ASTM F1820-97(2009)
(Test Method)Standard Test Method for Determining the Axial Disassembly Force of a Modular Acetabular Device
Standard Test Method for Determining the Axial Disassembly Force of a Modular Acetabular Device
SIGNIFICANCE AND USE
This test method is intended to help assess the axial locking strength of the acetabular liner in a modular shell when subjected to a tensile loading condition. Additional means of evaluating the locking mechanisms of modular acetabular devices may be appropriate depending upon the design of the device (that is, lever-out, torsional strength, fatigue, and so forth).
This test method may not be appropriate for all implant applications. The user is cautioned to consider the appropriateness of the method 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 modular acetabular devices, comparison of such data for various device designs must take into consideration the size of the implant and the type of locking mechanism evaluated. The location of the locking mechanism relative to the load application may be dependent upon the size and design of the acetabular device. In addition, the locking mechanism itself may vary with size, particularly if the design is circumferential in nature (for example, larger diameter implants would have a greater area of acetabular shell/acetabular liner interface than a small diameter implant).
SCOPE
1.1 This test method covers a standard methodology by which to measure the attachment strength between the modular acetabular shell and liner. Although the methodology described does not replicate physiological loading conditions, it has been described as a means of comparing integrity of various locking mechanisms.
1.2 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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Standards Content (Sample)
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Designation: F1820 − 97(Reapproved 2009)
Standard Test Method for
Determining the Axial Disassembly Force of a Modular
1
Acetabular Device
This standard is issued under the fixed designation F1820; 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 (for example, through bone cement, intimate press-fit, porous
ingrowth, integral screw threads, anchoring screws, pegs, and
1.1 This test method covers a standard methodology by
so forth). The acetabular shell may be either solid or contain
which to measure the attachment strength between the modular
holes for fixation, or contain a hole for instrumentation, or all
acetabular shell and liner.Although the methodology described
of these.
does not replicate physiological loading conditions, it has been
3.1.3 locking mechanism—any structure, design feature or
described as a means of comparing integrity of various locking
2
combination thereof, that provides mechanical resistance to
mechanisms.
movement between the liner and shell.
1.2 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4. Summary of Test Method
responsibility of the user of this standard to establish appro-
4.1 The axial disassembly of an acetabular device test
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. method provides a means to measure the axial locking strength
of the acetabular liner for modular acetabular devices.
2. Referenced Documents
4.2 Following proper assembly of the acetabular liner in an
3
2.1 ASTM Standards:
acetabular shell, the assembled device is attached to a fixture
E4 Practices for Force Verification of Testing Machines
such that the cup opening is facing downward. The acetabular
shell is supported and an axial force is applied to the acetabular
3. Terminology
liner until it disengages. The load required to disengage the
3.1 Definitions of Terms Specific to This Standard:
acetabular liner from the acetabular shell is recorded. The
3.1.1 acetabular liner—portion of the modular acetabular
acetabular liner should only be tested one time; however, the
device with an internal hemispherical socket intended to
acetabular shell may used more than once if no damage to the
articulate with the head of a femoral prosthesis. The external
locking mechanism has occurred.
geometryofthiscomponentinterfaceswiththeacetabularshell
through a locking mechanism which may be integral to the
5. Significance and Use
design of the liner and shell or may rely upon additional
5.1 This test method is intended to help assess the axial
components (for example, metal ring, screws, and so forth).
locking strength of the acetabular liner in a modular shell when
3.1.2 acetabular shell—the external, hollow structure (usu-
subjected to a tensile loading condition. Additional means of
ally metal) that provides additional mechanical support or
evaluating the locking mechanisms of modular acetabular
reinforcement for an acetabular liner and whose external
devices may be appropriate depending upon the design of the
features interface directly with the bones of the pelvic socket
device (that is, lever-out, torsional strength, fatigue, and so
forth).
1
This test method is under the jurisdiction ofASTM Committee F04 on Medical
5.2 This test method may not be appropriate for all implant
and Surgical Materials and Devicesand is the direct responsibility of Subcommittee
applications. The user is cautioned to consider the appropriate-
F04.22 on Arthroplasty.
ness of the method in view of the materials and design being
Current edition approved Feb. 1, 2009. Published March 2009. Originally
tested and their potential application.
approved in 1997. Last previous edition approved in 2003 as F1820 – 97(2003).
DOI: 10.1520/F1820-97R09.
5.3 While this test method may be used to measure the force
2
Tradonsky M.D., Steve, et al, “AComparison of the Disassociation Strength of
required to disengage modular acetabular devices, comparison
Modular Acetabular Components,” Clinical Orthopaedics and Related Research,
Number 296, November 1993.
of such data for various device designs must take into
3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
consideration the size of the implant and the type of locking
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
mechanism evaluated. The location of the locking mechanism
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. relative to the load application may be dependent upon
...
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