ASTM F1820-13

Standard Test Method for Determining the Forces for Disassembly of Modular Acetabular Devices

SIGNIFICANCE AND USE
5.1 This test method is intended to help assess the locking strength of the acetabular liner in a modular shell when subjected to three different force application conditions.  
5.2 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.  
5.3 While these test methods 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, a larger diameter implants would have a greater area of acetabular shell/acetabular liner interface than a small diameter implant).  
5.4 Material failure is possible before locking mechanism failure during either push-out or offset pullout/lever-out conditions. This is due to the possibility that the shear strength of the material may be exceeded before the locking mechanism is fully tested. If this occurs, those results shall be reported and steps taken to minimize this effect. Some possibilities for minimizing shear might include utilizing the smallest size components, using a flat rod end rather than a round rod end or placing a small metal plate between the liner and shell (during push-out). For well-designed polyethylene inserts, it may not be possible to push out or offset pullout/lever out the liner without fracture. In some cases, reporting the maximum force and acknowledging that the true disassembly force will be higher may be justified.
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 the integrity of various locking mechanisms.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 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.

General Information

• Status: Historical
• Publication Date: 31-Jan-2013
• ICS: 11.040.40 - Implants for surgery, prosthetics and orthotics
• Technical Committee: F04 - Medical and Surgical Materials and Devices
• Drafting Committee: F04.22 - Arthroplasty

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: F1820 − 13
Standard Test Method for
Determining the Forces for Disassembly of Modular
1
Acetabular Devices
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 3.1.2 acetabular shell—the external, hollow (usually metal)
structure that provides additional mechanical support or rein-
1.1 This test method covers a standard methodology by
forcement for an acetabular liner and whose external features
which to measure the attachment strength between the modular
interface directly with the bones of the pelvic socket (for
acetabular shell and liner.Although the methodology described
example, through bone cement, intimate press-fit, porous
does not replicate physiological loading conditions, it has been
ingrowth, integral screw threads, anchoring screws, pegs, and
described as a means of comparing the integrity of various
so forth). The acetabular shell may be either solid or contain
locking mechanisms.
holes for fixation, or contain a hole for instrumentation, or all
1.2 The values stated in SI units are to be regarded as
of these.
standard. No other units of measurement are included in this
3.1.3 locking mechanism—any structure, design feature or
standard.
combination thereof, that provides mechanical resistance to
1.3 This standard does not purport to address all of the
movement between the liner and shell.
safety concerns, if any, associated with its use. It is the
3.1.4 polar axis—the axis of revolution of the rotationally
responsibility of the user of this standard to establish appro-
symmetric portions of the acetabular liner or shell.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
4. Summary of Test Method
2. Referenced Documents
4.1 All acetabular liners shall be inserted into the acetabular
2
shells for testing by applying a force of 2 kN. This value is
2.1 ASTM Standards:
similar to the force required to set the head in Test Methods
E4 Practices for Force Verification of Testing Machines
F2345.
F2345 Test Methods for Determination of Static and Cyclic
Fatigue Strength of Ceramic Modular Femoral Heads
4.2 Axial Disassembly:
4.2.1 The axial disassembly of an acetabular device test
3. Terminology
method provides a means to measure the axial locking strength
of the acetabular liner for modular acetabular devices.
3.1 Definitions of Terms Specific to This Standard:
4.2.2 Following proper assembly of the acetabular liner in
3.1.1 acetabular liner—portion of the modular acetabular
an acetabular shell, the assembled device is attached to a
device with an internal hemispherical socket intended to
fixture such that the cup opening is facing downward. The
articulate with the head of a femoral prosthesis. The external
acetabular shell is supported and an axial force is applied to the
geometryofthiscomponentinterfaceswiththeacetabularshell
acetabular liner until it disengages. The force required to
through a locking mechanism which may be integral to the
disengage the acetabular liner from the acetabular shell is
design of the liner and shell or may rely upon additional
recorded.
components (for example, metal ring, screws, and so forth).
4.3 Offset Pullout or Lever Out Disassembly:
4.3.1 The offset pullout or the lever out disassembly method
1
This test method is under the jurisdiction ofASTM Committee F04 on Medical
isintendedtoassesstheresistanceofthelockingmechanismto
and Surgical Materials and Devicesand is the direct responsibility of Subcommittee
edge forces that could occur when the neck of a hip prosthesis
F04.22 on Arthroplasty.
impinges on the edge of the acetabular liner. An impinging
Current edition approved Feb. 1, 2013. Published March 2013. Originally
force could cause the edge of the acetabular liner opposite the
approved in 1997. Last previous edition approved in 2009 as F1820 – 97(2009).
DOI: 10.1520/F1820-13.
area of impinging contact to be pushed out of the shell. The
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
resistance of the acetabular liner edge to being pulled loose
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
from the shell is a measure of the resistance to impingement
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. causing loosening of the acetabular liner.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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F1820 − 13
4.3
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: F1820 − 97 (Reapproved 2009) F1820 − 13
Standard Test Method for
Determining the Axial Forces for Disassembly Force of a
1
Modular Acetabular DeviceDevices
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
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 the integrity of various locking mechanisms.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 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.
2. Referenced Documents
2
2.1 ASTM Standards:
E4 Practices for Force Verification of Testing Machines
F2345 Test Methods for Determination of Static and Cyclic Fatigue Strength of Ceramic Modular Femoral Heads
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 acetabular liner—portion of the modular acetabular device with an internal hemispherical socket intended to articulate
with the head of a femoral prosthesis. The external geometry of this component interfaces with the acetabular shell through a
locking mechanism which may be integral to the design of the liner and shell or may rely upon additional components (for
example, metal ring, screws, and so forth).
3.1.2 acetabular shell—the external, hollow structure (usually metal) structure that provides additional mechanical support or
reinforcement for an acetabular liner and whose external features interface directly with the bones of the pelvic socket (for
example, through bone cement, intimate press-fit, porous ingrowth, integral screw threads, anchoring screws, pegs, and so forth).
The acetabular shell may be either solid or contain holes for fixation, or contain a hole for instrumentation, or all of these.
3.1.3 locking mechanism—any structure, design feature or combination thereof, that provides mechanical resistance to
movement between the liner and shell.
3.1.4 polar axis—the axis of revolution of the rotationally symmetric portions of the acetabular liner or shell.
4. Summary of Test Method
4.1 The axial disassembly of an acetabular device test method provides a means to measure the axial locking strength of the
acetabular liner for modularAll acetabular liners shall be inserted into the acetabular shells for testing by applying a force of 2 kN.
This value is similar to the force required to set the head in Test Methods F2345acetabular devices.
4.2 Following proper assembly of the acetabular liner in an acetabular shell, the assembled device is attached to a fixture such
that the cup opening is facing downward. The acetabular shell is supported and an axial force is applied to the acetabular liner until
1
This test method is under the jurisdiction of ASTM Committee F04 on Medical and Surgical Materials and Devicesand is the direct responsibility of Subcommittee F04.22
on Arthroplasty.
Current edition approved Feb. 1, 2009Feb. 1, 2013. Published March 2009March 2013. Originally approved in 1997. Last previous edition approved in 20032009 as
F1820 – 97(2003).(2009). DOI: 10.1520/F1820-97R09.10.1520/F1820-13.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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F1820 − 13
it disengages. The load required to disengage the acetabular liner from the acetabular shell is recorded. The acetabular liner should
only be tested one time; however, the acetabular shell may used more than once if no damage to the locking mechanism has
occurred.Axial Disassembly:
4.2.1 The axial disassembly of an aceta
...