1、Designation:F171711a Designation: F1717 12Standard Test Methods forSpinal Implant Constructs in a Vertebrectomy Model1This standard is issued under the fixed designation F1717; 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 These test methods cover the materials and methods for the static and fatigue testing of spinal implant assembli
3、es in avertebrectomy model. The test materials for most combinations of spinal implant components can be specific, depending on theintended spinal location and intended method of application to the spine.1.2 These test methods are intended to provide a basis for the mechanical comparison among past,
4、 present, and future spinalimplant assemblies. They allow comparison of spinal implant constructs with different intended spinal locations and methods ofapplication to the spine. These test methods are not intended to define levels of performance, since sufficient knowledge is notavailable to predic
5、t the consequences of the use of a particular device.1.3 These test methods set out guidelines for load types and methods of applying loads. Methods for three static load types andone fatigue test are defined for the comparative evaluation of spinal implant assemblies.1.4 These test methods establis
6、h guidelines for measuring displacements, determining the yield load, and evaluating the stiffnessand strength of the spinal implant assembly.1.5 Some spinal constructs may not be testable in all test configurations.1.6 The values stated in SI units are to be regarded as standard. No other units of
7、measurement are included in this standard.1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
8、limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D638 Test Method for Tensile Properties of PlasticsE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE177 Practice for Use of the Terms Precision and Bias in ASTM Test Met
9、hodsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test MethodE739 Practice for Statistical Analysis of Linear or Linearized Stress-Life (S-N) and Strain-Life (-N) Fatigue DataE1150 Definitions of Terms Relating to FatigueF1582 Terminology Relating to Spinal Im
10、plantsF2077 Test Methods For Intervertebral Body Fusion Devices3. Terminology3.1 Definitions:3.1.1 For definitions of terms relating to these test methods, see Terminology E6, Terminology F1582, and Definitions E1150.3.2 Definitions of Terms Specific to This Standard:3.2.1 active length of the longi
11、tudinal elementthe straight line distance between the center of attachment of the superioranchor and the center of attachment of the inferior anchor.3.2.2 angular displacement at 2 % offset yield (degrees)the angular displacement of a construct measured via the actuator thatproduces a permanent angu
12、lar displacement in the X-Y plane equal to 0.020 times the torsional aspect ratio (see Point A in Fig.1).1These test methods are under the jurisdiction ofASTM Committee F04 on Medical and Surgical Materials and Devices and are the direct responsibility of SubcommitteeF04.25 on Spinal Devices.Current
13、 edition approved July 1, 2011.May 15, 2012. Published July 2011.June 2012. Originally approved in 1996. Last previous edition approved in 2011 as F1717 11a.DOI: 10.1520/F1717-11A.10.1520/F1717-12.2For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at
14、serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.1This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous vers
15、ion. Becauseit 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 versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM Internation
16、al, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.3 block moment armthe perpendicular to the applied load between the insertion point of an anchor and the axis of thehinge pin.3.2.4 compressive or tensile bending stiffness (N/mm)the compressive or tensile be
17、nding yield force divided by elasticdisplacement (see the initial slope of line BC in Fig. 1).3.2.5 compressive or tensile bending ultimate load (N)the maximum compressive or tensile force in the X-Z plane applied toa spinal implant assembly (see the force at Point E in Fig. 1). The ultimate load sh
18、ould be a function of the device and not of theload cell or testing machine.3.2.6 compressive or tensile bending yield load (N)the compressive or tensile bending force in the X-Z plane necessary toproduce a permanent deformation equal to 0.020 times the active length of the longitudinal element (see
19、 the force at Point D inFig. 1).3.2.7 coordinate system/axesthree orthogonal axes are defined in Fig. 2 and Fig. 3. The anterior-posterior axis is X withpositive being anterior. The medial-lateral axis is Y with left being positive when viewed posteriorly. The superior-inferior axis isZ with superio
20、r being positive.3.2.8 displacement at 2 % offset yield (mm)the displacement of a construct measured via the actuator that produces apermanent deformation equal to 0.020 times the active length of the longitudinal element (see Point A in Fig. 1).3.2.9 elastic angular displacement (degrees)the angula
21、r displacement at 2 % offset yield (see PointAin Fig. 1) minus the 2 %offset angular displacement (see Point B in Fig. 1). (The distance between Point A and Point B in Fig. 1.)3.2.10 elastic displacement (mm)the displacement at 2 % offset yield (see PointAin Fig. 1) minus the 2 % offset displacement
22、(see Point B in Fig. 1). (The distance between Point A and Point B in Fig. 1.)3.2.11 failurepermanent deformation resulting from fracture, plastic deformation, or loosening beyond the ultimatedisplacement or loosening that renders the spinal implant assembly ineffective or unable to adequately resis
23、t load.3.2.12 fatigue lifethe number of loading cycles, N, of a specified character that the spinal implant assembly sustains beforefailure of a specified nature occurs (see Definitions E1150).3.2.13 insertion point of an anchorthe location where the anchor is attached to the test block. The inserti
24、on points shown inFigs. 2-15 are to be adhered to if possible. In situations where the design of the spinal implant assembly or the manufacturerssurgical instructions for installation dictate otherwise, the attachment points may deviate from these dimensions.3.2.14 intended method of applicationspin
25、al implant assemblies contain different types of anchors. Each type of anchor hasFIG. 1 Typical Load Displacement Curve or Torque AngulationCurveF1717 122an intended method of application to the spine.3.2.15 intended spinal locationthe anatomic region of the spine intended for the application of the
26、 spinal implant assembly.Spinal implant assemblies are developed for specific spinal locations such as the anterior cervical spine or the posteriorthoracolumbar, lumbar, and lumbosacral spine.3.2.16 hinge pinthe cylindrical rod connecting a test block to a side support. A cervical construct is secur
27、ed with a 9.6 mmdiameter pin and the thoracolumbar, lumbar, and lumbosacral construct uses a 12.7 mm diameter pin.3.2.17 longitudinal directionthe initial spatial orientation parallel to the longitudinal element of the spinal implant assembly.The longitudinal direction is generally in the superior-i
28、nferior direction and, therefore, generally parallel to the z axis.3.2.18 maximum run-out loadthe maximum load that can be applied to a spinal implant assembly where all of the testedconstructs have withstood 5 000 000 cycles without a failure.3.2.19 permanent deformationthe displacement (mm) or ang
29、ular displacement (degree) of the spinal implant constructrelative to the initial unloaded condition as measured via the actuator after the applied load, moment, or torque has been removed.3.2.20 spinal implant assemblya complete spinal implant configuration as intended for surgical use. A spinal im
30、plantassembly will contain anchors, interconnections, and longitudinal elements and may contain transverse elements (see Fig. 4, Fig.6, Fig. 8, Fig. 10, Fig. 12, and Fig. 14).3.2.21 spinal implant constructa complete spinal implant assembly attached to the appropriate test blocks.FIG. 2 A Standard B
31、ilateral Construct Containing Screw, Rod and ScrewF1717 1233.2.22 test blockthe component of the test apparatus for mounting the spinal implant assembly.Aspecific design of test blockis required for each intended spinal location and intended method of application. Fig. 5, Fig. 7, Fig. 9, Fig. 11, Fi
32、g. 13, and Fig.15 describe the recommended designs for the test blocks; however, alternate designs can be used as long as equivalent performanceis demonstrated.3.2.23 test block load pointthe location on the test block at which the resultant load is transmitted from the test apparatus.3.2.24 tighten
33、ing torquethe specified torque that is applied to the various threaded fasteners of the spinal implant assembly.3.2.25 torsional aspect ratiothe active length of the longitudinal element divided by the distance from the center of rotationto the insertion point of an anchor (for example: in Fig. 2 1.
34、70 for a 76-mm active length, X =40mmandY = 40/2 mm).A 5LD5Lx21 y2!1/2(1)F1717-12_1FIG. 3 A Bilateral Hook, Rod, Screw, and Transverse Element ConstructF1717 124where:A = torsional aspect ratio,L = active length of longitudinal element,D = distance to insertion point,x = x distance to insertion poin
35、t, andy = y distance to insertion point.3.2.26 torsional stiffness (N-m/degree)the yield torque (N-m) divided by elastic angular displacement (degrees) (the initialslope of line BC in Fig. 1).3.2.27 torsional ultimate load (N-m)the maximum torque in the X-Y plane applied to a spinal implant assembly
36、 (the torqueat Point E in Fig. 1). The ultimate torque should be a function of the device and not of the load cell or testing machine.3.2.28 two percent (2 %) offset angular displacement (degrees)a permanent angular displacement in the X-Y plane measuredvia the actuator equal to 0.020 times the tors
37、ional aspect ratio (for example: 1.95 for 1.70 3 0.02 3 180/pi) (see Point B in Fig.1).3.2.29 two percent (2 %) offset displacement (mm)a permanent deformation measured via the actuator equal to 0.020 timesthe active length of the longitudinal element (for example: 1.52 mm for a 76 mm active length
38、of the longitudinal element or 0.70mm for 35 mm) (see Point B in Fig. 1).3.2.30 ultimate displacement (mm)the displacement associated with the ultimate load, ultimate bending load or ultimatetorque (the displacement at Point F in Fig. 1).3.2.31 yield torque (N-m)the torque in the X-Y plane required
39、to produce a permanent displacement of 0.020 times thetorsional aspect ratio (the torque at Point D in Fig. 1).3.2.32 zero displacement intercept (mm)the intersection of the straight line section of the load displacement curve and thezero load axis (the zero displacement reference Point 0 in Fig. 1)
40、.4. Summary of Test Methods4.1 Similar test methods are proposed for the mechanical evaluation of cervical spinal implant assemblies (see Fig. 4, Fig. 6,and Fig. 8) and thoracolumbar, lumbar, and lumbosacral spinal implant assemblies (see Fig. 10, Fig. 12, and Fig. 14).FIG. 4 Cervical Unilateral Con
41、struct Test Setup for Screws or BoltsF1717 1254.2 Testing of the spinal implant assemblies will simulate a vertebrectomy model via a large gap between two Ultra HighMolecular Weight Polyethylene (UHMWPE) test blocks. The UHMWPE used to manufacture the test blocks should have a tensilebreaking streng
42、th equal to 40 6 3 MPa (see Specification D638). The UHMWPE test blocks (see Fig. 5, Fig. 7, Fig. 9, Fig. 11,Fig. 13, and Fig. 15) will eliminate the effects of the variability of bone properties and morphometry. Alternate designs of testblocks may be used as long as equivalent performance is demons
43、trated.4.3 Three static mechanical tests and one dynamic test will evaluate the spinal implant assemblies. The three static mechanicaltests are compression bending, tensile bending, and torsion. The dynamic test is a compression bending fatigue test. It is theresponsibility of the user of this stand
44、ard to determine which test(s) is (are) most appropriate for a particular spinal implantassembly.4.4 A specific clinical indication generally requires a specific spinal implant assembly. Spinal implant assemblies will beevaluated with test configurations which simulate the clinical requirements for
45、the intended spinal location. The intended spinallocations are both anterior (see Fig. 4) and posterior (see Fig. 6 and Fig. 8) surfaces of the cervical spine or both anterior (see Fig.10) and posterior (see Fig. 12 and Fig. 14) surfaces of the thoracolumbar, lumbar, and lumbosacral spine. The block
46、 moment arm(see 6.6) for a test configuration depends on the intended spinal location. The cervical spine configuration (see Fig. 5, Fig. 7, andFig. 9) specifies one block moment arm, while a larger block moment arm (see Fig. 11, Fig. 13, and Fig. 15) is specified for thethoracolumbar, lumbar, and l
47、umbosacral spine.FIG. 5 Cervical Unilateral UHWMPE Block for Screws or BoltsF1717 1264.5 The intended method of application of the spinal implant assembly may vary for specific anatomic regions and clinicalindications. Spinal implant assemblies contain different types of anchors. Each type of anchor
48、 has an intended method ofapplication to the spine. For example, one assembly may include anterior vertebral body screws and rods (see Fig. 2), while anotherassembly may contain posterior sacral screws, hooks, rods, and transverse elements (see Fig. 3). The block moment arm of a testconfiguration wi
49、ll be independent of the intended method of application of a spinal implant assembly; therefore, the test data fordifferent intended methods of application may be compared.5. Significance and Use5.1 Spinal implants are generally composed of several components which, when connected together, form a spinal implantassembly. Spinal implant assemblies are designed to provide some stability to the spine while arthrodesis takes place. These testmethods outline standard materials and methods for the evaluation of different spinal implant assembli
