is intended to at leastthe displacement at 2% offset yield (see PointAin Fig. 1partially support the motion/lo
31、ad ) minus the 2% offset displacement (see Point B in Fig. 1between adjacent vertebral bodies. In this test). (The distance between Point A and Point B in Fig. 1method, this denition does not include facet arthroplasty devices) 3.2.8 uid absorptionuid absorbed by the device material during testing o
32、r while implanted in vivo. 3.2.9 functional failurepermanent deformation or wear that renders the extra-discal motion preserving implant assembly ineffective or unable to adequately resist load/motion or any secondary effects that result in a reduction of clinically relevant motions or the motions i
33、ntended by the design of the device. 3.2.7 functional spinal unit (FSU)two adjacent vertebrae, including the intervertebral disc, and all adjoining ligaments between them, specically excluding all other connective tissues such as muscles (Ref (1). 3 3.2.10 interval net volumetric wear rateVR i durin
34、g cycle interval i (mm 3 /million cycles): VR i 5 WR i r where: where: r = mass density (for example, units of g/mm 3 ) of the wear material. 3.2.11 interval net wear rateWR i during cycle interval i (g/million(mg/million cycles): WR i 5 NW i 2NW i21 ! #ofcyclesinintervali! 310 6 Note,Note: for i=1,
35、 NW i1 =0. 3.2.12 kinematic prolethe relative motion between adjacent vertebral bodies that the extra-discal motion preserving spinal device is subjected to while being tested.tested (note that rigid devices may have minimal motion between vertebral bodies). 3.2.13 maximum run out force or momentthe
36、 maximum force or moment for a given test that can be applied to a single level construct intended for fusion in which all of the tested constructs have withstood 5000000 cycles without functional or mechanical failure. For non-fusion devices, the maximum run out force or moment is dened as 10000000
37、 cycles without functional or mechanical failure. 3.2.14 mechanical failurefailure associated with a defect in the material (for example, fatigue crack) or of the bonding between materials that may or may not produce functional failure. 3.2.15 net volumetric wearNV i of wear specimen (mm 3 ): F26241
38、2 3NV i 5 NW i r at end of cycle interval i. where: where: r = mass density (for example, units of g/mm 3 ) of the wear material. 3.2.16 net wearNW i of wear specimen (g): NW i 5W 0 2W i !1S i 2S 0 ! Loss in weight of the wear specimen corrected for uid absorption at end of cycle interval i. 3.2.17
39、originpermanent deformationthe center of the coordinate system is located at the center of rotation of the testing xture.remaining displacement (mm) or angular rotation (degrees) relative to the initial unloaded condition of the intervertebral body fusion device assembly after the applied force has
40、been removed. 3.2.18 run-out (cycles)the maximum number of cycles that a test needs to be carried to if functional failure has not yet occurred. 3.2.19 single level spinal constructa non-biologic structure, which lies entirely outside the intervertebral disc space, intended to support the full or pa
41、rtial load between adjacent vertebral bodies. In this test method, this denition does not include facet arthroplasty devices. 3.2.20 stiffness (N/mm or N-m/degree)(The Slope of Line OGFig. 1)the slope of the initial linear portion of the force-displacement or moment-degree curve. 3.2.21 test blockth
42、e component of the test apparatus for mounting a single level spinal construct for the intended test conguration (Fig. 3). 3.2.22 torsional aspect ratiothe active length of the longitudinal element divided by the distance from the center of rotation to the insertion point of an anchor (for example:
43、0.78 for a 35 mm active length, X = 40 mm and Y = 40/2 mm). NOTE 1This example depicts a 3D rendering of a possible method for implementing of the rotational testing apparatus. In this example, adjustment mechanismsareemployedtoimpartbothaxialload(Fz)andaspondylolisthesisoffsetpriortolockingthespina
44、lassemblyintheapparatus.Theactuator isrotatedtoapplyexion/extensionmoments.Spinalconstructsarealsotestedinlateralbendingandaxialtorsioninthissametestsetupwithappropriate modications. FIG. 2Extra-Discal Motion Preserving Implants in One Representative Testing CongurationRotational Testing Apparatus F
45、262412 43.2.23 two percent (2%) offset angular displacement (degrees)a permanent angular displacement in the X-Y plane measured via the actuator equal to 0.020 times the torsional aspect ratio (for example: 0.9 for 0.78 0.02 180/pi) (see Point B in Fig. 1). 3.2.24 2% offset displacement(Distance OBF
46、ig. 1)a permanent deformation measured via the actuator equal to 0.020 times the active length of the longitudinal element (for example: 1.04 mm for a 52 mm active length) (see Point B in Fig. 1). 3.2.25 wearthe progressive loss of material from the device(s) or device components as a result of rela
47、tive motion at the surface with another body as measured by the change in mass of the components of the implants. Or in the case of a non-articulating, compliant device,components, wear is dened simply as the loss of material from the device. Note that bone interface components of the device are exc
48、luded from this denition (seedenition; see 5.2.2, 5.2.4, and 5.2.5). . 3.2.26 weight S i of soak control specimen (g)S 0 initial and S i at end of cycle interval i. 3.2.27 weight W i of wear specimen (g)W 0 initial and W i at end of cycle interval i. 3.2.28 ultimate displacement (mm or degrees)(Disp
49、lacement OFFig. 1)the displacement associated with the ultimate force. 3.2.29 X-axisultimateload(NorN-m)thepositive(PointEFig.1)theXmaximumapplied-axisisforce,aF,globalxed axis relative to the testing machines stationary base and is to be directed anteriorly relative to the specimens initial unloaded position.transmitted by the actuator that can be applied to the spinal construct. 3.2.30 Y-axisyield displacementthe positive(Distance OAFig. 1)the Ydisplacement (mm-axis is a glo
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