Significance and Use
4.1 Due to the variety of small bone fractures, plates used for the fixation of these fractures come in a variety of shapes and configurations. Table 1 categorizes the plate types for each anatomical area. Flat plates are the simplest; see Fig. 2 for an example of a basic flat plate. Many other plates have features to accommodate specific anatomies, such as condylar, complex (such as cuneiform), pre-contoured (such as metatarsophalangeal joint (MPJ)), step, orbital, orthognathic step, and wedge plates. Other plates, such as mesh-based and burr hole plates, are generally flat but are designed to be used in specific anatomical regions, so their designs are not the same as conventional straight plates. If test data is used from one type of plate for justification of the mechanical properties of another type of plate, this justification shall be described in the final report.
4.2 Most of the testing described herein is focused on a “functional unit,” which can be described as a single-line fracture being spanned by a plate with one screw hole on each side of the fracture. This configuration allows for the simplest determination of worst-case size if the strut geometry is the determining factor for the worst case. If a worst-case size cannot be isolated to a functional unit/strut geometry, perhaps due to irregular screw hole patterns or the shape of the plate, it is understandable that some tests would need to be modified, or possibly removed from test consideration, to accommodate the shape of the plate or the screw hole. Any test modifications or omissions shall be described in the final report with a rationale related to the plate’s anatomical use, indications, and functional requirements.
Scope
1.1 This standard is intended to provide guidance for the static testing of small bone metallic plates used for fracture fixation. Small bone plates referred to in this standard would be used in minimally load-bearing anatomical areas of the far extremities, such as the fingers and toes, and in the cranium and upper face. Lower face/mandible, wrist, and ankle fixation plates would generally be larger and carry a substantial amount of load and should not be evaluated under this standard.
1.2 ASTM Specification F382 and ISO 9585 are currently available for the testing of metallic bone plates as well, so the user can choose to use any of the tests in these standards for small bone plates. However, due to plate size, Specification F382 and ISO 9585 test setup and execution difficulty can be increased for small bone plates. Thus, this standard offers alternative test methods that are more appropriate for metallic bone plates used in small bone fracture fixation.
1.3 This standard is not intended to address the mechanical performance of the plating construct or accessory components (for example, screws and wires).
1.4 This standard is intended to provide a basis for the mechanical comparison of small bone plates. Due to the complex and varying biomechanics found in the areas of the body where these plates are used, this standard should only be used to compare the in vitro mechanical performance of small bone plates and not used to infer in vivo performance characteristics.
1.5 This standard describes static tests by specifying load types and specific methods of applying these loads. Tests for evaluating and characterizing these loads include the following: static torsion, static cantilever beam bending, static lateral bending, and static three-point bending.
1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
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 the described methods. Instead, the user should only select test methods that are appropriate for a particular device design.
1.8 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.9 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.
