ASTM F2580-07
(Test Method)Standard Test Method for Evaluation of Modular Connection of Proximally Fixed Femoral Hip Prosthesis
Standard Test Method for Evaluation of Modular Connection of Proximally Fixed Femoral Hip Prosthesis
SIGNIFICANCE AND USE
This test method can be used to describe the effects of materials, manufacturing, and design variables on the fatigue performance of metallic femoral hip prostheses subject to cyclic loading for large numbers of cycles.
The loading of femoral hip designs in vivo will, in general, differ from the loading defined in this test method. The results obtained here cannot be used to directly predict in vivo performance. However, this test method is designed to allow for comparisons between the fatigue performance of different metallic femoral hip designs, when tested under similar conditions.
In order for fatigue data on femoral hip prostheses to be comparable, reproducible, and capable of being correlated among laboratories, it is essential that uniform procedures be established.
SCOPE
1.1 This test method covers a procedure for the fatigue testing of metallic femoral hip prostheses used in hip joint replacements. This test method covers the procedures for the performance of fatigue tests on metallic femoral hip stems using a cyclic, constant-amplitude force. It applies to hip prostheses that utilize proximal metaphyseal fixation and are of a modular construct, and it is intended to evaluate the fatigue performance of the modular connections in the metaphyseal filling (that is, proximal body) region of the stem.
1.2 This test method is intended to provide useful, consistent, and reproducible information about the fatigue performance of metallic hip prostheses while held in a proximally fixated manner, with the distal end not held by a potting medium.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:F2580–07
Standard Test Method for
Evaluation of Modular Connection of Proximally Fixed
Femoral Hip Prosthesis
This standard is issued under the fixed designation F 2580; 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 ISO 7206–4 Determination of Endurance Properties of
Stemmed Femoral Components with Application of Tor-
1.1 This test method covers a procedure for the fatigue
sion
testing of metallic femoral hip prostheses used in hip joint
replacements. This test method covers the procedures for the
3. Terminology
performance of fatigue tests on metallic femoral hip stems
3.1 Definitions:
using a cyclic, constant-amplitude force. It applies to hip
3.1.1 R value, n—The R value is the ratio of the minimum
prosthesesthatutilizeproximalmetaphysealfixationandareof
load to the maximum load.
a modular construct, and it is intended to evaluate the fatigue
minimum load
performance of the modular connections in the metaphyseal
R 5
maximum load
filling (that is, proximal body) region of the stem.
1.2 This test method is intended to provide useful, consis-
3.2 Definitions of Terms Specific to This Standard:
tent, and reproducible information about the fatigue perfor-
3.2.1 extraction—removal of the femoral hip implant from
mance of metallic hip prostheses while held in a proximally
the femur during surgery.
fixated manner, with the distal end not held by a potting
3.2.2 extractor hole—a hole in the proximal body of the
medium.
stem in which an apparatus is placed to remove the implant
1.3 The values stated in SI units are to be regarded as the
from the femur.
standard. The values given in parentheses are for information
3.2.3 femoral head—convex spherical bearing member for
only.
articulation with the natural acetabulum or prosthetic acetabu-
1.4 This standard does not purport to address all of the
lum.
safety concerns, if any, associated with its use. It is the
3.2.4 femoral head offset—the perpendicular distance from
responsibility of the user of this standard to establish appro-
the centerline of the implant stem to the center of the femoral
priate safety and health practices and determine the applica-
head.
bility of regulatory limitations prior to use.
3.2.5 frontal plane—the plane that lies in the medial-lateral
direction of the implant. Adduction occurs in this plane.
2. Referenced Documents
3.2.6 implant centerline—the axis that runs vertically from
2.1 ASTM Standards:
the proximal body of the implant, down the center of the stem
E 467 Practice for Verification of Constant Amplitude Dy-
to the distal end.
namic Forces in an Axial Fatigue Testing System
3.2.7 pivot axis—the center of rotation of the pivot fixture
E 468 Practice for Presentation of Constant Amplitude Fa-
(andprosthesispottedwithinit)withinthetestfixturesetup;its
tigue Test Results for Metallic Materials
location is determined by the intersection of the neck and stem
E 1150 Definitions of Terms Relating to Fatigue
centerlines of the prothesis (Figs. 1 and 2).
2.2 ISO Standards:
3.2.8 pivot fixture—the fixture in which the specimen is
potted, and is attached to the main test fixture; characterized by
1 two pins on the side that serve as the pivot axis.
This test method is under the jurisdiction ofASTM Committee F04 on Medical
3.2.9 rotational plane—the plane that lies perpendicular to
and Surgical Materials and Devices and is the direct responsibility of Subcommittee
F04.22 on Arthroplasty.
the stem axis of the implant.
Current edition approved June 15, 2007. Published July 2007.
3.2.10 sagittal plane—the plane that lies perpendicular to
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
the Frontal plane; flexion occurs in this plane.
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.
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
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.
F2580–07
4. Significance and Use
4.1 This test method can be used to describe the effects of
materials, manufacturing, and design variables on the fatigue
performance of metallic femoral hip prostheses subject to
cyclic loading for large numbers of cycles.
4.2 The loading of femoral hip designs in vivo will, in
general,differfromtheloadingdefinedinthistestmethod.The
results obtained here cannot be used to directly predict in vivo
performance. However, this test method is designed to allow
for comparisons between the fatigue performance of different
metallic femoral hip designs, when tested under similar con-
ditions.
4.3 In order for fatigue data on femoral hip prostheses to be
comparable, reproducible, and capable of being correlated
among laboratories, it is essential that uniform procedures be
established.
5. Specimen Selection
5.1 The test component selected shall have the same geom-
FIG. 1 Free Body Diagram of Test Setup
etry as the final product, and shall be in finished condition.The
test component shall be of the worst-case size and configura-
tion (that is, the component that produces the highest stresses)
of the implant family to be tested.
5.2 The femoral head component selected for load applica-
tion shall be of the same design and material as a current
product in use, but may be previously tested.
5.3 The femoral head selected shall offer the greatest load
offset from the hip centerline, to represent a worst-case
bending scenario during testing.
6. Apparatus
6.1 The hip implant may be tested in different orientations
to better reproduce specific testing conditions that are being
evaluated. For example: An anatomical orientation of 9°
flexion, and 10° adduction (per ISO 7206-4), or vertically in
both planes. The criteria used to determine the orientation
should be reported.
6.2 Care shall be taken to ensure that the fixation of the
implant does not produce abnormal stress concentrations that
could change the failure mode of the part.
6.3 Afixed-bearing load applicator shall be used to keep the
specimen aligned in the chosen orientation during testing, as
well as a fixture that allows the stem to bend during testing,
such as a u-joint.
6.4 The fixture used to hold the implant during testing
should have a reaction bolt that will oppose the loading on the
femoral head, keeping the implant in equilibrium.The position
ofthereactionboltshouldbeadjustabletoaccommodatestems
of different lengths and design features.
6.5 The fixtures and aligning materials used should be of a
design that positions the implant, when potted, so that: the
point defined by the intersection of the neck and stem center-
lines is coincident with the pivot axis (Fig. 1), the stem is fixed
vertically in both medial/lateral and anterior/posterior direc-
tions, the stem is aligned facing forward in the rotational plane
(that is, the frontal plane is normal to the pivot axis of the
fixture),(Fig.3)andthatanymatingsurfacesbetweenmodular
FIG. 2 Schematic Representation of the Test Set-up
components of the specimen do not come in contact with the
potting medium.
F2580–07
resistance to cracking or crumbling during fatigue. Examples
of different potting media include bone cement, dental acrylic,
or a low melting point alloy. The type and manufacturer of the
potting material chosen should be reported.
8.2.4 Pour the potting material into the pivot fixture, around
the specimen. If necessary, use another material such as tape or
clay to block any gaps to prevent the material from seeping
through to any area outside the pivot fixture. Care should be
taken to ensure that potting medium does not come in contact
with any mating surfaces on the proximal component.
8.2.5 The proximal potting level shall be at the proximal
surface of the proximal body component (see Figs. 1 and 2).
No potting material should enter any space between modular
components of the specimen.
8.2.6 Allow the material to cure completely before continu-
ing.
8.3 Specimen Assembly and Impaction:
NOTE—Once assembled, the pivot axis will be coincident with the point 8.3.1 Remove all secondary fixtures used to align the
ontheimplantdefinedbytheintersectionoftheneckandstemcenterlines.
implant in the pivot fixture.
FIG. 3 Proximal Sleeve Component Potted in Pivot Fixture
8.3.2 Clean the internal and distal surfaces of the proximal
component with acetone to remove any potting or other
material that came into contact with the surface. Avoid allow-
7. Equipment Characteristics
ing the acetone to contact the good potting material.
7.1 Perform the tests on a fatigue test machine with ad-
8.3.3 Assemble the remainder of the implant, ensuring that
equate load capacity.
the stem remains aligned properly in all planes of
...
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