ASTM F564-10(2015)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:F564 −10 (Reapproved 2015)
Standard Specification and Test Methods for
Metallic Bone Staples
ThisstandardisissuedunderthefixeddesignationF564;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope E122 Practice for Calculating Sample Size to Estimate,With
Specified Precision, the Average for a Characteristic of a
1.1 This specification covers characterization of the design
Lot or Process
and mechanical function of metallic staples used in the internal
E467 Practice for Verification of Constant Amplitude Dy-
fixation of the muscular skeletal system. It is not the intention
namic Forces in an Axial Fatigue Testing System
of this specification to describe or specify specific designs for
F75 Specification for Cobalt-28 Chromium-6 Molybdenum
metallic bone staples.
Alloy Castings and Casting Alloy for Surgical Implants
1.2 This specification includes the following four test meth-
(UNS R30075)
ods for measuring mechanical properties of metallic bone
F86 Practice for Surface Preparation and Marking of Metal-
staples:
lic Surgical Implants
1.2.1 Test Method for ConstantAmplitude Bending Fatigue
F382 SpecificationandTestMethodforMetallicBonePlates
Tests of Metallic Bone Staples—Annex A1.
F565 Practice for Care and Handling of Orthopedic Implants
1.2.2 Test Method for Pull-Out Fixation Strength of Metal-
and Instruments
lic Bone Staples—Annex A2.
F601 Practice for Fluorescent Penetrant Inspection of Me-
1.2.3 Test Method for Soft Tissue Fixation Strength of
tallic Surgical Implants
Metallic Bone Staples—Annex A3.
1.2.4 Test Method for Elastic Static Bending of Metallic F629 Practice for Radiography of Cast Metallic Surgical
Bone Staples—Annex A4. Implants
1.3 The values stated in SI units are to be regarded as
3. Finish
standard. No other units of measurement are included in this
standard.
3.1 Staples conforming to this specification shall be finished
1.4 This standard does not purport to address all of the and identified in accordance with Practice F86, as appropriate.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
4. Inspection Practices
priate safety and health practices and determine the applica-
4.1 Staples made in accordance with Specification F75
bility of regulatory limitations prior to use.
should be inspected in accordance with Practice F601 or
2. Referenced Documents
X-rayed in accordance with Practice F629.
2.1 ASTM Standards:
5. Care and Handling
E4 Practices for Force Verification of Testing Machines
5.1 Staples should be cared for and handled in accordance
This specification is under the jurisdiction of ASTM Committee F04 on
with Practice F565, as appropriate.
Medical and Surgical Materials and Devices and is the direct responsibility of
Subcommittee F04.21 on Osteosynthesis.
Current edition approved March 1, 2015. Published April 2015. Originally
6. Keywords
approved in 1985. Last previous edition approved in 2010 as F564 – 10. DOI:
10.1520/F0564-10R15. 6.1 bendingtest;bonefixation;fatiguetest;fixationdevices;
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
metallic bone staples; orthopaedic medical devices; pullout
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
test; soft tissue fixation; surgical implants
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
F564−10 (2015)
ANNEXES
(Mandatory Information)
A1. TEST METHOD FOR CONSTANT AMPLITUDE BENDING FATIGUE TESTS OF METALLIC BONE STAPLES
A1.1. Scope theapplicationofbendingfatigueloads.Thelegsofeachstaple
are fitted into fixation holes in each block with minimal
A1.1.1 This test method covers procedures for the perfor-
clearance to restrict bending of the staple within the hole. The
mance of constant amplitude fatigue testing of metallic staples
staple is fixed securely in the block using a moldable filling or
used in internal fixation of the musculoskeletal system. This
grouting agent. The extension design should minimize the
test method may be used when testing in air at ambient
weight to reduce the influence on the staple while maintaining
temperature or in an aqueous or physiological solution.
sufficient stiffness to transfer the load to the staple without
A1.1.2 The values stated in SI units are to be regarded as
undesirable deflection. Holes for pin and clevis fixation are
standard. No other units of measurement are included in this
optional (see Figs. A1.1-A1.3).
standard.
NOTE A1.1—Variations in fixation hole configuration may be required
A1.1.3 This standard does not purport to address all of the
for staple legs with noncircular cross sections. Also, it is necessary to
safety concerns, if any, associated with its use. It is the
provide a gap between the underside of the staple bridge and edge of the
staple extender in most cases. This is necessary to eliminate contact
responsibility of the user of this standard to establish appro-
between the staple bridge (or other bridge features such as tissue spikes)
priate safety and health practices and determine the applica-
and the staple extender. However, this gap should be standardized within
bility of regulatory limitations prior to use.
any test group as required.
A1.2. Summary of Test Method
A1.4.2.2 4-Point Bend Fixture—A standard or modified
bending fixture that produces pure bending in the staple
A1.2.1 Metallic bone staples are tested under bending loads
withoutappreciableshearortorsionwhenusedtoapplyloadto
until the specimen fails or a predetermined number of cycles
the staple through the staple extensions.
has been applied to it. Bending tests may be performed in one
A1.4.2.3 Pin and Clevice Fixture—A standard or modified
of two modes: either pure, in-plane bending; or tension (or
fixture used to apply a distractive or compressive load to the
compression) combined with in-plane bending. Tests using
staple through the staple extensions to produce bending in the
either of these methods may be conducted at ambient condi-
staple similar to that seen in vivo.
tions or in aqueous or physiological solutions (at either room
temperature or 37°C).
A1.4.3 Filling or Grouting Agent—A stiff, moldable filler,
suchasepoxy,acryliccement,oralow-meltingpointalloy(for
A1.3. Significance and Use
example,Wood’smetal)usedtosecurethestaplelegwithinthe
A1.3.1 This test method is used to determine the fatigue
staple extension.
resistance of metallic bone staples when subjected to repetitive
loading for large numbers of cycles.This information may also
be useful for comparing the effect of variations in staple
material, geometry, surface condition, or placement under
certain circumstances.
A1.3.2 It is essential that uniform fatigue practices be
established in order that such basic fatigue data be comparable
and reproducible and can be correlated among laboratories.
A1.3.3 The results of fatigue tests are suitable for direct
application to design only when the service conditions parallel
the test conditions exactly. This test method may not be
appropriate for all types of bone staple applications. The user
is cautioned to consider the appropriateness of the test method
in view of the materials being tested and their potential
application.
A1.4. Apparatus
A1.4.1 Testing Machines,conformingtotherequirementsof
Practices E4 and E467. The loads used for determining
strengths shall be within the loading range of the testing
machine as defined in Practices E4 and E467.
A1.4.2 Gripping Devices:
A1.4.2.1 Staple Extensions—Pairs of specially designed
metal blocks that permit the holding of individual staples for FIG. A1.14-Point Bending of Staples in Extension
F564−10 (2015)
tissue or other material to bone. All test samples shall be
representative of the material under evaluation. Samples for
comparative tests shall be produced from the same material lot
or batch and under the same fabricating conditions, unless
noted specifically.
A1.5.2 Staple Leg—The parallel or nearly parallel exten-
sions that are intended to penetrate the bone tissue; these may
be round, square, or polygonal in cross section, and they may
possess serrations or barbs to increase the fixation or purchase
strength in the bone.
A1.5.3 Staple Bridge—The cross member of the staple
connecting the legs; the bridge may be smooth or possess
spikes or projections on the underside for the retention of soft
tissue or other material.
A1.6. Procedure
A1.6.1 Mounting the Specimen—Fix the staple leg in an
extensionblockusingthefillingagent.Afixtureshouldbeused
to ensure proper in-plane alignment of the two extensions and
the staple during this process.Also, each staple should be fixed
such that the bridge is the same distance from the top of each
extension.
NOTE A1.2—This distance is at the discretion of the operator, but it
determines the portion of the staple subjected to the bending loads.
FIG. A1.2Combined Tension (or Compression) and Bending of
A1.6.2 4-Point Bend Testing:
Staples
A1.6.2.1 Place the staple and attached staple extensions in
the 4-point bending fixture such that the loading point and
support rollers contact the staple extensions on either side of
the staple; direct contact of the rollers with the staple shall not
be permitted during the test. Alignment of the loading point
rollers shall be symmetric on the centerline between the
support rollers (see Fig. A1.1).
A1.6.2.2 Apply cyclic loads (sinusoidal, sawtooth, and so
forth), generating bending moments in the staple without
permanent deformation. Appropriate starting loads should be
50 to 75 % of the static bending strength, unless indicated
otherwise.
NOTE A1.3—It may be necessary to provide a low-friction means of
maintaining the position of the staple and attached extensions. Also, the
fixtures should be designed so that loads are applied equally at the loading
points during each deflection throughout the test.
A1.6.2.3 Compute the bending moment, M, by the follow-
FIG. A1.3Diagram of Extender-Staple Forces Under Combined
ing formula, where F = force applied at each loading point and
Bending and Tension
A = distance between the loading point and support roller,
M = FA.
bending
A1.4.4 Aqueous Solution—Tap water, distilled water, physi- A1.6.2.4 Continue the test until failure of the staple, the
ological saline, or similar aqueous solutions, used to immerse fixation, or a predetermined number of load cycles has been
the test specimens fully during the test. applied.
A1.4.5 Constant Temperature Bath—An aqueous bath ca- A1.6.3 Combined Tension or (Compression) and Bending:
pable of maintaining the samples and containers at physiologic
A1.6.3.1 Place the staple and attached staple extensions in
temperatures, 37 6 2°C, for the specified testing periods.
the axial bending fixture. The pins and clevices should permit
free rotation of the staple extensions, with minimal friction,
A1.5. Test Specimen
whilemaintainingalignmentofthestaplelegs(andextensions)
in the same plane (see Fig. A1.2).
A1.5.1 Staple—A generally U-shaped metal loop, with at
least two legs, that is driven into the surface of bone to either A1.6.3.2 Apply cyclic loads (sinusoidal, sawtooth, and so
fix or immobilize adjacent pieces of bone or to fasten soft forth), generating bending moments in the staple without
F564−10 (2015)
permanent deformation. Appropriate starting loads should be A1.8. Report
50 to 75 % of the static yield strength, unless indicated
A1.8.1 Report the following information:
otherwise.
A1.8.1.1 Staple Description—Type, size, special features
(barbs, spikes, and so forth), manufacturer, material, batch or
NOTE A1.4—It may be necessary to maintain a minimum tensile or
compressive load on the specimen throughout the test, since operating at
lot number, and dimensions (including leg length, bridge
or near zero load may result in either loss of machine control due to
width, and length), as appropriate.
discontinuity in the load feedback loop or undesirable transient loading of
A1.8.1.2 Test Type—4-point or combined tension (or com-
the staple.
pression) and bending.
A1.6.3.3 Compute the bending moment in the staple bridge,
A1.8.1.3 Fixation Geometry—Load point separation dis-
M, by the following formula, where F = force applied at each
tances (4-point bending), load offset distance (combined ten-
center of each pin and L = distance between the load applica-
sion and bending), staple bridge-extension distance, and so
tion axis, that is, the pin center, and the neutral axis of the
forth.
staple bridge, M = FL (see Fig. A1.3).
bending
A1.8.1.4 Minimum and maximum cycle loads, test fre-
NOTE A1.5—The application of this test method produces bending, quency(forexample,cycles/s),andforcingfunctiontype(sine,
tensile(orcompressive),andshearstressesinthestaple.Thedirectionand
ramp, saw tooth, and so forth).
magnitudes of these stresses should be analyzed using superposition
A1.8.1.5 Bending moment, M (N-m).
theory or other suitable methods.
A1.8.1.6 Load ratio, R, where R = minimum load/maximum
A1.6.3.4 Continue the test until failure of the staple or the
load.
fixation or a predetermined number of load cycles has been
A1.8.1.7 Test Environment—Ambient air or physiological
applied.
solution.
A1.8.1.8 Number of cycles at failure or test termination
A1.6.4 Stress Verification—It is recommended that strain
(runout).
gages(orextensometry)beusedtomeasurethebendingstrains
A1.8.1.9 Location of fatigue fracture (if applicable).
induced in the specimen. This is accomplished most easily on
A1.8.1.10 Reason for test termination, that is, staple failure,
thestaplebridge,butitmaybepossibletoperformonaportion
fixation failure, runout to specified cycle limit, and so forth.
of the staple leg or at the leg-bridge junction under certain
circumstances and with certain staple designs. The recom-
A1.9. Precision
mended technique is to strain gage the actual fatigue test
A1.9.1 Intralaboratory and interlaboratory reproducibility
specimens, if possible, provided that the installation of strain
have not been determined systematically.
gage will not influence the test results.
A1.7 Test Termination A1.10 Rationale (Nonmandatory Information)
A1.7.1 Continue the tests until the specimen fails or a A1.10.1 Thistestmethodisintendedtoaidincharacterizing
predetermined number of cycles has been applied to the the fatigue behavior of metalli
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