ASTM F1875-98
(Practice)Standard Practice for Fretting Corrosion Testing of Modular Implant Interfaces: Hip Femoral Head-bore and Cone Taper Interface
Standard Practice for Fretting Corrosion Testing of Modular Implant Interfaces: Hip Femoral Head-bore and Cone Taper Interface
SCOPE
1.1 This practice describes the testing, analytical, and characterization methods for evaluating the mechanical stability of the bore and cone interface of the head and stem junction of modular hip implants subjected to cyclic loading by measurements of fretting corrosion. (1-5) Two test methods described are as follows:
1.1.1 Method I-The primary purpose of this method is to provide a uniform set of guidelines for long-term testing to determine the amount of damage by measurement of the production of corrosion products and particulate debris from fretting and fretting corrosion. Damage also is assessed by characterization of the damage to the bore and cone surfaces. (4,5)
1.1.2 Methods II-This method provides for short-term electrochemical evaluation of the fretting corrosion of the modular interface. It is not the intent of this method to produce damage nor particulate debris but rather to provide a rapid method for qualitative assessment of design changes which do not include material changes. (1-4)
1.2 This practice does not provide for judgment or prediction of in vivo implant performance, but rather, provides for a uniform set of guidelines for evaluating relative differences in performance between differing implant designs, constructs, or materials with performance defined in the context of the amount of fretting and fretting corrosion. Also, this practice should permit direct comparison of fretting corrosion data between independent research groups, and thus, provide for building of a data base on modular implant performance.
1.3 This practice provides for comparative testing of manufactured hip femoral heads and stems and for coupon type specimen testing where the male taper portion of the modular junction does not include the entire hip implant, with the taper portion of the coupon identical in design, manufacturing, and materials to the taper of the final hip implant. (4,5)
1.4 Method I of this practice has been provided in a manner to permit simultaneous evaluation of the fatigue strength of a femoral hip stem (in accordance with Practice F1440) and the mechanical stability and debris generated by fretting and fretting corrosion of the modular interface.
1.5 The general concepts and methodologies described in this practice could be applied to the study of other modular interfaces in total joint prostheses.
1.6 This standard may involve hazardous materials, operations, and equipment. 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 1875 – 98
Standard Practice for
Fretting Corrosion Testing of Modular Implant Interfaces:
Hip Femoral Head-Bore and Cone Taper Interface
This standard is issued under the fixed designation F 1875; 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 mechanical stability and debris generated by fretting and
fretting corrosion of the modular interface.
1.1 This practice describes the testing, analytical, and char-
1.5 The general concepts and methodologies described in
acterization methods for evaluating the mechanical stability of
this practice could be applied to the study of other modular
the bore and cone interface of the head and stem junction of
interfaces in total joint prostheses.
modular hip implants subjected to cyclic loading by measure-
1.6 This standard may involve hazardous materials, opera-
ments of fretting corrosion. (1-5) Two test methods described
tions, and equipment. This standard does not purport to
are as follows:
address all of the safety concerns, if any, associated with its
1.1.1 Method I—The primary purpose of this method is to
use. It is the responsibility of the user of this standard to
provide a uniform set of guidelines for long-term testing to
establish appropriate safety and health practices and deter-
determine the amount of damage by measurement of the
mine the applicability of regulatory limitations prior to use.
production of corrosion products and particulate debris from
fretting and fretting corrosion. Damage also is assessed by
2. Referenced Documents
characterization of the damage to the bore and cone sur-
2.1 ASTM Standards:
faces.(4, 5)
E 4 Practices for Force Verification of Testing Machines
1.1.2 Methods II—This method provides for short-term
E 466 Practice for Conducting Force Controlled Constant
electrochemical evaluation of the fretting corrosion of the
Amplitude Axial Fatigue Tests of Metallic Materials
modular interface. It is not the intent of this method to produce
E 467 Practice for Verification of Constant Amplitude Dy-
damage nor particulate debris but rather to provide a rapid
namic Loads in an Axial Load Fatigue Testing Machine
method for qualitative assessment of design changes which do
F 561 Practice for Retrieval and Analysis of Implanted
not include material changes.(1-4)
Medical Devices and Associated Tissues
1.2 This practice does not provide for judgment or predic-
F 746 Test Method for Pitting or Crevice Corrosion of
tion of in vivo implant performance, but rather, provides for a
Metallic Surgical Implant Materials
uniform set of guidelines for evaluating relative differences in
F 897 Test Method for Measuring Fretting Corrosion of
performance between differing implant designs, constructs, or
Osteosynthesis Plates and Screws
materials with performance defined in the context of the
F 1440 Practice for Cyclic Fatigue Testing of Metallic
amount of fretting and fretting corrosion. Also, this practice
Stemmed Hip Arthroplasty Femoral Components Without
should permit direct comparison of fretting corrosion data
Torsion
between independent research groups, and thus, provide for
F 1636 Specification for Bores and Cones for Modular
building of a data base on modular implant performance.
Femoral Heads
1.3 This practice provides for comparative testing of manu-
G 3 Practice for Conventions Applicable to Electrochemical
factured hip femoral heads and stems and for coupon type
Measurements in Corrosion Testing
specimen testing where the male taper portion of the modular
G 5 Reference Test Method for Making Potentiostatic and
junction does not include the entire hip implant, with the taper
Potentiodynamic Anodic Polarization Measurements
portion of the coupon identical in design, manufacturing, and
G 15 Terminology Relating to Corrosion and Corrosion
materials to the taper of the final hip implant.(4,5)
Testing
1.4 Method I of this practice has been provided in a manner
G 40 Terminology Relating to Wear and Erosion
to permit simultaneous evaluation of the fatigue strength of a
G 61 Test Method for Conducting Cyclic Potentiodynamic
femoral hip stem (in accordance with Practice F 1440) and the
1 2
This practice is under the jurisdiction of ASTM Committee F04 on Medical and Annual Book of ASTM Standards, Vol 03.01.
Surgical Materials and Devices and is the direct responsibility of Subcommittee Annual Book of ASTM Standards, Vol 13.01.
F04.15 on Material Test Methods. Discontinued; See 2000 Annual Book of ASTM Standards, Vol 13.01.
Current edition approved April 10, 1998. Published June 1998. Annual Book of ASTM Standards, Vol 03.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F1875–98
Polarization Measurements for Localized Corrosion Sus- of testing, the isolated fluid is withdrawn for chemical analysis
ceptibility of Iron-, Nickel-, or Cobalt-Based Alloys for total elemental level, and characterization of particulate
G 102 Practice for Calculation of Corrosion Rates and debris. The taper interface is subsequently disengaged and the
Related Information from Electrochemical Measurements surfaces inspected for fretting wear and corrosion using optical
2.2 ISO Standards: microscopy and scanning electron microscopy. The output of
ISO 7206-7 Endurance Performance of Stemmed Femoral these methods is a quantitative measure of total elemental level
6,7
Components Without Application of Torsion and a qualitative evaluation of damage of the modular interface
caused by fretting wear and corrosion.
3. Terminology
4.2 Method II—A coupon similar to that used in Method I,
or an entire femoral stem and head construct may be mounted
3.1 Definitions:
in an inverted position in a test chamber. The chamber is filled
3.1.1 corrosive wear, n—wear in which chemical or elec-
with an electrolyte solution to a level sufficient to submerge the
trochemical reaction with the environment is significant.
bore and cone interface, and a small portion of the exposed
3.1.2 coverage, n—the length, parallel to the taper surface,
neck. The area of contact and articulation between the ball and
that the bore and cone interfaces are in contact.
the test apparatus is isolated from the electrolyte, either by
3.1.3 crevice corrosion, n—localized corrosion of a metal
being above the fill level, or with an elastomeric seal used to
surface at, or immediately adjacent to, an area that is shielded
isolate the bottom of the test chamber.
from full exposure to the environment because of close
4.2.1 Procedure A— A saturated calomel electrode with a
proximity between the metal and the surface of another
luggin probe is used as a reference electrode to measure
material.
changes in the corrosion potential with an electrometer. A
3.1.4 external circuit, n—the wires, connectors, measuring
counter electrode also may be employed and the polarization
devices, current sources, etc., that are used to bring about or
characteristics measured with a potentiostat.
measure the desired electrical conditions within the test cell.
4.2.2 Procedure B— A large surface area counter electrode
3.1.5 femoral head neck extension, n—a distance parallel to
is immersed in the solution to simulate the area of the stem. A
the taper axis, from the nominal neck offset length ( k)as
zero resistance ammeter is connected between the test device
defined in Specification F 1636, and the center of the head.
and the counter electrode. The difference in current, thus
Such variants from the nominal length are used to adjust for
measured prior to and during cyclic loading represents the
resection level, leg length, and so forth. A positive neck
fretting corrosion current flowing between the modular inter-
extension equates to the center of the head being located
face (anode) and the metal sheet (cathode).
further away from the stem.
3.1.6 fretting, n—small amplitude oscillatory motion, usu-
5. Significance and Use
ally tangential, between two solid surfaces in contact.
5.1 The modular interfaces of total joint prostheses are
3.1.7 fretting corrosion, n—the deterioration at the interface
subjected to micromotion that could result in fretting and
between contacting surfaces as the result of corrosion and
corrosion. The release of corrosion products and particulate
slight oscillatory slip between the two surfaces.
debris could stimulate adverse biological reactions, as well as
3.1.8 fretting wear, n—wear arising as a result of fretting.
lead to accelerated wear at the articulation interface. Methods
3.1.9 total elemental level, n—the total weight of particulate
to assess the stability and corrosion resistance of the modular
matter and corrosion ions generated by fretting wear and
interfaces, therefore, are an essential component of device
fretting corrosion. Most analytical techniques are unable to
testing.
accurately differentiate between ions and particulates, and
5.2 Long-term in vitro testing is essential to produce dam-
therefore, total elemental level refers to all matter and corro-
age and debris from fretting of a modular interface. (4,5) The
sion products released by fretting wear and corrosion.
use of proteinaceous solutions is recommended to best simulate
3.1.10 wear, n—damage to a solid surface, generally in-
the in vivo environment.
volving progressive loss of material, due to relative motion
5.3 Short-term tests often can be useful in evaluations of
between that surface and a contacting substance or substances.
differences in design during device development.(1-4) The
electrochemical methods provide semiquantitative measures of
4. Summary of Test Method
fretting corrosion rates. The relative contributions of mechani-
4.1 Method I—The femoral stem and head components, or
cal and electrochemical processes to the total corrosion and
coupons to simulate head-taper-neck geometry, are loaded
particulate release phenomena, however, have not been estab-
cyclically in a manner similar to that described in Practice
lished; therefore, these tests should not be utilized to compare
F 1440. The head neck junction is exposed to a saline or
the effects of changes in material combinations, but rather be
proteinaceous solution, either by immersion of the entire
utilized to evaluate design changes of bore (head) and cone
device, or with a fluid containing envelope. The cyclic load is
(stem) components.
applied for a minimum of 10 million cycles. At the conclusion
5.4 These tests are recommended for evaluating the fretting
wear and corrosion of modular interfaces of hip femoral head
and stem components. Similar methods may be applied to other
Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
modular interfaces where fretting corrosion is of concern.
4th Floor, New York, NY 10036.
5.5 These methods are recommended for comparative
The bold face numbers in parentheses refers to the list of references at the end
of this standard. evaluation of the fretting wear and corrosion of new materials,
F1875–98
coatings, or designs, or a combination thereof, under consid-
eration for hip femoral head and neck modular interfaces.
Components for testing may be those of a manufactured
modular hip device (finished product) or sample coupons,
which are designed and manufactured for simulation of the
head, taper, and neck region of a modular hip device.
6. Apparatus
6.1 Testing Machines— The action of the machine should
be analyzed to ensure that the desired form and periodic force
amplitude is maintained for the duration of the test (see
Practice E 467). The test machine should have a load monitor-
ing system, such as the transducer mounted in line with the
specimen. The loads should be monitored continuously in the
early stages of the test and periodically thereafter to ensure the
desired load cycle is maintained. The varying load as deter-
mined by suitable dynamic verification should be maintained at
all times to within 62 % of the maximum force being used in
accordance with Practices E 4 and E 466.
NOTE 1—The cathode sheet surrounds, but does not make contact with
6.2 Specimen Mounting Devices, Method I—Modular hip
the device being tested. For Procedure A, the counter electrode is not
and stem components shall be set-up as described in Practices utilized, and is substituted with a luggin probe and calomel electrode.
F 1440. Coupon samples shall be set-up as shown in Fig. 1. FIG. 2 Suggested Set Up for Method II Procedure B,
Measurements of Fretting Corrosion Currents of a Complete THR
The set-up must provide for identical loading geometry as that
in Practice F 1440.
6.3 Specimen Mounting Devices, Method II—Modular hip
method may not produce as much fretting corrosion as full prosthesis
and stem components shall be set-up in an inverted position, as
exposure, due to the reduced surface area of the cathodic metal exposed.
shown in Fig. 2. Coupon samples may be set up as shown in
6.5 Environmental Chamber, Method II—The chamber shall
Fig. 1, or in an inverted orientation.
be filled with electrolyte so as to submerge the modular
6.4 Environmental Containment, Method I—The prosthesis
interface. An elastomeric seal is used to isolate the contact area
may be placed in an environmental chamber, which is filled
between the head and the load application surface. Similar
with the appropriate fluid. Care should be taken to ensure that
seals should be employed for coupon sample testing. For
the contact area between the head and the low friction thrust
coupons orientated shown in Fig. 1, the chamber fill level shall
bearing is not exposed to the electrolyte solution. The modular
be kept below the articulation between the head and the loading
interface of the prostheses or coupon samples also may be
apparatus.
enclosed in an elastomeric sleeve, which contains the electro-
6.6 Counter and Reference Electrodes, Method II—A
lyte. The materials used for such isolation must be nonreactive
counter electrode is included in the external circuit of Method
and capable of retaining the fluid environment, (that is, prevent
II to act as a cathode for measurement of corrosion currents. A
leakage), throughout the course of testing. The volume of the
reference electrode is employed for measurement of the
chamber shall be between 5 and 100 mL.
corrosion potential of the specimen.
NOTE 1—The use of small fluid volumes with the sleeve containment
6.6.1 Method II, Procedure A—The counter electrode and
saturated calomel electrode (SCE) shall be employed in a
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