ASTM F564-02(2006)
(Specification)Standard Specification and Test Methods for Metallic Bone Staples
Standard Specification and Test Methods for Metallic Bone Staples
ABSTRACT
This specification covers characterization of the design and mechanical function of metallic staples used in the internal fixation of the muscular skeletal system. It is not the intention of this specification to describe or specify specific designs for metallic bone staples. Different test methods shall be performed in order to determine the following mechanical properties of metallic bone staples: bending fatigue, pull-out fixation strength, soft tissue fixation strength, and elastic static bending.
SCOPE
1.1 This specification covers characterization of the design and mechanical function of metallic staples used in the internal fixation of the muscular skeletal system. It is not the intention of this specification to describe or specify specific designs for metallic bone staples.
1.2 This specification includes the following four test methods for measuring mechanical properties of metallic bone staples:
1.2.1 Test Method for Constant Amplitude Bending Fatigue Tests of Metallic Bone Staples—Annex A1.
1.2.2 Test Method for Pull-Out Fixation Strength of Metallic Bone Staples—Annex A2.
1.2.3 Test Method for Soft Tissue Fixation Strength of Metallic Bone Staples—Annex A3.
1.2.4 Test Method for Elastic Static Bending of Metallic Bone Staples—Annex A4.
1.3 Unless otherwise indicated, the values stated in SI units are to be regarded as standard. The values given in parentheses are given 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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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: F 564 – 02 (Reapproved 2006)
Standard Specification and Test Methods for
Metallic Bone Staples
This standard is issued under the fixed designation F 564; 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 E 122 Practice for Calculating Sample Size to Estimate,
With a Specified Tolerable Error, the Average for a
1.1 This specification covers characterization of the design
Characteristic of a Lot or Process
and mechanical function of metallic staples used in the internal
E 467 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 Me-
staples:
tallic Surgical Implants
1.2.1 Test Method for ConstantAmplitude Bending Fatigue
F 382 Specification and Test Method for Metallic Bone
Tests of Metallic Bone Staples—Annex A1.
Plates
1.2.2 Test Method for Pull-Out Fixation Strength of Metal-
F 565 Practice for Care and Handling of Orthopedic Im-
lic Bone Staples—Annex A2.
plants and Instruments
1.2.3 Test Method for Soft Tissue Fixation Strength of
F 601 Practice for Fluorescent Penetrant Inspection of Me-
Metallic Bone Staples—Annex A3.
tallic Surgical Implants
1.2.4 Test Method for Elastic Static Bending of Metallic
F 629 Practice for Radiography of Cast Metallic Surgical
Bone Staples—Annex A4.
Implants
1.3 Unless otherwise indicated, the values stated in SI units
are to be regarded as standard.The values given in parentheses
3. Finish
are given for information only.
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 PracticeF86, 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 F 601 or
X-rayed in accordance with Practice F 629.
2. Referenced Documents
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
with Practice F 565, as appropriate.
This specification is under the jurisdiction of ASTM Committee F04 on
Medical and Surgical Materials and Devices and is the direct responsibility of
6. Keywords
Subcommittee F04.21 on Osteosynthesis.
6.1 bendingtest;bonefixation;fatiguetest;fixationdevices;
Current edition approved March 1, 2006. Published April 2006. Originally
approved in 1985. Last previous edition approved in 2002 as F 564 – 02. metallic bone staples; orthopaedic medical devices; pullout
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
test; soft tissue fixation; surgical implants
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F 564 – 02 (2006)
ANNEXES
(Mandatory Information)
A1. TEST METHOD FOR CONSTANT AMPLITUDE BENDING FATIGUE TESTS OF METALLIC BONE STAPLES
A1.1 Scope clearance to restrict bending of the staple within the hole. The
staple is fixed securely in the block using a moldable filling or
A1.1.1 This test method covers procedures for the perfor-
grouting agent. The extension design should minimize the
mance of constant amplitude fatigue testing of metallic staples
weight to reduce the influence on the staple while maintaining
used in internal fixation of the musculoskeletal system. This
sufficient stiffness to transfer the load to the staple without
test method may be used when testing in air at ambient
undesirable deflection. Holes for pin and clevis fixation are
temperature or in an aqueous or physiological solution.
optional (see Figs. A1.1-A1.3).
A1.1.2 ThevaluesstatedinSIunitsaretoberegardedasthe
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
provide a gap between the underside of the staple bridge and edge of the
safety concerns, if any, associated with its use. It is 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.
A1.4.2.2 4-Point Bend Fixture—A standard or modified
A1.2 Summary of Test Method
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
A1.4.3 Filling or Grouting Agent—A stiff, moldable filler,
temperature or 37°C).
suchasepoxy,acryliccement,oralow-meltingpointalloy(for
example,Wood’smetal)usedtosecurethestaplelegwithinthe
A1.3 Significance and Use
staple extension.
A1.3.1 This test method is used to determine the fatigue
A1.4.4 Aqueous Solution—Tapwater,distilledwater,physi-
resistance of metallic bone staples when subjected to repetitive
ological saline, or similar aqueous solutions, used to immerse
loading for large numbers of cycles.This information may also
the test specimens fully during the test.
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 E 467. The loads used for determining
strengths shall be within the loading range of the testing
machine as defined in PracticesE4 and E 467.
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
theapplicationofbendingfatigueloads.Thelegsofeachstaple
are fitted into fixation holes in each block with minimal FIG. A1.1 4-Point Bending of Staples in Extension
F 564 – 02 (2006)
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.
A1.6.2 4-Point Bend Testing:
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
FIG. A1.2 Combined Tension (or Compression) and Bending of
Staples
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-
ing formula, where F = force applied at each loading point and
A = distance between the loading point and support roller,
M = FA.
bending
A1.6.2.4 Continue the test until failure of the staple or the
FIG. A1.3 Diagram of Extender-Staple Forces Under Combined fixation or a predetermined number of load cycles has been
Bending and Tension
applied.
A1.6.3 Combined Tension or (Compression) and Bending:
A1.4.5 Constant Temperature Bath—An aqueous bath ca-
A1.6.3.1 Place the staple and attached staple extensions in
pable of maintaining the samples and containers at physiologic
the axial bending fixture. The pins and clevices should permit
temperatures, 37 6 2°C, for the specified testing periods.
free rotation of the staple extensions, with minimal friction,
whilemaintainingalignmentofthestaplelegs(andextensions)
A1.5 Test Specimen
in the same plane (see Fig. A1.2).
A1.5.1 Staple—A generally U-shaped metal loop, with at
A1.6.3.2 Apply cyclic loads (sinusoidal, sawtooth, and so
least two legs, that is driven into the surface of bone to either
forth), generating bending moments in the staple without
fix or immobilize adjacent pieces of bone or to fasten soft
permanent deformation. Appropriate starting loads should be
tissue or other material to bone. All test samples shall be
50 to 75 % of the static yield strength, unless indicated
representative of the material under evaluation. Samples for
otherwise.
comparative tests shall be produced from the same material lot
or batch and under the same fabricating conditions, unless
NOTE A1.4—It may be necessary to maintain a minimum tensile or
noted specifically. compressive load on the specimen throughout the test, since operating at
F 564 – 02 (2006)
or near zero load may result in either loss of machine control due to
A1.8.1.1 Staple Description—Type, size, special features
discontinuity in the load feedback loop or undesirable transient loading of
(barbs, spikes, and so forth), manufacturer, material, batch or
the staple.
lot number, and dimensions (including leg length, bridge
A1.6.3.3 Compute the bending moment in the staple bridge,
width, and length), as appropriate.
M, by the following formula, where F = force applied at each A1.8.1.2 Test Type—4-point or combined tension (or com-
center of each pin and L = distance between the load applica-
pression) and bending.
tion axis, that is, the pin center, and the neutral axis of the A1.8.1.3 Fixation Geometry—Load point separation dis-
staple bridge, M = FL (see Fig. A1.3).
tances (4-point bending), load offset distance (combined ten-
bending
sion and bending), staple bridge-extension distance, and so
NOTE A1.5—The application of this test method produces bending,
forth.
tensile(orcompressive),andshearstressesinthestaple.Thedirectionand
A1.8.1.4 Minimum and maximum cycle loads, test fre-
magnitudes of these stresses should be analyzed using superposition
theory or other suitable methods. quency(forexample,cycles/s),andforcingfunctiontype(sine,
ramp, saw tooth, and so forth).
A1.6.3.4 Continue the test until failure of the staple or the
A1.8.1.5 Bending moment, M (N-m).
fixation or a predetermined number of load cycles has been
A1.8.1.6 Load ratio, R, where R = minimum load/maximum
applied.
load.
A1.6.4 Stress Verification—It is recommended that strain
A1.8.1.7 Test Environment—Ambient air or physiological
gages(orextensometry)beusedtomeasurethebendingstrains
solution.
induced in the specimen. This is accomplished most easily on
A1.8.1.8 Number of cycles at failure or test termination
thestaplebridge,butitmaybepossibletoperformonaportion
(runout).
of the staple leg or at the leg-bridge junction under certain
A1.8.1.9 Location of fatigue fracture (if applicable).
circumstances and with certain staple designs. The recom-
A1.8.1.10 Reason for test termination, that is, staple failure,
mended technique is to strain gage the actual fatigue test
fixation failure, runout to specified cycle limit, and so forth.
specimens, if possible, provided that the installation of strain
gage will not influence the test results.
A1.9 Precision
A1.7 Test Termination
A1.9.1 Intralaboratory and interlaboratory reproducibility
have not been determined systematically.
A1.7.1 Continue the tests until the specimen fails or a
predetermined number of cycles has been applied to the
A1.10 Rationale (Nonmandatory Information)
specimen. Failure should be defined as complete separation, a
A1.10.1 Thistestmethodisintendedtoaidincharacterizing
crack visible at a specified ma
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