ASTM F1800-97(2003)
(Test Method)Standard Test Method for Cyclic Fatigue Testing of Metal Tibial Tray Components of Total Knee Joint Replacements
Standard Test Method for Cyclic Fatigue Testing of Metal Tibial Tray Components of Total Knee Joint Replacements
SCOPE
1.1 This test method covers a procedure for the fatigue testing of metallic tibial trays used in knee joint replacements. This standard covers the procedures for the performance of fatigue tests on metallic tibial components using a cyclic, constant-amplitude force. It applies to tibial trays which cover both the medial and lateral plateaus of the tibia. This test method may require modifications to accommodate other tibial tray designs.
1.2 This test method is intended to provide useful, consistent, and reproducible information about the fatigue performance of metallic tibial trays with one unsupported condyle.
1.3 The values stated in SI units are regarded as the standard. The inch-pound units 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: F 1800 – 97 (Reapproved 2003)
Standard Test Method for
Cyclic Fatigue Testing of Metal Tibial Tray Components of
Total Knee Joint Replacements
This standard is issued under the fixed designation F 1800; 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 3. Terminology
1.1 This test method covers a procedure for the fatigue 3.1 Definitions:
testing of metallic tibial trays used in knee joint replacements. 3.1.1 R value—The R value is the ratio of the minimum load
This test method covers the procedures for the performance of to the maximum load.
fatigue tests on metallic tibial components using a cyclic,
minimum load
R 5 (1)
constant-amplitude force. It applies to tibial trays which cover
maximum load
both the medial and lateral plateaus of the tibia. This test
3.2 Definitions of Terms Specific to This Standard:
method may require modifications to accommodate other tibial
3.2.1 anteroposterior centerline—a line that passes through
tray designs.
the center of the tibial tray, parallel to the sagittal plane and
1.2 This test method is intended to provide useful, consis-
perpendicular to the line of load application. For asymmetric
tent, and reproducible information about the fatigue perfor-
tibial tray designs, the appropriate center of the tibial tray shall
mance of metallic tibial trays with one unsupported condyle.
be determined by the investigator and the rationale reported.
1.3 The values stated in SI units are regarded as the
3.2.2 fixture centerline—a line that passes through the
standard. The inch-pound units given in parentheses are for
center of the fixture, parallel to the anteroposterior centerline.
information only.
This line represents the separation between the supported and
1.4 This standard does not purport to address all of the
unsupported portions of the test fixture.
safety concerns, if any, associated with its use. It is the
3.2.3 mediolateral centerline—a line that passes through
responsibility of the user of this standard to establish appro-
the center of the tibial tray, parallel to the coronal, or frontal,
priate safety and health practices and determine the applica-
plane and perpendicular to the line of load application. For
bility of regulatory limitations prior to use.
asymmetric tibial tray designs, the appropriate center of the
tibial tray shall be determined by the investigator and the
2. Referenced Documents
rationale reported.
2.1 ASTM Standards:
3.2.4 moment arm “d ”—the perpendicular distance be-
2 ap
E 4 Practices for Force Verification of Testing Machines
tween the mediolateral centerline of the tibia component and
E 467 Practice for Verification of Constant Amplitude Dy-
the line of load application.
namic Loads in an Axial Load Fatigue Testing System
3.2.5 moment arm “d ”—the perpendicular distance be-
ml
E 468 Practice for the Presentation of Constant Amplitude
tween the anteroposterior centerline of the tibia component and
Fatigue Results for Metallic Materials
the line of load application.
E 1150 Definitions of Terms Relating to Fatigue
4. Significance and Use
4.1 This test method can be used to describe the effects of
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 materials, manufacturing, and design variables on the fatigue
F04.22 on Arthroplasty.
performance of metallic tibial trays subject to cyclic loading
Current edition approved April 10, 2003. Published June 2003. Originally
for relatively large numbers of cycles.
approved in 1997. Last previous edition approved in 1997 as F 1800 – 97.
Annual Book of ASTM Standards, Vol 03.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F 1800 – 97 (2003)
4.2 The loading of tibial tray designs in vivo will, in general, 6.3 When the tibial tray design includes a central keel or
differ from the loading defined in this test method. The results other prominence, the proper method for support of the keel
obtained here cannot be used to directly predict in vivo
must be determined. Depending on the tibial tray design, it may
performance. However, this test method is designed to allow
be necessary to evaluate the design with or without support of
for comparisons between the fatigue performance of different
the keel (see Fig. 2). The method of supporting (or not
metallic tibial tray designs, when tested under similar condi-
supporting) any such feature shall be reported.
tions.
6.4 A spacer of plastic possessing sufficient stiffness and
4.3 In order for fatigue data on tibial trays to be comparable,
creep resistance (for example, ultra high molecular weight
reproducible, and capable of being correlated among laborato-
polyethylene, acetal co-polymer) shall be placed between the
ries, it is essential that uniform procedures be established.
tibial tray and the load applicator (see Fig. 3). The spacer shall
contain a spherical indentation (or recess) for the spherical
5. Specimen Selection
indenter. This recess shall be greater to or equal than the
5.1 The test component selected shall have the same geom-
diameter of the spherical indenter and is included to minimize
etry as the final product, and shall be in finished condition.
the chance of spacer fracture under load. The spacer shall have
a minimum thickness of 6 mm (0.25 in.), measured at the dome
6. Apparatus
of the sphere. It is recommended that the diameter of the spacer
6.1 The tibial tray shall be mounted as a cantilever beam
is 13 mm (0.5 in.).
(see Fig. 1 and Fig. 2). Care shall be taken to ensure that the
fixation of the tibial tray does not produce abnormal stress
NOTE 1—Actual dimensions of the spacer may vary as smaller tibial
concentrations that could change the failure mode of the part.
tray designs may require a smaller diameter disk.
One possible setup involving fixation of the inferior surface or
6.4.1 The spacer shall be placed on the unsupported tibial
clamping of the superior surface is shown in Fig. 1 and Fig. 2.
condyle. The purpose of the spacer is to distribute load to the
If necessary, bone cement or other high strength epoxy may be
tibial tray condyle and to eliminate possible fretting fatigue
used on the supported aspect of the tibial tray to prevent
initiated by contact between the metal indenter and the tibial
loosening during the test.
tray.
6.2 The tibial tray shall be positioned such that the antero-
posterior centerline and the fixture centerline are aligned with 6.5 The fixturing shall be constructed so that the load shall
an accuracy of 61mminthe x direction and 62° in the x–y be applied perpendicular to the undeflected superior surface of
plane (see Fig. 1 and Fig. 2). the tibial tray.
FIG. 1 Schematic of Test Setup Without a Central Keel
F 1800 – 97 (2003)
FIG. 2 Schematic or Test Setup With a Central Keel
FIG. 3 Recommended Spacer Drawing
6.6 The point of load application shall be located at a known 7.2 Analyze the action of the machine to ensure that the
distance from the anteroposterior centerline (d ) and from the desired form and periodic force amplitude is maintained for the
ml
mediolateral centerline (d ). duration of the test (see Practice E 467 or use a validated strain
ap
6.7 The load shall be applied by means of a spherical
gaged part).
indenter, a diameter of 32 mm (1.25 in.) is recommended.
7.3 The test machine shall have a load monitoring system
such as the transducer mounted in line with the specimen.
7. Equipment Characteristics
Monitor the test loads continuously in the early stages of the
test and periodically thereafter to ensure the desired load cycle
7.1 Perform the tests on a fatigue test machine with ad-
equate load capacity. is maintained. Maintain the varying load as determined by
F 1800 – 97 (2003)
suitable dynamic verification at all times to within 62 % of the 9. Test Termination
largest compressive force being used.
9.1 Continue the test until the tibial tray fails or until a
predetermined number of cycles has been applied to the
8. Procedure
implant. The suggested number of cycles is ten million. Failure
8.1 Determine the size of the tibial tray component used by
may be defined as: a fracture of the tibial tray; formation of a
the investigator. Dimensions shall be reported.
crack detectable by eye, fluorescent dye penetrant, or other
8.2 Position the test specimen such that the load axis is
non-destructive means; or exceeding a predetermined deflec-
perpendicular to the undeflected superior surface of the tray
tion limit.
since the tray surface will not remain perpendicular to the load
axis during loading.
10. Report
8.3 Mount one side of a symmetric tibial component on the
10.1 Report the fatigue test specimens, procedures
...
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