ASTM F2009-00(2011)
(Test Method)Standard Test Method for Determining the Axial Disassembly Force of Taper Connections of Modular Prostheses
Standard Test Method for Determining the Axial Disassembly Force of Taper Connections of Modular Prostheses
SIGNIFICANCE AND USE
This test method helps to assess the axial locking force of a modular taper. Examples of these devices are described in Specification . Some types of devices that may utilize this type of connection are the modular shoulder and modular hip prostheses. Additional means of evaluating the locking mechanisms of tapers may be appropriate, depending upon the design of the device.
This test method may not be appropriate for all implant applications. The user is cautioned to consider the appropriateness of the practice in view of the materials and design being tested and their potential application.
While this test method may be used to measure the force required to disengage tapers, any comparison of such data for various component designs must take into consideration the size of the implant and the type of locking mechanism evaluated.
SCOPE
1.1 This test method establishes a standard methodology for determining the force required, under laboratory conditions, to disassemble tapers of implants that are otherwise not intended to release. Some examples are the femoral components of a total or partial hip replacement or shoulder in which the head and base component are secured together by a self-locking taper.
1.2 This test method has been developed primarily for evaluation of metal and ceramic head designs on metal tapers but may have application to other materials and designs.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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 appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: F2009 − 00 (Reapproved 2011)
Standard Test Method for
Determining the Axial Disassembly Force of Taper
Connections of Modular Prostheses
This standard is issued under the fixed designation F2009; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.2 Following assembly, an axial tensile force is applied to
disassemble the taper connection and the maximum force is
1.1 This test method establishes a standard methodology for
recorded.
determining the force required, under laboratory conditions, to
disassemble tapers of implants that are otherwise not intended
4. Significance and Use
to release. Some examples are the femoral components of a
4.1 This test method helps to assess the axial locking force
total or partial hip replacement or shoulder in which the head
of a modular taper. Examples of these devices are described in
and base component are secured together by a self-locking
Specification F1636. Some types of devices that may utilize
taper.
this type of connection are the modular shoulder and modular
1.2 This test method has been developed primarily for
hip prostheses. Additional means of evaluating the locking
evaluation of metal and ceramic head designs on metal tapers
mechanisms of tapers may be appropriate, depending upon the
but may have application to other materials and designs.
design of the device.
1.3 The values stated in SI units are to be regarded as 4.2 This test method may not be appropriate for all implant
standard. No other units of measurement are included in this applications. The user is cautioned to consider the appropriate-
standard. ness of the practice in view of the materials and design being
tested and their potential application.
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the 4.3 Whilethistestmethodmaybeusedtomeasuretheforce
responsibility of the user of this standard to establish appro- required to disengage tapers, any comparison of such data for
priate safety and health practices and determine the applica- various component designs must take into consideration the
bility of regulatory limitations prior to use. size of the implant and the type of locking mechanism
evaluated.
2. Referenced Documents
5. Apparatus
2.1 ASTM Standards:
5.1 The cone portion of the assembly shall be constrained
E4 Practices for Force Verification of Testing Machines
by suitable fixtures that can sustain high loads.
F1636 SpecificationforBoresandConesforModularFemo-
5.2 The fixtures shall be constructed so that the line of load
ral Heads (Withdrawn 2001)
application is aligned with the axes of the male and female
3. Summary of Test Method
taper components within 61°.
5.2.1 For example, modular heads may be assembled by a
3.1 The axial disassembly test method provides a means to
solid metal 100° cone as shown in Fig. 1. The cone should
measure the axial locking strength of the taper connection for
provide line contact around the diameter of the head.
modular prostheses.
5.2.2 For example, modular heads may be disassembled
with a metal cage that surrounds the head and provides even
This test method is under the jurisdiction ofASTM Committee F04 on Medical
contact around the inferior edge of the head as shown in Fig. 2.
and Surgical Materials and Devices and is the direct responsibility of Subcommittee
5.3 The testing machine shall conform to the requirements
F04.22 on Arthroplasty.
Current edition approved March 1, 2011. Published April 2011. Originally of Practices E4. The loads used to determine the attachment
approved in 2000. Last previous edition approved in 2005 as F2009 – 00 (2005).
strength shall be within the range of the testing machine as
DOI: 10.1520/F2009-00R11.
defined in Practices E4.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
5.4 The test machine should be capable of delivering a
Standards volume information, refer to the standard’s Document Summary page on
compressive and tensile force at a constant displacement rate.
the ASTM website.
The test machine should have a load monitoring and recording
The last approved version of this historical standard is referenced on
www.astm.org. system.
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F2009 − 00 (2011)
of a finished implant, including material, and preferably
manufactured with the same equipment.
6.2 Thesupportingmaterialaroundthefemaletapershallbe
similar in size and shape to the finished implant.
6.3 A minimum of five taper assemblies shall be tested to
determine the axial disassembly force between the tapered
components. Pairing of the components shall be random unless
otherwise reported. The appropriateness of performing mul-
tiple tests on the same taper connection will depend on the
design and application of the device.
6.4 Sterilization of test components is not required unless it
has known effects on the parts being evaluated. Generally,
sterilization does not have an effect on metallic materials.
7. Procedure
7.1 Following normal laboratory cleaning procedures to
remove any debris or other surface contaminants, the taper
components are assembled on a suitable test machine. A
suggested procedure for cleaning and drying of the specimens
is given in Appendix X1.
7.2 Each specimen should be characterized prior to testing.
This information may include, but is not limited to, the
following: material, hardness, bore and taper diameters,
concentricity, surface roughness, taper angle, and length of
FIG. 1 Modular Head Assembly engagement.
7.3 Tapers can be assembled using two methods. Depending
ontheintendeduse,theusermayusetheassemblymethodthat
best suits the taper application.
7.3.1 Constant Rate Assembly Method—A 2 kN peak static
load is applied to the taper component along the long axis of
the taper within 61°; the load may be applied using a constant
displacement rate until the maximum load (2 kN) is achieved.
A suggested displacement rate is
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