1、Designation: F 2706 08Standard Test Methods forOccipital-Cervical and Occipital-Cervical-Thoracic SpinalImplant Constructs in a Vertebrectomy Model1This standard is issued under the fixed designation F 2706; the number immediately following the designation indicates the year oforiginal adoption or,
2、in 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 These test methods cover the materials and methods forthe static and fatigue test
3、ing of occipital-cervical and occipital-cervical-thoracic spinal implant assemblies in a vertebrectomymodel. The test materials for most combinations of occipital-cervical and occipital-cervical-thoracic spinal implant compo-nents can be specific depending on the intended location andintended method
4、 of attachment.1.2 These test methods are intended to provide a basis forthe mechanical comparison among past, present, and futureoccipital-cervical and occipital-cervical-thoracic spinal im-plant assemblies. They allow comparison of occipital-cervicaland occipital-cervical-thoracic spinal implant c
5、onstructs withdifferent methods of application to the spine. These testmethods are not intended to define levels of performance, sincesufficient knowledge is not available to predict the conse-quences of the use of a particular device.1.3 These test methods set out guidelines for load types andmetho
6、ds of applying loads. Methods for three static load typesand two fatigue tests for the comparative evaluation ofoccipital-cervical and occipital-cervical-thoracic spinal im-plant assemblies are defined.1.4 These test methods establish guidelines for measuringdisplacements, determining the yield load
7、, and evaluating thestiffness and strength of occipital-cervical or occipital-cervical-thoracic spinal implant assemblies.1.5 It may not be possible to test some occipital-cervical andsome occipital-cervical-thoracic spinal constructs in all testconfigurations.1.6 The values stated in SI units are t
8、o be regarded asstandard. No other units of measurement are included in thisstandard.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 an
9、d determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical Test-ingE 739 Practice for Statistical Analysis of Linear or Linear-ized Stress-Lif
10、e ( S-N) and Strain-Life (e-N) Fatigue DataE 1823 Terminology Relating to Fatigue and Fracture Test-ingF 1582 Terminology Relating to Spinal ImplantsF 1717 Test Methods for Spinal Implant Constructs in aVertebrectomy ModelF 2077 Test Methods For Intervertebral Body Fusion De-vices3. Terminology3.1 D
11、efinitionsFor definitions of terms relating to thesetest methods, see Terminologies E6, F 1582, and E 1823.3.2 Definitions of Terms Specific to This Standard:3.2.1 active length of the longitudinal element, nthestraight line distance between the centers of rotation of the testblocks.3.2.2 block mome
12、nt arm, nthe perpendicular to the ap-plied load between the insertion point of an anchor and the axisof the hinge pin.3.2.3 compressive or tensile bending stiffness (N/mm),nthe compressive or tensile bending yield force divided byelastic displacement (see the initial slope of line BC in Fig. 1).3.2.
13、4 compressive or tensile bending ultimate load (N),nthe maximum compressive or tensile force in the X-Z planeapplied to an occipital-cervical or occipital-cervical-thoracicspinal implant assembly (see the force at Point E in Fig. 1). The1These test methods are under the jurisdiction of ASTM Committe
14、e F04 onMedical and Surgical Materials and Devices and are the direct responsibility ofSubcommittee F04.25 on Spinal Devices.Current edition approved Aug. 1, 2008. Published September 2008.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at servic
15、eastm.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.ultimate load should be a function of the device and not
16、of theload cell or testing machine.3.2.5 compressive or tensile bending yield load (N), nthecompressive or tensile bending force in the X-Z plane neces-sary to produce a permanent deformation equal to 0.020 timesthe active length of the longitudinal element (see the force atPoint D in Fig. 1).3.2.6
17、coordinate system/axes, nthree orthogonal axes aredefined in Figs. 2 and 3. The anterior-posterior axis is X withpositive being anterior. The medial-lateral axis is Y with leftbeing positive when viewed posteriorly. The superior-inferioraxis is Z with superior being positive.3.2.7 displacement at 2
18、% offset yield (mm), nthe dis-placement of a construct measured via the actuator thatproduces a permanent deformation equal to 0.020 times theactive length of the longitudinal element (distance OA in Fig.1).3.2.8 elastic angular displacement (degrees), nthe angu-lar displacement at 2 % offset yield
19、(see Point A in Fig. 1)minus the 2 % offset angular displacement (see Point B in Fig.1) (that is, the distance between Point A and Point B in Fig. 1).3.2.9 elastic displacement (mm), nthe displacement at2 % offset yield (see Point A in Fig. 1) minus the 2 % offsetdisplacement (see Point B in Fig. 1)
20、. (The distance betweenPoint A and Point B in Fig. 1.)3.2.10 failure, npermanent deformation resulting fromfracture, plastic deformation, or loosening beyond the ultimatedisplacement or loosening that renders the occipital-cervical oroccipital-cervical-thoracic spinal implant assembly ineffectiveor
21、unable to adequately resist load.3.2.11 fatigue life, nthe number of loading cycles, N,ofaspecified character that the occipital-cervical or occipital-cervical-thoracic spinal implant assembly sustains before fail-ure of a specified nature occurs (see Terminology E 1823).3.2.12 hinge pin, nthe cylin
22、drical rod connecting a testblock to a side support. The superior and inferior aspects of thetest construct are each secured with a single 9.6-mm diameterpin.3.2.13 insertion point of an anchor, nthe location wherethe anchor is attached to the test block. The insertion pointsshown in Figs. 4-7 are t
23、o be adhered to, if possible. Insituations where the design of the occipital-cervical oroccipital-cervical-thoracic spinal implant assembly or themanufacturers surgical instructions for installation dictateotherwise, the attachment points may deviate from thesedimensions.3.2.14 intended method of ap
24、plication, noccipital-cervical and occipital-cervical-thoracic spinal implant assem-blies contain different types of anchors. Each type of anchorhas an intended method of application to the spine.3.2.15 intended occipital-cervical spinal location, ntheanatomic region of the spine intended for the ap
25、plication of theoccipital-cervical spinal implant assembly. Spinal implantassemblies are developed for specific spinal locations such asthe posterior occipital-cervical spine.FIG. 1 Typical Load Displacement Curve or Torque Angulation CurveF27060823.2.16 intended occipital-cervical-thoracic spinal l
26、ocation,nthe anatomic region of the spine intended for the applica-tion of the occipital-cervical-thoracic spinal implant assembly.Spinal implant assemblies are developed for specific spinallocations such as the posterior occipital-cervical-thoracicspine.3.2.17 longitudinal axis offset (mm), ndistan
27、ce in the Xdirection between the centerline of the longitudinal elementand the insertion point of the anchors on the polyacetal testblock.3.2.18 longitudinal direction, nthe initial spatial orienta-tion parallel to the longitudinal element of the occipital-cervical or occipital-cervical-thoracic spi
28、nal implant assembly.The longitudinal direction is generally in the superior-inferiordirection and therefore, generally parallel to the Z-axis.3.2.19 maximum runout load, nthe maximum load thatcan be applied to an occipital-cervical or occipital-cervical-thoracic spinal implant assembly where all of
29、 the testedconstructs have withstood 5 000 000 cycles without a failure.3.2.20 occipital-cervical spinal implant assembly, nacomplete occipital-cervical spinal implant configuration asintended for surgical use. An occipital-cervical spinal implantassembly will contain anchors, interconnections, and
30、longitu-dinal elements and may contain transverse elements (see Figs.2-7).3.2.21 occipital-cervical spinal implant construct, nacomplete occipital-cervical spinal implant assembly attached tothe appropriate test blocks.3.2.22 occipital-cervical-thoracic spinal implant assembly,na complete occipital-
31、cervical-thoracic spinal implant con-figuration as intended for surgical use. An occipital-cervical-thoracic spinal implant assembly will contain anchors, inter-connections, and longitudinal elements and may containtransverse elements (see Figs. 2-7).FIG. 2 A Standard Bilateral Construct Containing
32、Screw, Rod and ScrewF27060833.2.23 occipital-cervical-thoracic spinal implant construct,na complete occipital-cervical-thoracic spinal implant as-sembly attached to the appropriate test blocks.3.2.24 offset angular displacement at 2 degrees offset, napermanent angular displacement in the X-Y plane m
33、easured viathe actuator equal to 0.020 times the torsional aspect ratio (forexample: 1.95 for 1.70 3 0.02 3 180/pi) (see Point B in Fig.1).3.2.25 offset displacement (mm), na permanent deforma-tion measured via the actuator equal to 0.020 times the activelength of the longitudinal element (for examp
34、le: 1.52 mm for a76 mm active length of the longitudinal element) (see Point Bin Fig. 1).3.2.26 permanent deformation, nthe displacement (mm)or angular displacement (degree) of the occipital-cervical oroccipital-cervical-thoracic spinal implant construct relative tothe initial unloaded condition as
35、measured via the actuator afterthe applied load, moment, or torque has been removed.3.2.27 test block, nthe component of the test apparatus formounting the occipital-cervical or occipital-cervical-thoracicspinal implant assembly. A specific design of test block isrequired for each intended spinal lo
36、cation and intended methodof application. Figs. 5-7 describe the recommended designs forthe test blocks; however, alternate designs can be used as longas equivalent performance is demonstrated.3.2.28 test block load point, nthe location on the testblock at which the resultant load is transmitted fro
37、m the testapparatus.3.2.29 tightening torque, nthe specified torque that isapplied to the various threaded fasteners of the occipital-cervical or occipital-cervical-thoracic spinal implant assembly.3.2.30 torsional aspect ratio, nthe active length of thelongitudinal element divided by the distance f
38、rom the center ofrotation to the insertion point of an anchor on the cervical block(for example: in Fig. 2, 1.70 for a 76-mm active length, X =40mm and Y = 40/2 mm).A 5LD5Lx21 y2!1/2(1)where:L = active length of longitudinal element,D = distance to insertion point,x = x distance to insertion point,
39、andy = y distance to insertion point.3.2.31 torsional stiffness (N-m/degree), nthe yield torque(N-m) divided by elastic angular displacement (degrees) (theinitial slope of line BC in Fig. 1).3.2.32 torsional ultimate load (N-m), nthe maximumtorque in the X-Y plane applied to an occipital-cervical or
40、occipital-cervical-thoracic spinal implant assembly (the torqueFIG. 3 A Bilateral Hook, Rod, Screw, and Transverse Element ConstructF2706084at Point E in Fig. 1). The ultimate torque should be a functionof the device and not of the load cell or testing machine.3.2.33 ultimate displacement (mm), nthe
41、 displacementassociated with the ultimate load, ultimate bending load orultimate torque (the displacement at Point F in Fig. 1).3.2.34 yield displacement (distance OAFig. 6), nthedisplacement (mm) or angular displacement (deg) when anassembly has a permanent deformation equal to the offsetdisplaceme
42、nt or the offset angular displacement.3.2.35 yield torque (N-m), nthe 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).3.2.36 zero displacement intercept (mm), nthe intersec-tion of the straight line sectio
43、n of the load-displacement curveand the zero load axis (the zero displacement reference Point 0in Fig. 1).4. Summary of Test Methods4.1 Similar test methods are proposed for the mechanicalevaluation of all occipital-cervical and occipital-cervical-thoracic spinal implant assemblies (see Fig. 4).4.2
44、A vertebrectomy model is used for the evaluation ofboth occipital-cervical and occipital-cervical-thoracic systems.The spinal hardware is attached at the superior and inferioraspects to polyacetal homopolymer (polyacetal) test blocksseparated by a large gap. The polyacetal homopolymer used tomanufac
45、ture the test blocks should have a tensile breakingstrength no less than 61 MPa. The use of polyacetal test blocks(see Figs. 5-8) eliminates the effects of the variability of bonegeometry and material properties associated with cadaverictesting. Alternate designs of test blocks may be used as long a
46、sequivalent performance is demonstrated.FIG. 4 Occipital-Cervical Bilateral Construct Test Setup for Occipital Screws or BoltsF27060854.3 Three static mechanical tests and two dynamic tests willevaluate the occipital-cervical or occipital-cervical-thoracicspinal implant assemblies. The three static
47、mechanical tests arecompression bending, tensile bending, and torsion. The dy-namic tests are compression bending fatigue and torsionfatigue.4.4 A specific clinical indication generally requires a spe-cific occipital-cervical or occipital-cervical-thoracic spinal im-plant assembly. Occipital-cervica
48、l and occipital-cervical-thoracic spinal implant assemblies will be evaluated with testconfigurations that simulate the clinical requirements for theintended spinal location. The intended spinal location is theposterior surface of the occipital-cervical or occipital-cervical-thoracic spine (see Fig.
49、 4). The block moment arm for a testconfiguration depends on the intended spinal location. Theblock moment arm of the occipital-cervical or occipital-cervical-thoracic spine configuration (see Fig. 4) varies de-pending on the occipital attachment components, but should beno less than the block moment arm specified in the cervicalspine configuration. The cervical spine configuration (see Figs.6 and 7) specifies the block moment arm.4.5 The intended method of application of the occipital-cervical or occipital-cervical-thoracic spinal implant a
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