Standard Test Method for Determination of Frictional Torque and Friction Factor for Hip Implants Using an Anatomical Motion Hip Simulator

SIGNIFICANCE AND USE
5.1 This test procedure provides a method of evaluating the frictional torque and friction factor of artificial hip joint bearings under the stated in-vitro test conditions.  
5.2 Friction is not simply a materials property. The specimen system and the effects on its friction are multi-factorial, including the materials and processing of the components, the design and assembly of the components, the test parameters, and environmental factors (lubricant, temperature, etc.).  
5.3 The procedure may be used as a standardized method of measuring friction for a particular system, or as a method of investigating the effects of specific test parameters such as hip sizes, designs, radial clearance, different lubricants, clamping (nonuniform sphericity), misalignments during installation, etc.  
5.4 The procedure may be used to study the variation of friction with time as the specimens wear, which is particularly useful for samples that undergo a transition from “run-in” to “steady-state” wear behavior. Since the motion and load waveforms are identical to those specified in ISO 14242-1:2014, standardized friction and wear measurements may be combined and viewed in the correct perspective where they affect each other.  
5.5 Frictional torque, and in particular the maximum value, are useful to assess the torques that may compromise fixation, or cause disassociation of modular components in acetabular cup or liner/shell assemblies through a lever-out or torsion-out mechanism.  
5.6 Friction factor is a useful parameter for comparison of materials and designs, and provides insights into the lubrication regime operating in the implant system. Friction factor measurement may also be able to detect acetabular liner deformation (clamping referred to earlier).
SCOPE
1.1 This test procedure provides a method of evaluating the frictional torque and friction factor of artificial hip joint bearings used in Total Hip Replacement systems. The method presented here was based on a published study, first as a conference paper in 2008 (1)2 and then as a peer-reviewed journal paper (2). The method is compatible with and is capable of being carried out during actual wear testing of total hip replacement implants on wear simulators equipped with multiple degrees of freedom force and moment sensors.  
1.2 Although the methodology described does not replicate all physiological loading conditions, it is a means of in-vitro comparison of the frictional torque and friction factor of artificial hip joint bearings used in Total Hip Replacement systems under the stated test conditions.  
1.3 Units—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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

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Published
Publication Date
14-Nov-2020
Current Stage
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ASTM F3446-20 - Standard Test Method for Determination of Frictional Torque and Friction Factor for Hip Implants Using an Anatomical Motion Hip Simulator
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: F3446 − 20
Standard Test Method for
Determination of Frictional Torque and Friction Factor for
1
Hip Implants Using an Anatomical Motion Hip Simulator
This standard is issued under the fixed designation F3446; 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 2. Referenced Documents
3
2.1 ASTM Standards:
1.1 This test procedure provides a method of evaluating the
F86 Practice for Surface Preparation and Marking of Metal-
frictional torque and friction factor of artificial hip joint
lic Surgical Implants
bearings used in Total Hip Replacement systems. The method
F732 Test Method for Wear Testing of Polymeric Materials
presented here was based on a published study, first as a
2
Used in Total Joint Prostheses
conference paper in 2008 (1) and then as a peer-reviewed
F2025 Practice for Gravimetric Measurement of Polymeric
journal paper (2). The method is compatible with and is
Components for Wear Assessment
capable of being carried out during actual wear testing of total
G40 Terminology Relating to Wear and Erosion
hip replacement implants on wear simulators equipped with
4
2.2 ISO Standards:
multiple degrees of freedom force and moment sensors.
ISO 14242-1 Implants for Surgery—Wear ofTotal Hip-Joint
1.2 Although the methodology described does not replicate
Prostheses, Part 1: Loading and Displacement Parameters
all physiological loading conditions, it is a means of in-vitro
for Wear-Testing Machines and Corresponding Environ-
comparison of the frictional torque and friction factor of
mental Conditions for Test
artificial hip joint bearings used in Total Hip Replacement
ISO 14242-2 Implants for Surgery—Wear ofTotal Hip-Joint
systems under the stated test conditions.
Prostheses, Part 2: Methods of Measurement
ISO 4287 Surface Texture: Profile Method—Terms, Defini-
1.3 Units—The values stated in SI units are to be regarded
tions and Surface Texture Parameters
as standard. No other units of measurement are included in this
ISO 4288 Surface Texture: Profile Method—Rules and Pro-
standard.
cedures for the Assessment of Surface Texture
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3. Terminology
responsibility of the user of this standard to establish appro-
3.1 Definitions:
priate safety, health, and environmental practices and deter-
3.1.1 friction, n—the resisting force tangential to the com-
mine the applicability of regulatory limitations prior to use.
mon boundary between two bodies when, under the action of
1.5 This international standard was developed in accor-
an external force, one body moves or tends to move relative to
dance with internationally recognized principles on standard-
the surface of the other.
ization established in the Decision on Principles for the
3.1.2 friction coeffıcient, n—usually, friction force divided
Development of International Standards, Guides and Recom-
by the applied compressive load.
mendations issued by the World Trade Organization Technical
3.1.3 friction factor, n—in the spherical portions of articu-
Barriers to Trade (TBT) Committee.
lar surfaces, this factor is defined here for use as an effective
frictional coefficient, equal to the overall total tangential
1
This test method is under the jurisdiction ofASTM Committee F04 on Medical
3
and Surgical Materials and Devices and is the direct responsibility of Subcommittee For referenced ASTM standards, visit the ASTM website, www.astm.org, or
F04.22 on Arthroplasty. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Current edition approved Nov. 15, 2020. Published January 2021. DOI: 10.1520/ Standards volume information, refer to the standard’s Document Summary page on
F3446-20. the ASTM website.
2 4
The boldface numbers in parentheses refer to the list of references at the end of Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
this standard. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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F3446 − 20
frictionalforcesonthehipfemoralheadcomponentdividedby sizes, designs, radial clearance, different lubricants, clamping
the overall compressive load on that hip component. (nonuniform sphericity), misalignments during installation,
etc.
3.1.4 frictional torqu
...

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