ASTM F2009-00
(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
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.
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
Standard Test Method for
Determining the Axial Disassembly Force of Taper
Connections of Modular Prostheses
This standard is issued under the fixed designation F 2009; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope this type of connection are the modular shoulder and modular
hip prostheses. Additional means of evaluating the locking
1.1 This test method establishes a standard methodology for
mechanisms of tapers may be appropriate, depending upon the
determining the force required, under laboratory conditions, to
design of the device.
disassemble tapers of implants that are otherwise not intended
4.2 This test method may not be appropriate for all implant
to release. Some examples are the femoral components of a
applications. The user is cautioned to consider the appropriate-
total or partial hip replacement or shoulder in which the head
ness of the practice in view of the materials and design being
and base component are secured together by a self-locking
tested and their potential application.
taper.
4.3 While this practice may be used to measure the force
1.2 This test method has been developed primarily for
required to disengage tapers, any comparison of such data for
evaluation of metal and ceramic head designs on metal tapers
various component designs must take into consideration the
but may have application to other materials and designs.
size of the implant and the type of locking mechanism
1.3 This standard does not purport to address all of the
evaluated.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
5. Apparatus
priate safety and health practices and determine the applica-
5.1 The cone portion of the assembly shall be constrained
bility of regulatory limitations prior to use.
by suitable fixtures that can sustain high loads.
2. Referenced Documents 5.2 The fixtures shall be constructed so that the line of load
application is aligned with the axes of the male and female
2.1 ASTM Standards:
taper components within 61°.
E 4 Practices for Force Verification of Testing Machines
5.2.1 For example, modular heads may be assembled by a
F 1636 Specification for Bores and Cones for Modular
3 solid metal 100° cone as shown in Fig. 1. The cone should
Femoral Heads
provide line contact around the diameter of the head.
3. Summary of Test Method 5.2.2 For example, modular heads may be disassembled
with a metal cage that surrounds the head and provides even
3.1 The axial disassembly test method provides a means to
contact around the inferior edge of the head as shown in Fig. 2.
measure the axial locking strength of the taper connection for
5.3 The testing machine shall conform to the requirements
modular prostheses.
of Practices E 4. The loads used to determine the attachment
3.2 Following assembly, an axial tensile force is applied to
strength shall be within the range of the testing machine as
disassemble the taper connection and the maximum force is
defined in Practices E 4.
recorded.
5.4 The test machine should be capable of delivering a
4. Significance and Use
compressive and tensile force at a constant displacement rate.
The test machine should have a load monitoring and recording
4.1 This test method helps to assess the axial locking force
system.
of a modular taper. Examples of these devices are described in
Specification F 1636. Some types of devices that may utilize
6. Sampling and Test Specimens
6.1 The male and female taper components can be finished
This test method is under the jurisdiction ofASTM Committee F04 on Medical
implants or they can be simplified test specimens. The test
and Surgical Materials and Devices and is the direct responsibility of Subcommittee
specimens must have tapers manufactured to the specifications
F04.22 on Arthroplasty.
of a finished implant including material and preferably manu-
Current edition approved March 10, 2000. Published May 2000.
factured with the same equipment.
Annual Book of ASTM Standards, Vol 03.01.
Annual Book of ASTM Standards, Vol 13.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F2009–00
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, con-
centricity, surface roughness, taper angle, and length of en-
gagement.
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 6 1°; the load may be applied using a constant
displacement rate until the maximum load (2 kN) is achieved.
FIG. 1 Modular Head Assembly
A suggested displacement rate is 0.05 mm/s.
7.3.2 DropWeightAssemblyMethod—The two components
may be assembled with an impact load, that is, a 907-g weight
dropped from a 254-mm height.
7.4 Disassembly Procedure—The taper assembly should be
placed in appropriate
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