This test method provides a screening test for determining the
amount of metal loss from plates and screws used for osteosynthesis
(internal fixation of broken bones) due to fretting corrosion in
the contact area between the screw head and the plate hole
countersink area. The implants are used in the form they would be
used clinically. The machine described generates a relative motion
between plates and screws which simulates one type of motion
pattern that can occur when these devices are used clinically.
Since the environmental and stress conditions used in this test
method may not be identical to those experienced by bone plates in
the human body, this test method may produce fretting corrosion
rates that are lower or higher than those experienced in practice.
The recommended axial load of 400 N was selected as being in a
range where the amount of fretting corrosion is not sensitive to
small changes in axial load (1).2 The
combination of the recommended load and angular displacement are
such that a measurable amount of fretting corrosion of surgical
alloys occurs in a comparatively short period of time (7 to 14
days). (Refs 1-3)
The device is designed so as to facilitate sterilization of the
test specimens and test chambers to permit testing with
proteinaceous solutions that would become contaminated with
microbial growth in nonsterile conditions.
The specimens used can be standard osteosynthesis implants or
can be materials fabricated into the appropriate shapes.
This test method may be used for testing the fretting corrosion
of metal plates and screws of similar or different alloy
compositions, or it may be used for testing the fretting corrosion
of metal-nonmetal combinations. This test method may also be used
for wear or degradation studies of nonmetallic materials. This test
method may be used as a screening test to rank the corrosivities of
saline or proteinaceous solutions, or to rank metal-to-metal
couples for resistance to fretting corrosion, or to study other
The values stated in either SI units or inch-pound units are to
be regarded separately as standard. The values stated in each
system may not be exact equivalents; therefore, each system shall
be used independently of the other. Combining values from the two
systems may result in non-conformance with the standard.
This standard may involve hazardous materials, operations,
and equipment. This standard does not purport to address all of the
safety concerns associated with its use. It is the responsibility
of whoever uses this standard to consult and establish appropriate
safety and health practices and determine the applicability of
regulatory limitations prior to use.
2 The boldface numbers in parentheses refer to the
list of references at the end of this standard.
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