ASTM F2724-21
(Test Method)Standard Test Method for Evaluating Mobile Bearing Knee Dislocation
Standard Test Method for Evaluating Mobile Bearing Knee Dislocation
SIGNIFICANCE AND USE
4.1 This test method is designed to provide a standardized method to determine the constraint of mobile bearing knee designs with regard to spin-out and spit-out of the mobile bearing.
4.2 Similar to constraint testing of total knees (see Test Method F1223), it is important to note that the test method does not simulate the soft tissues and laxity of the knee joint, which may be key factors related to the occurrence of spin-out or spit-out.3 For instance, a patient with good soft tissue restraints will perhaps require a lower spin-out/spit-out resistance, whereas a patient with major bone loss or destroyed ligamentous structures will likely require an implant with a higher spin-out/spit-out resistance. Therefore, the results from the test should be taken into account along with the condition of the patient’s soft tissues to determine the relative safety for the device.
SCOPE
1.1 This test method is designed to provide a standardized method to determine the dislocation resistance of mobile bearing knee designs with regard to femoral component disassociation and spin-out/spit-out of the mobile bearing insert.
1.2 Although the methodology described does not replicate all physiological loading conditions, it is a means of in-vitro comparison of mobile bearing knee designs and their ability to resist dislocation of the mobile bearing from the femoral or tibial components under stated test conditions.
1.3 The test method applies only to mobile bearing total knee designs.
1.4 The values stated in SI units are regarded as standard. The values given in parentheses are mathematical conversions to inch-pound units that are provided for information only and are not considered standard.
1.5 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.
1.6 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.
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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: F2724 − 21
Standard Test Method for
1
Evaluating Mobile Bearing Knee Dislocation
This standard is issued under the fixed designation F2724; 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. Terminology
1.1 This test method is designed to provide a standardized 3.1 Definitions:
method to determine the dislocation resistance of mobile 3.1.1 bearing axis, n—the line connecting the lowest points
bearing knee designs with regard to femoral component on both the lateral and medial condyles of the superior surface
disassociation and spin-out/spit-out of the mobile bearing of the mobile bearing.
insert.
3.1.2 centerline axis, n—a line through the neutral point
perpendicular to the bearing axis and in a plane parallel to the
1.2 Although the methodology described does not replicate
plane of the flat portion of the inferior articulating surface of
all physiological loading conditions, it is a means of in-vitro
the mobile bearing at 0° posterior tibial slope.
comparison of mobile bearing knee designs and their ability to
resist dislocation of the mobile bearing from the femoral or
3.1.3 mobile bearing (insert), n—the component between
tibial components under stated test conditions.
fixed femoral and tibial knee components with an articulating
surface on both the inferior and superior sides.
1.3 The test method applies only to mobile bearing total
knee designs.
3.1.4 neutral point, n—midpoint of the bearing axis.
1.4 The values stated in SI units are regarded as standard. 3.1.5 spin-out, n—excessive rotation of the bearing compo-
The values given in parentheses are mathematical conversions nent in a rotating platform knee or multi-directional platform
to inch-pound units that are provided for information only and knee such that there is dislocation between the femoral or tibial
are not considered standard. components and the mobile bearing.
1.5 This standard does not purport to address all of the 3.1.6 spit-out, n—escape of the bearing component from
safety concerns, if any, associated with its use. It is the beneath the femoral component either anteriorly or posteriorly.
responsibility of the user of this standard to establish appro-
3.1.7 total bearing spacing, n—distancebetweenthecontact
priate safety, health, and environmental practices and deter-
points as given by Test Method F1223.
mine the applicability of regulatory limitations prior to use.
3.1.8 two-axis orthogonal load frame, n—a test machine
1.6 This international standard was developed in accor-
capable of applying forces and displacements that act at 90° to
dance with internationally recognized principles on standard-
each other.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
4. Significance and Use
mendations issued by the World Trade Organization Technical
4.1 This test method is designed to provide a standardized
Barriers to Trade (TBT) Committee.
method to determine the constraint of mobile bearing knee
2. Referenced Documents designs with regard to spin-out and spit-out of the mobile
2
bearing.
2.1 ASTM Standards:
F1223 Test Method for Determination of Total Knee Re- 4.2 Similar to constraint testing of total knees (see Test
placement Constraint
Method F1223), it is important to note that the test method
does not simulate the soft tissues and laxity of the knee joint,
which may be key factors related to the occurrence of spin-out
1
This test method is under the jurisdiction ofASTM Committee F04 on Medical
3
or spit-out. For instance, a patient with good soft tissue
and Surgical Materials and Devices and is the direct responsibility of Subcommittee
restraints will perhaps require a lower spin-out/spit-out
F04.22 on Arthroplasty.
Current edition approved March 1, 2021. Published March 2021. Originally
resistance, whereas a patient with major bone loss or destroyed
approved in 2008. Last previous edition approved in 2014 as F2724 – 08 (2014).
DOI: 10.1520/F2724-21.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
3
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Weale, A. E., et al., “In Vitro Evaluation of the Resistance to Dislocation of a
Standards volume information, refer to the standard’s Document Summary page on Meniscal-Bearing Total Knee Prosthesis Between 30° and 90° of Knee Flexion,” J.
the ASTM website. Arthroplasty, Vol 17, No. 4, 2002, pp
...
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: F2724 − 08 (Reapproved 2014) F2724 − 21
Standard Test Method for
1
Evaluating Mobile Bearing Knee Dislocation
This standard is issued under the fixed designation F2724; 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 is designed to provide a standardized method to determine the dislocation resistance of mobile-bearing
mobile bearing knee designs with regard to femoral component disassociation and spin-out/spit-out of the mobile bearing insert.
1.2 Although the methodology described does not replicate all physiological loading conditions, it is a means of in-vitro
comparison of mobile bearing knee designs and their ability to resist dislocation of the mobile bearing from the femoral or tibial
components under stated test conditions.
1.3 The test method applies only to mobile bearing total knee designs.
1.4 The values stated in SI units are regarded as standard. The values given in parentheses are mathematical conversions to
inch-pound units that are provided for information only and are not considered standard.
1.5 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.6 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.
2. Referenced Documents
2
2.1 ASTM Standards:
F1223 Test Method for Determination of Total Knee Replacement Constraint
3. Terminology
3.1 Definitions:
3.1.1 bearing axis, n—the line connecting the lowest points on both the lateral and medial condyles of the superior surface of the
mobile bearing.
3.1.2 centerline axis, n—a line through the neutral point perpendicular to the bearing axis and in a plane parallel to the plane of
the flat portion of the inferior articulating surface of the mobile bearing at 0° posterior tibial slope.
1
This test method is under the jurisdiction of ASTM Committee F04 on Medical and Surgical Materials and Devices and is the direct responsibility of Subcommittee
F04.22 on Arthroplasty.
Current edition approved March 15, 2014March 1, 2021. Published April 2014March 2021. Originally approved in 2008. Last previous edition approved in 20082014 as
F2724 – 08. 08 (2014). DOI: 10.1520/F2724-08R14.10.1520/F2724-21.
2
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 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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F2724 − 21
3.1.3 mobile bearing (insert), n—the component between fixed femoral and tibial knee components with an articulating surface
on both the inferior and superior sides.
3.1.4 neutral point, n—midpoint of the bearing axis.
3.1.5 spin-out, n—excessive rotation of the bearing component in a rotating platform knee or multi-directional platform knee such
that there is dislocation between the femoral or tibial components and the mobile bearing.
3.1.6 spit-out, n—escape of the bearing component from beneath the femoral component either anteriorly or posteriorly.
3.1.7 total bearing spacing, n—distance between the contact points as given by Test Method F1223.
3.1.8 2-axistwo-axis orthogonal load frame, n—a test machine capable of applying forces and displacements that act at 90° to each
other.
4. Significance and Use
4.1 This test method is designed to provide a standardized method to determine the constraint of mobile-bearing mobile bearing
knee designs with regardsregard to spin-out and spit-out of the mobile bearing.
4.2 Similar to constraint testing of total knees (see Test Method F1223), it is important to note that the test method does not
3
simulate the soft tissues and laxity of the knee joint, which ma
...
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