ASTM F3437-23

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: F3437 − 23
Standard Test Methods for
Metallic Bone Plates Used in Small Bone Fracture Fixation
This standard is issued under the fixed designation F3437; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.7 Multiple tests are cited in this standard. However, it
must be noted that the user is not obligated to test using all of
1.1 This standard is intended to provide guidance for the
the described methods. Instead, the user should only select test
static testing of small bone metallic plates used for fracture
methods that are appropriate for a particular device design.
fixation. Small bone plates referred to in this standard would be
1.8 This standard does not purport to address all of the
used in minimally load-bearing anatomical areas of the far
safety concerns, if any, associated with its use. It is the
extremities, such as the fingers and toes, and in the cranium and
responsibility of the user of this standard to establish appro-
upper face. Lower face/mandible, wrist, and ankle fixation
priate safety, health, and environmental practices and deter-
plates would generally be larger and carry a substantial amount
mine the applicability of regulatory limitations prior to use.
of load and should not be evaluated under this standard.
1.9 This international standard was developed in accor-
1.2 ASTM Specification F382 and ISO 9585 are currently
dance with internationally recognized principles on standard-
available for the testing of metallic bone plates as well, so the
ization established in the Decision on Principles for the
user can choose to use any of the tests in these standards for
Development of International Standards, Guides and Recom-
small bone plates. However, due to plate size, Specification
mendations issued by the World Trade Organization Technical
F382 and ISO 9585 test setup and execution difficulty can be
Barriers to Trade (TBT) Committee.
increased for small bone plates. Thus, this standard offers
alternative test methods that are more appropriate for metallic
2. Referenced Documents
bone plates used in small bone fracture fixation.
2.1 ASTM Standards:
1.3 This standard is not intended to address the mechanical
E4 Practices for Force Calibration and Verification of Test-
performance of the plating construct or accessory components
ing Machines
(for example, screws and wires).
E2309/E2309M Practices for Verification of Displacement
Measuring Systems and Devices Used in Material Testing
1.4 This standard is intended to provide a basis for the
Machines
mechanical comparison of small bone plates. Due to the
E2624 Practice for Torque Calibration of Testing Machines
complex and varying biomechanics found in the areas of the
F382 Specification and Test Method for Metallic Bone Plates
body where these plates are used, this standard should only be
F983 Practice for Permanent Marking of Orthopaedic Im-
used to compare the in vitro mechanical performance of small
plant Components
bone plates and not used to infer in vivo performance charac-
F2503 Practice for Marking Medical Devices and Other
teristics.
Items for Safety in the Magnetic Resonance Environment
1.5 This standard describes static tests by specifying load
2.2 ISO Standards:
types and specific methods of applying these loads. Tests for
ISO 9585 Implants for surgery—Determination of bending
evaluating and characterizing these loads include the follow-
strength and stiffness of bone plates
ing: static torsion, static cantilever beam bending, static lateral
ISO 14602 Non-active surgical implants—Implants for
bending, and static three-point bending.
osteosynthesis—Particular requirements
1.6 The values stated in SI units are to be regarded as
3. Terminology
standard. No other units of measurement are included in this
3.1 Definitions – Geometric:
standard.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
These test methods are under the jurisdiction of ASTM Committee F04 on contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Medical and Surgical Materials and Devices and are the direct responsibility of Standards volume information, refer to the standard’s Document Summary page on
Subcommittee F04.21 on Osteosynthesis. the ASTM website.
Current edition approved April 1, 2023. Published April 2023. DOI: 10.1520/ Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
F3437-23. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F3437 − 23
3.1.1 bone plate—a metallic device with two or more holes 3.2.2 bending or torsional stiffness, K (N/mm or Nmm/
or slot(s), or both, and a cross section that consists of at least degree)—the maximum slope of the linear elastic portion of the
two dimensions (width and thickness). The device is intended
load (or torque) displacement curve for a bone plate (see line
to provide alignment and fixation of two or more bone sections,
at Point B in Fig. 1).
primarily by spanning the fracture or defect. The device is
3.2.3 bending ultimate load or ultimate torque (N or
typically fixed to the bone using bone screws.
Nmm)—the maximum compressive load or the maximum
3.1.2 bone plate length, L (mm)—the linear dimension of the
torque applied to the implant (see Point E in Fig. 1). The
bone plate measured along the longitudinal axis, as illustrated
ultimate load or torque should be a function of the device and
in Fig. 2.
not of the load cell or testing machine.
3.1.3 bone plate thickness, b (mm)—the linear dimension of
3.2.4 bending yield load or yield torque (N or Nmm)—the
the bone plate measured parallel to the screw hole axis, as
bending load or torque necessary to produce permanent defor-
shown in Fig. 2. For a bone plate with a crescent section, the
mation equal to 0.002 times the active length or moment arm
thickness is measured at the thickest point along the section
(for load) or 2° (for torque) exposed to testing (see Point D in
(see Fig. 3).
Fig. 1).
3.1.4 bone plate width, w (mm)—the linear dimension of the
bone plate measured perpendicular to both the length and
3.2.5 bending yield moment (Nmm)—bending moment, de-
thickness axes, as shown in Fig. 2.
fined as the moment arm times load, at the yield load.
3.1.5 contouring—the manipulation and bending of a bone
3.2.6 coordinate system/axes—three orthogonal axes are
plate, either preoperatively or intraoperatively, to match the
defined by the following. The center of the coordinate system
anatomic geometry of the intended fixation location.
is located at the geometric center of the bone plate. The length
3.1.6 crescent section—a bone plate cross section shape
and width of the bone plate would lie in the X-Y plane (see Fig.
(perpendicular to the long axis of the bone plate) where the
2). The positive Z-axis is directed superiorly. The compressive
thickness is not constant along the section. Typically, the
axial force is defined as the component in the negative
section is thickest along the bone plate’s center line and tapers
Z-direction. Torsional load is defined as the component of
to a smaller thickness at the bone plate’s edges (see Fig. 3).
torque about the X-axis. Lateral load is defined in the negative
3.1.7 uniform width—referring to a bone plate where the
Y-direction.
width is constant along the bone plate’s length.
3.2.7 displacement at offset yield (mm or degrees)—the
3.2 Definitions – Mechanical/Structural:
displacement of a plate at the yield load (or torque) (see Point
3.2.1 active length—the straight-line distance representing
A in Fig. 1).
the portion of the plate being tested; for example, for torsion
3.2.8 offset displacement (mm or degrees)—offset equal to
testing, the distance between the test fixtures (see Fig. 4); for
2° (for torsion) or 0.002 times the active length or moment arm
three-point bending, the active length would be “H” in Fig. 7
(see 8.7). (see Point F in Fig. 1).
FIG. 1 Typical Load (or Torque) Displacement Curve
F3437 − 23
FIG. 2 Basic Two-Hole Small Bone Plate and Dimensions
FIG. 3 Bone Plate Cross Sections
3.2.9 ultimate displacement or ultimate angular displace- due to irregular screw hole patterns or the shape of the plate, it
ment (mm or degrees)—the displacement or angular displace- is understandable that some tests would need to be modified, or
ment associated with the ultimate load or torque (see Point C possibly removed from test consideration, to accommodate the
in Fig. 1). shape of the plate or the screw hole. Any test modifications or
omissions shall be described in the final report with a rationale
4. Significance and Use
related to the plate’s anatomical use, indications, and functional
requirements.
4.1 Due to the variety of small bone fractures, plates used
for the fixation of these fractures come in a variety of shapes
5. Marking, Packaging, Labeling, and Handling
and configurations. Table 1 categorizes the plate types for each
5.1 Dimensions of bone plates should be designated by the
anatomical area. Flat plates are the simplest; see Fig. 2 for an
standard definitions given in
example of a basic flat plate. Many other plates have features 3.1.
to accommodate specific anatomies, such as condylar, complex
5.2 Bone plates shall be marked using a method specified in
(such as cuneiform), pre-contoured (such as metatarsophalan-
accordance with either Practice F983 or ISO 14602.
geal joint (MPJ)), step, orbital, orthognathic step, and wedge
5.3 If plates are large enough, markings on the plates shall
plates. Other plates, such as mesh-based and burr hole plates,
identify the manufacturer or distributor and shall be located
are generally flat but are designed to be used in specific
away from the most highly stressed areas, if possible.
anatomical regions, so their designs are not the same as
conventional straight plates. If test data is used from one type 5.4 Packaging shall be adequate to maintain original plate
of plate for justification of the mechanical properties of another specifications.
type of plate, this justification shall be described in the final
5.5 Package labeling for bone plates shall include, when
report.
possible, the following information:
4.2 Most of the testing described herein is focused on a 5.5.1 Manufacturer and product name;
“functional unit,” which can be described as a single-line 5.5.2 Catalog number;
fracture being spanned by a plate with one screw hole on each 5.5.3 Lot or serial number;
side of the fracture. This configuration allows for the simplest 5.5.4 Unique identifier numbers, such as Global Trade Item
determination of worst-case size if the strut geometry is the Number (GTIN), if applicable to market;
determining factor for the worst case. If a worst-case size 5.5.5 Material and, where applicable, its associated ASTM
cannot be isolated to a functional unit/strut geometry, perhaps or ISO specification designation number;
F3437 − 23
NOTE 1—To prevent looseness of the plate at the pins, washers shall be used to rigidly secure the plate.
FIG. 4 Suggested Torsion Apparatus—Wire Frame Side View and Top View
TABLE 1 Plate Types for Each Anatomical Area
6. Materials
Anatomical Location Geometric Type
6.1 Bone plates shall be fabricated from a metallic material
Maxillofacial (non-mandible) Flat
intended for surgical implant applications. In addition, the
Orbital Floor
Orthognathic Step
materials shall be biocompatible for the intended application.
Materials should be chosen based on the design requirements
Hand Flat
of the particular device. ASTM Subcommittee F04.12 main-
Condylar
tains a number of standard specifications for metallic materials
Fo
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