1.1 This specification is intended to provide a characterization of the design and mechanical function of intramedullary fixation devices (IMFDs), specify labeling and material requirements, provide test methods for characterization of IMFD mechanical properties, and identify needs for further development of test methods and performance criteria. The ultimate goal is to develop a standard which defines performance criteria and methods for measurement of performance-related mechanical characteristics of IMFDs and their fixation to bone. It is not the intention of this specification to define levels of performance or case-specific clinical performance of these devices, as insufficient knowledge to predict the consequences of the use of any of these devices in individual patients for specific activities of daily living is available. It is not the intention of this specification to describe or specify specific designs for IMFDs.

1.2 This specification describes IMFDs for surgical fixation of the skeletal system. It provides basic IMFD geometrical definitions, dimensions, classification, and terminology; labeling and material specifications; performance definitions; test methods and characteristics determined to be important to in-vivo performance of the device.

1.3 This specification includes four standard test methods:

1.3.1 Static Four-Point Bend Test Method-Annex A1 and

1.3.2 Static Torsion Test Method-Annex A2.

1.3.3 Bending Fatigue Test Method-Annex A3.

1.3.4 Test Method for Bending Fatigue of IMFD Locking Screws-Annex A4.

1.4 A rationale is given in Appendix X1.

1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

A1.1.1 This test method describes methods for static four-point bend testing of intrinsic, structural properties of intramedullary fixation devices (IMFDs) for surgical fixation of the skeletal system. This test method includes bend testing in a variety of planes relative to the major anatomic planes. The purpose is to measure bending strength and bending stiffness intrinsic to the design and materials of IMFDs.

A1.1.2 This test method is designed specifically to test IMFD designs that have a well-defined working length (WL) of uniform open or closed cross section throughout the majority of its length (WL ≥ 10× diameter) and is to be applied to the full length of the diaphysis of a femur, tibia, humerus, radius, or ulna. This is not applicable to IMFDs that are used to fix only a short portion of the diaphysis of any of the long bones or the diaphysis of small bones such as the metacarpals, metatarsals, phalanges, and so forth.

A1.1.3 This test method is not intended to test the extrinsic properties of any IMFD, that is, the interaction of the device with bone or other biologic materials.

A1.1.4 This test method is not intended to define case-specific clinical performance of these devices, as insufficient knowledge to predict the consequences of the use of any of these devices in individual patients is available.

A1.1.5 This test method is not intended to serve as a quality assurance document, and thus, statistical sampling techniques for batches from production of IMFDs are not addressed.

A1.1.6 This test method may not be appropriate for all types of implant applications. The user is cautioned to consider the appropriateness of the method in view of the devices being tested, the material of their manufacture, and their potential applications.

A1.1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

A1.1.8 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 and health practices and determine the applicability of regulatory limitations prior to use.

A2.1.1 This test method covers the test procedure for determining the torsional stiffness of intramedullary fixation devices (IMFDs). The central part of the IMFD, with a straight and uniform cross-section and away from screw holes or other interlocking features, is tested in a static test.

A2.1.2 IMFDs are indicated for surgical fixation of the skeletal system and are typically used in the femur, tibia, humerus, radius, or ulna. Devices that meet the IMFD specifications of Section 4, and other similar devices, are covered by this test method.

A2.1.3 This test method does not intend to test or provide information that will necessarily relate to the properties of fixation that an IMFD may obtain in a bone or any other connection with other devices.

A2.1.4 This test method is not intended to define case-specific clinical performance of these devices, as insufficient knowledge to predict the consequences of the use of any of these devices in individual patients is available.

A2.1.5 This test method is not intended to serve as a quality assurance document. Thus, statistical sampling techniques for batches from the production of IMFDs are not addressed.

A2.1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

A2.1.7 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.

A3.1.1 This test method covers the test procedure for performing cyclic bending fatigue testing of intramedullary fixation devices (IMFDs). The central part of the IMFD, with a straight and uniform cross section and away from screw holes or other interlocking features, is tested in cyclic four-point bending. This method may be used to determine a fatigue life at a specified maximum bending moment or to estimate a fatigue strength for a specified number of cycles.

A3.1.2 IMFDs are indicated for surgical fixation of the skeletal system and are typically used in the femur, tibia, humerus, radius, or ulna. Devices that meet the IMFD specifications of Section 4, and other similar devices, are covered by this test method.

A3.1.3 This test method is not intended to test or provide information that will necessarily relate to the properties of fixation which an IMFD may obtain in a bone, or any other connection with other devices.

A3.1.4 This test method is not intended to define case-specific clinical performance of these devices, as insufficient knowledge to predict the consequences of the use of any of these devices in individual patients is available.

A3.1.5 This test method is not intended to serve as a quality assurance document, and thus, statistical sampling techniques for batches from the production of IMFDs are not addressed.

A3.1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

A3.1.7 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.

A4.1.1 This test method covers the test procedure for performing cyclic bending fatigue testing of locking screws used for the fixation of intramedullary fixation devices (IMFDs). The central part of the screw is tested in cyclic three-point or four-point bending. This method may be used to determine a fatigue life at a specified maximum bending moment or to estimate a fatigue strength for a specified number of cycles.

A4.1.2 This test method is specifically applicable to screws described by Specification F 543, which are used to provide fixation of IMFDs in bone by transversely crossing through the IMFD from one cortex to the other. This test method may or may not be applicable to other types of orthopaedic bone screws.

A4.1.3 This test method does not address the connection between the IMFD and the screw.

A4.1.4 This test method is not intended to define case-specific clinical performance of these devices, as insufficient knowledge to predict the consequences of the use of any of these devices in individual patients is available.

A4.1.5 This test method is not intended to serve as a quality assurance document, and thus, statistical sampling techniques for batches from the production of screws are not addressed.

A4.1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

A4.1.7 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.