1、Designation: F 2009 00 (Reapproved 2005)Standard Test Method forDetermining the Axial Disassembly Force of TaperConnections of Modular Prostheses1This standard is issued under the fixed designation F 2009; the number immediately following the designation indicates the year oforiginal adoption or, in
2、 the case of 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 establishes a standard methodology fordetermining the force requi
3、red, under laboratory conditions, todisassemble tapers of implants that are otherwise not intendedto release. Some examples are the femoral components of atotal or partial hip replacement or shoulder in which the headand base component are secured together by a self-lockingtaper.1.2 This test method
4、 has been developed primarily forevaluation of metal and ceramic head designs on metal tapersbut may have application to other materials and designs.1.3 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 s
5、tandard 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:2E4 Practices for Force Verification of Testing MachinesF 1636 Specification for Bores and Cones for ModularFemoral Heads33.
6、 Summary of Test Method3.1 The axial disassembly test method provides a means tomeasure the axial locking strength of the taper connection formodular prostheses.3.2 Following assembly, an axial tensile force is applied todisassemble the taper connection and the maximum force isrecorded.4. Significan
7、ce and Use4.1 This test method helps to assess the axial locking forceof a modular taper. Examples of these devices are described inSpecification F 1636. Some types of devices that may utilizethis type of connection are the modular shoulder and modularhip prostheses. Additional means of evaluating t
8、he lockingmechanisms of tapers may be appropriate, depending upon thedesign of the device.4.2 This test method may not be appropriate for all implantapplications. The user is cautioned to consider the appropriate-ness of the practice in view of the materials and design beingtested and their potentia
9、l application.4.3 While this practice may be used to measure the forcerequired to disengage tapers, any comparison of such data forvarious component designs must take into consideration thesize of the implant and the type of locking mechanismevaluated.5. Apparatus5.1 The cone portion of the assembly
10、 shall be constrainedby suitable fixtures that can sustain high loads.5.2 The fixtures shall be constructed so that the line of loadapplication is aligned with the axes of the male and femaletaper components within 61.5.2.1 For example, modular heads may be assembled by asolid metal 100 cone as show
11、n in Fig. 1. The cone shouldprovide line contact around the diameter of the head.5.2.2 For example, modular heads may be disassembledwith a metal cage that surrounds the head and provides evencontact around the inferior edge of the head as shown in Fig. 2.5.3 The testing machine shall conform to the
12、 requirementsof Practices E4. The loads used to determine the attachmentstrength shall be within the range of the testing machine asdefined in Practices E4.1This test method is under the jurisdiction of ASTM Committee F04 on Medicaland Surgical Materials and Devices and is the direct responsibility
13、of SubcommitteeF04.22 on Arthroplasty.Current edition approved Oct. 1, 2005. Published October 2005. Originallyapproved in 2000. Last previous edition approved in 2000 as F 2009 00.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.or
14、g. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.4 The test machine should be capable of delivering a
15、compressive and tensile force at a constant displacement rate.The test machine should have a load monitoring and recordingsystem.6. Sampling and Test Specimens6.1 The male and female taper components can be finishedimplants or they can be simplified test specimens. The testspecimens must have tapers
16、 manufactured to the specificationsof a finished implant including material and preferably manu-factured with the same equipment.6.2 The supporting material around the female taper must besimilar in size and shape to the finished implant.6.3 A minimum of five taper assemblies shall be tested todeter
17、mine the axial disassembly force between the taperedcomponents. Pairing of the components shall be random unlessotherwise reported. The appropriateness of performing mul-tiple tests on the same taper connection will depend on thedesign and application of the device.6.4 Sterilization of test componen
18、ts is not required unless ithas known effects on the parts being evaluated. Generally,sterilization does not have an effect on metallic materials.7. Procedure7.1 Following normal laboratory cleaning procedures toremove any debris or other surface contaminants, the tapercomponents are assembled on a
19、suitable test machine. Asuggested procedure for cleaning and drying of the specimensis given in Appendix X1.7.2 Each specimen should be characterized prior to testing.This information may include, but is not limited to thefollowing: material, hardness, bore and taper diameters, con-centricity, surfa
20、ce roughness, taper angle, and length of en-gagement.7.3 Tapers can be assembled using two methods. Dependingon the intended use, the user may use the assembly method thatbest suits the taper application.7.3.1 Constant Rate Assembly MethodA 2 kN peak staticload is applied to the taper component alon
21、g the long axis ofthe taper within 6 1; the load may be applied using a constantdisplacement rate until the maximum load (2 kN) is achieved.A suggested displacement rate is 0.05 mm/s.7.3.2 Drop Weight Assembly MethodThe two componentsmay be assembled with an impact load, that is, a 907-g weightdropp
22、ed from a 254-mm height.7.4 Disassembly ProcedureThe taper assembly should beplaced in appropriate fixtures in a qualified test machine. Thefixture should be capable of maintaining the load axis angle towithin 61. Special care should be taken to ensure that noartificial hoop stresses or bending mome
23、nts are placed on thetaper assembly while disassembling the tapers. A displacementrate of 0.05 mm/s may be used. The load and displacementshould be recorded continuously until the test is terminated.7.5 Testing of each specimen shall be terminated when thedisassembly load drops by at least 90 % of t
24、he peak load.8. Report8.1 The test report shall include the following:8.1.1 The device name, materials, assembly method, loadversus displacement graph, sample size, and manufacturer andlot number, if applicable. Additional information pertaining tothe drop weight method is desirable and may include,
25、 but is notlimited to the following: description of the drop weightapparatus, drop weight mass, drop height.FIG. 1 Modular Head AssemblyFIG. 2 Modular Head DisassemblyF 2009 00 (2005)28.1.2 Maximum load required to disassemble the tapers.8.1.3 The displacement rate if the constant rate method isused
26、.8.1.4 Additional information characterizing each test speci-men prior to testing is desirable to better interpret the testresults. This information may include, but is not limited to thefollowing: material, hardness, bore and taper diameters, con-centricity, surface roughness, taper angle, and leng
27、th of en-gagement.9. Precision and Bias9.1 No information can be presented on the precision andbias of this test method for measuring the axial disassemblyforce of tapers because no material having an acceptedreference value is available.10. Keywords10.1 arthroplasty; disassembly; heads; hip prosthe
28、sis;modular; shoulder prosthesis; tapersAPPENDIXES(Nonmandatory Information)X1. METHOD FOR CLEANING SPECIMENSX1.1 Rinse with tap water to remove bulk contaminants.X1.2 Wash in ultrasonic cleaner in a solution of 1 %detergent for 15 min.X1.3 Rinse in a stream of diluted water.X1.4 Rinse in an ultraso
29、nic cleaner of distilled water for 5min.X1.5 Rinse in a stream of distilled water.X1.6 Allow to air dry at room temperature.X2. RATIONALEX2.1 It is not the intent of this method to specificallyaddress the locking mechanisms ability to maintain its integ-rity with sequential assemblies and disassembl
30、ies. If deemedappropriate by the user, the method could be considered fordetermining the ability of the locking mechanism to resistdegradation after repeated assemblies.X2.2 Modular femoral heads have been used in variousTHR designs since approximately 1970. This concept providesfeatures to suit the
31、 patient as planned preoperatively, orselected intraoperatively by the surgeon such as componentmaterial, neck length, and head diameter, or both.X2.3 Modular heads typically are installed in surgery usingmanual impact loads; however, because there can be largevariations due to individual strength,
32、impact rate, hammermass, off-axis loading, soft tissue damping, etc., and becauseimpact and dissociation forces are directly related4,5a repeat-able assembly method is recommended in order to comparedissociation forces.X2.3.1 Other assembly methods, however, could be desir-able. Two other methods ha
33、ve been discussed: the dropped-weight impact method and manufacturers recommendation.Some manufacturers may provide a tool that delivers therecommended force to assemble the modular components.These methods could be justified, but because of the potentialvariation in assembly loads and limited acces
34、s to instruments,these methods are not recommended within the scope of thistest method. For the instances that necessitate these assemblymethods, proper documentation detailing the procedure shouldbe required.X2.4 An aspect of modular junction integrity to considermay be the affect of fatigue. Fatig
35、ue is known to affect themechanical stability of materials and components that fittogether. It may be necessary to determine the post fatiguedisengagement force of modular junctions.4Loch, K.A. Gleason, R.F. Kyle, and J.E. Bechtold, “Axial Pull-Off Strength ofDry and Wet Taper Head Connections on a
36、Modular Shoulder Prosthesis,” TransOrthopaedic Research Society, p. 826, 1994.5Blevens, X. Deng, P.A. Torzilli, D. Dines, and R.F. Warren, “Disassociation ofModular Humeral Head Components: A Biomechanical and Implant RetrievalStudy,” Shoulder and Elbow Surgery, Vol 6, No. 2, p. 113124.F 2009 00 (20
37、05)3ASTM 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 validity of any such patent rights, and the riskof infringement of such rights,
38、 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 comments are invited either for revision of this standard or for additional sta
39、ndardsand 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 received a fair hearing you shouldmake your views known to the ASTM Com
40、mittee 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 copies) 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).F 2009 00 (2005)4
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