1、Designation: F 1820 97 (Reapproved 2003)Standard Test Method forDetermining the Axial Disassembly Force of a ModularAcetabular Device1This standard is issued under the fixed designation F 1820; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、 revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers a standard methodology bywhich to measure the attachment strength betw
3、een the modularacetabular shell and liner. Although the methodology describeddoes not replicate physiological loading conditions, it has beendescribed as means of comparing integrity of various lockingmechanisms.21.2 This standard does not purport to address all of thesafety concerns, if any, associ
4、ated 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 limitations prior to use.2. Referenced Documents2.1 ASTM Standards:E 4 Practices for Force Verification of Testing Machines33.
5、Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 acetabular linerportion of the modular acetabulardevice with an internal hemispherical socket intended toarticulate with the head of a femoral prosthesis. The externalgeometry of this component interfaces with the acetabular shellth
6、rough a locking mechanism which may be integral to thedesign of the liner and shell or may rely upon additionalcomponents (for example, metal ring, screws, and so forth).3.1.2 acetabular shellthe external, hollow structure (usu-ally metal) that provides additional mechanical support orreinforcement
7、for an acetabular liner and whose externalfeatures interface directly with the bones of the pelvic socket(for example, through bone cement, intimate press-fit, porousingrowth, integral screw threads, anchoring screws, pegs, andso forth). The acetabular shell may be either solid or containholes for f
8、ixation, or contain a hole for instrumentation, or allof these.3.1.3 locking mechanismany structure, design feature orcombination thereof, that provides mechanical resistance tomovement between the liner and shell.4. Summary of Test Method4.1 The axial disassembly of an acetabular device testmethod
9、provides a means to measure the axial locking strengthof the acetabular liner for modular acetabular devices.4.2 Following proper assembly of the acetabular liner in anacetabular shell, the assembled device is attached to a fixturesuch that the cup opening is facing downward. The acetabularshell is
10、supported and an axial force is applied to the acetabularliner until it disengages. The load required to disengage theacetabular liner from the acetabular shell is recorded. Theacetabular liner should only be tested one time; however, theacetabular shell may used more than once if no damage to thelo
11、cking mechanism has occurred.5. Significance and Use5.1 This test method is intended to help assess the axiallocking strength of the acetabular liner in a modular shell whensubjected to a tensile loading condition. Additional means ofevaluating the locking mechanisms of modular acetabulardevices may
12、 be appropriate depending upon the design of thedevice (that is, lever-out, torsional strength, fatigue, and soforth).5.2 This test method may not be appropriate for all implantapplications. The user is cautioned to consider the appropriate-ness of the method in view of the materials and design bein
13、gtested and their potential application.5.3 While this test method may be used to measure the forcerequired to disengage modular acetabular devices, comparisonof such data for various device designs must take intoconsideration the size of the implant and the type of lockingmechanism evaluated. The l
14、ocation of the locking mechanismrelative to the load application may be dependent upon the sizeand design of the acetabular device. In addition, the lockingmechanism itself may vary with size, particularly if the design1This test method is under the jurisdiction of ASTM Committee F04 on Medicaland S
15、urgical Materials and Devicesand is the direct responsibility of SubcommitteeF04.22on Arthroplasty.Current edition approved Apr. 10, 2003. Published June 2003. Originallyapproved in 1997. Last previous edition approved in 1997 as F 1820 97.2Tradonsky M.D., Steve, et al, “A Comparison of the Disassoc
16、iation Strength ofModular Acetabular Components,” Clinical Orthopaedics and Related Research,Number 296, November 1993.3Annual Book of ASTM Standards, Vol 03.01.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.is circumferential in na
17、ture (for example, larger diameterimplants would have a greater area of acetabular shell/acetabular liner interface than a small diameter implant).6. Apparatus6.1 An apparatus capable of supporting only the acetabularshell while allowing the acetabular liner to be freely disas-sembled from the shell
18、 is required. The fixture shall beconstructed so that the line of load application is through theapex of the shell or is perpendicular to the face center of theacetabular shell.6.2 The testing machine shall conform to the requirementsof Practices E 4. The loads used to determine the attachmentstreng
19、th shall be within the range of the testing machine asdefined in Practices E 4.6.3 The test machine should be capable of delivering acompressive or tensile force at a constant displacement rate.The test machine should have a load monitoring and recordingsystem.7. Sampling7.1 All acetabular liners sh
20、all be representative of implantquality products. This shall include any sterilization or thermalprocesses which may alter the material properties or geometry.7.2 A partially finished acetabular shell or permanent fixtureblock may be substituted for a completed acetabular shellprovided that the inte
21、rnal materials, finish, locking mechanism,and geometry are identical to the actual acetabular shell.7.3 A minimum of five shells and liners shall be tested todetermine the axial disassembly force of an acetabular device.Pairing of the acetabular shells and liners shall be at randomunless otherwise r
22、eported. The appropriateness of performingmultiple tests on the same acetabular shell will depend on thedesign of the device. The acetabular liner should only be testedone time; however, the acetabular shell may be used more thanonce if no damage has occurred to the locking mechanism.8. Procedure8.1
23、 Assemble the liner and shell according to the surgicalprocedure guidelines. Once assembled, the liner shell constructshould be placed in a fixture similar to that described in Fig. 1,that is, a fixture that will support the acetabular shell withoutdistortion while allowing axial load to be applied
24、to the liner.An axial load should be applied (coincident with the axes of theliner and shell) to the liner through a center hole in the shell ata rate of 5.1 cm/min. It may be necessary to create a hole in theshell at the apex in order to apply an axial load to the liner. Asmall diameter drill blank
25、 or plug could be used as a loadapplicator. The maximum load required to completely disen-gage the liner from the shell should be measured and recorded.8.2 Record maximum disassembly force.8.3 Testing of samples shall be terminated when one of thefollowing has occurred:8.3.1 The disengagement force
26、becomes negligible.8.3.2 Prior to disassembly, the liner suffers excessive dam-age (that is, puncture of the liner or severe liner deformation).Puncture of the liner should be considered an invalid test.9. Report9.1 Report the following information:9.1.1 The device name, size, materials, and lot num
27、ber, ifapplicable,FIG. 1 Schematic of Liner DisassemblyF 1820 97 (2003)29.1.2 Maximum force required to disengage the liner fromthe shell from each of the test samples,9.1.3 Mode of failure, and9.1.4 Specify the orientation of the liner and outer shell ifthe axes are not coincident.10. Precision and
28、 Bias10.1 No information can be presented on the precision andbias of this test method for measuring the axial disassemblyforce of modular acetabular devices, because no materialhaving an accepted reference value is available.11. Keywords11.1 acetabular component; arthroplasty; disassemblyAPPENDIX(N
29、onmandatory Information)X1. RATIONALEX1.1 The intent of this test method is to establish a meansof comparing various acetabular designs, not to set a minimumfor the disassembly force of the acetabular prosthesis. Inaddition, this test method does not specifically address thelocking mechanisms abilit
30、y to maintain its integrity withsequential assemblies and disassemblies. However, if deemedappropriate by the user, the method could be considered fordetermining the ability of the locking mechanism to resistdegradation after repeated assemblies.X1.2 Prototype designs may be used with this test meth
31、odand may be considered implant quality if the geometricaldimensions are within the tolerances of the final design andhave been subjected to any processes that may effect thegeometrical stability of the implant.X1.3 Temperature and environment may effect the lockingstrength of the acetabular design.
32、 If the these factors areconsidered, then the environment and the temperature shouldbe reported in the results.X1.4 Occasionally shells without holes may need to beevaluated. For these designs it may become necessary to drilla hole in the apex of the shell for insertion of the drill blank orplug. Ho
33、les should not be made if the locking mechanism iscompromised, and alternative methods should be considered toapply the load coincident with the acetabular liner and shellaxis.X1.5 Some designs may be susceptible to degradation inliner locking force after fatigue; therefore, consideration maybe give
34、n to the effect of fatigue on the disengagement force ofacetabular devices.4ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validit
35、y of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comment
36、s are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not
37、 received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copi
38、es) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).4Fosco, D.R., and Buchanan, D.J., “The Importance of Fatigue Loading WhenAssessing Liner/Shell Distraction Resistance and Congruency for Modular Acetabu-lar Components,” Modularity of Orthopaedic Implants, ASTM STP 1301, Donald E.Marlowe and Michael B. Mayor, Eds., ASTM, 1997.F 1820 97 (2003)3
