1、Designation: F2502 11F2502 17Standard Specification and Test Methods forAbsorbable Plates and Screws for Internal FixationImplants1This standard is issued under the fixed designation F2502; the number immediately following the designation indicates the year oforiginal adoption or, in the case of rev
2、ision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification and test methods cover the mechanical characterization of plates and screws for
3、orthopedic internalfixation. Covered devices are fabricated from one or more hydrolytically degradable polymer (from this point on referred to as“absorbable”) resins or resin composites.1.2 This specification establishes a common terminology to describe the size and other physical characteristics of
4、 absorbableimplants and performance definitions related to the performance of absorbable devices.1.3 This specification establishes standard test methods to consistently measure performance-related mechanical characteristicsof absorbable devices when tested under defined conditions of pretreatment,
5、temperature, humidity, and testing machine speed.1.4 This specification may not be appropriate for all absorbable devices, especially those that possess limited hydrolyticsusceptibility and degrade in vivo primarily through enzymatic action. The user is cautioned to consider the appropriateness of t
6、hestandard in view of the particular absorbable device and its potential application.1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.6 This standard does not purport to address all of the safety concerns, if any, associa
7、ted with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use.1.7 This international standard was developed in accordance with international
8、ly recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D790 Test Metho
9、ds for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating MaterialsE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE122 Practice for Calculating Sample Size to Estimate, With Specified Precision, the Av
10、erage for a Characteristic of a Lot orProcessE1823 Terminology Relating to Fatigue and Fracture TestingF116 Specification for Medical Screwdriver BitsF382 Specification and Test Method for Metallic Bone PlatesF543 Specification and Test Methods for Metallic Medical Bone ScrewsF565 Practice for Care
11、and Handling of Orthopedic Implants and InstrumentsF1088 Specification for Beta-Tricalcium Phosphate for Surgical ImplantationF1185 Specification for Composition of Hydroxylapatite for Surgical ImplantsF1635 Test Method for in vitro Degradation Testing of Hydrolytically Degradable Polymer Resins and
12、 Fabricated Forms forSurgical Implants1 This specification and test methods is under the jurisdiction of ASTM Committee F04 on Medical and Surgical Materials and Devices and is the direct responsibilityof Subcommittee F04.21 on Osteosynthesis.Current edition approved June 1, 2011Sept. 1, 2017. Publi
13、shed July 2011October 2017. Originally approved in 2005. Last previous edition approved in 20092011 asF2502 05 (2009)F2502 11.1. DOI: 10.1520/F2502-11.10.1520/F2502-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual
14、Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be tec
15、hnically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO
16、 Box C700, West Conshohocken, PA 19428-2959. United States1F1839 Specification for Rigid Polyurethane Foam for Use as a Standard Material for Testing Orthopaedic Devices andInstrumentsF1925 Specification for Semi-Crystalline Poly(lactide) Polymer and Copolymer Resins for Surgical ImplantsF2313 Speci
17、fication for Poly(glycolide) and Poly(glycolide-co-lactide) Resins for Surgical Implants with Mole Fractions GreaterThan or Equal to 70 % GlycolideF2503 Practice for Marking Medical Devices and Other Items for Safety in the Magnetic Resonance EnvironmentF2579 Specification for Amorphous Poly(lactide
18、) and Poly(lactide-co-glycolide) Resins for Surgical ImplantsF2902 Guide for Assessment of Absorbable Polymeric ImplantsF3160 Guide for Metallurgical Characterization of Absorbable Metallic Materials for Medical Implants2.2 ISO Standards:3ISO 13781 Poly (L-Lactide) Resins and Fabricated Forms for Su
19、rgical ImplantsIn Vitro Degradation TestingISO 14630 Non-Active Surgical ImplantsGeneral RequirementsISO 15814 Copolymers and Blends Based on PolylactideIn Vitro Degradation Testing3. Terminology3.1 Definitions:3.1.1 Unless otherwise defined in this specification, the terminology related to mechanic
20、al testing that is used in these testmethods will be in accordance with the definitions of Terminologies E6 and E1823, and Specifications F382 and F543.3.2 General Definitions:3.2.1 absorbable, adjin the body, referring to an initially distinct foreign material or substance that either directly or t
21、hroughintended degradation can pass through or be assimilated by cells and/or tissue.NOTE 1See Appendix X1.5 for a discussion regarding the usage of “absorbable” and other related terms.3.2.2 absorbable compositean absorbable polymer resin or construct incorporating a particulate and/or fibrous bioa
22、ctiveand/or absorbable filler material.3.2.3 bone anchora device or a component of a device that provides the attachment to the bone.3.2.4 bone platea device, when affixed with screws or cerclage wire, intended to provide alignment of two or more bonesections, primarily by spanning the fracture or d
23、efect. A bone plate has two or more holes. Its width and thickness usually are notthe same in magnitude.3.2.5 deteriorationthe reduction or worsening of mechanical or other functional performance properties of a device.3.2.6 hydrolytically degradable polymerany polymeric material in which the primar
24、y mechanism of chemical degradation inthe body is by hydrolysis (water reacting with the polymer resulting in cleavage of the chain).3.2.7 suture anchora device that provides a means to attach soft tissue to bone with a suture.3.3 Definitions of Terms Specific to This Standard:3.3.1 insertion depth
25、(mm)the linear advancement of a device into the test block measured relative to its seated position atthe test blocks surface prior to testing.4. Significance and Use4.1 Absorbable devices are intended to degrade and absorb over time once they are implanted into the body. This makes aremoval operati
26、on unnecessary, which is especially advantageous for pediatric patients.4.2 While the polymer degrades due to hydrolytic reaction with the environment, the mechanical performance of the device alsodeteriorates. The key to developing mechanically effective fracture fixation systems based on absorbabl
27、e devices is to provide anadequate level of fixation strength and stiffness for a time frame that exceeds that expected for fracture healing. Once the fractureis healed, the device can be completely absorbed by the body. The biological performance of the device, particularly for applicationat a bony
28、 site, may be enhanced by incorporation of bioactive fillers in the polymer.4.3 Absorbable devices will be tested using test methods that are similar to those used to evaluate conventional metallic devices.The pre-test conditioning requirements, handling requirements, and time-dependent mechanical p
29、roperty evaluations forabsorbable devices shall be considered.4.4 This specification and accompanying test methods are intended to complement the more general considerations for theassessment of absorbable polymeric implants that are described within Guide F2902.5. Materials and Manufacture5.1 Absor
30、bable devices may be fabricated from one of the following materials:3 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi.org.F2502 1725.1.1 L-lactide, D-lactide, D, L-lactide, glycolide, or other known hydrolytically degradable
31、polymer resins or copolymers. (SeeISO 13781, ISO 15814,Test Method (for additional information, see complementary test methods found in ISO 13781, ISO 15814,and F1635, and in related Specifications F1925, F1088F2313, and F1185F2579.)5.1.2 Other absorbable polymeric, ceramic, or metallic based constr
32、ucts that degrade through non-hydrolytic means, such asthose described in Specifications F1088 and F1185, and Guide F3160 may be considered, but precautions should be undertakento assure a materials-appropriate degradation environment is maintained.5.2 The manufacturer shall ensure that materials us
33、ed to manufacture absorbable implants are suitable for implanting into thebody. Methods to evaluate a materials suitability are described in ISO 14630.5.3 All absorbable devices made of materials that have an ASTM committee F04 or D20 standard designation or an ISOdesignation shall meet those requir
34、ements given in the ASTM standards.6. General Requirements and Performance Considerations6.1 Absorbable Bone ScrewsThe following properties may be important when determining the suitability of a screw for aparticular application. However, the test methods referenced as follows may not be appropriate
35、 for all types of implant applications.The user is cautioned to consider the appropriateness of the test methods in view of the devices being tested and their potentialapplication.6.1.1 Offset Yield Strength is the stress at which the stress-strain curve departs from linearity by a specified percent
36、 ofdeformation (offset).6.1.2 Torsional Strength is an important parameter to prevent screw breakage during insertion. The torsional strength shall bedetermined using the test methods described in Annex A1.6.1.3 Driving Torque is an important parameter to avoid failure of the screw during insertion
37、and to ensure that the screw maybe easily inserted by the surgeon. The insertion torque should be much less than the torsional yield strength of the screw as wellas that of the appropriate screwdriver bit. The insertion torque may be determined using the test methods described in Annex A2.6.1.4 Axia
38、l Pullout Strength is an important parameter if the screw is subjected to axial tensile forces, or if the screw is fixedinto poor quality or osteoporotic bone. The pullout strength may be determined using the test methods described in Annex A3.6.2 Absorbable Bone Plates:6.2.1 Geometric Consideration
39、sBone plates that are intended to be used with bone screws shall have design features (screwholes or slots) that conform to or appropriately fit the corresponding bone screw.6.2.2 Bending PropertiesThe bending properties are critical characteristics of bone plates for orthopedic applications since t
40、hebone plate provides the primary means of stabilizing the bone fragments. In addition, the bending stiffness of the bone plate mayaffect the rate and quality of healing.6.2.2.1 The relevant bending properties (bending stiffness, bending structural stiffness, and bending strength) shall bedetermined
41、 using the standard test method of Annex A4.7. General Sampling, Conditioning, and Testing Considerations7.1 Apparatus, Equipment, and Materials:7.1.1 Sample ContainerA self-enclosed glass or plastic container capable of holding the test sample and the conditioningsolution shall be used. The contain
42、er shall be sealable to prevent solution loss due to evaporation. Multiple samples may be storedin the same container provided that suitable sample separation is maintained to allow fluid access to each sample surface and topreclude sample-to-sample contact.7.1.2 Conditioning/Soaking SolutionA phosp
43、hate buffered saline (PBS) or other adequately pH-controlled aqueous solutionshall be used. The pH of the solution shall be maintained at 7.4 6 0.2 (see Test Method F1635, Section X1.3). The pH should bemonitored frequently and, if necessary, the solution shall be changed periodically in order to ma
44、intain the pH within the acceptablelimits. These materials may be hazardous and all persons using them should review the material safety data sheet (MSDS) beforehandling and use all recommended safety precautions.FIG. 1 Screw ParametersF2502 1737.1.2.1 Other physiologic relevant solutions may be sub
45、stituted provided the solution is properly buffered. An anti-microbialadditive should be used to inhibit the growth of microorganisms in the solution during the test period. The investigator shalldemonstrate that the chosen antimicrobial does not affect the absorption rate (see X1.3).7.1.3 Constant
46、Temperature Bath or OvenAn aqueous bath or heated air oven capable of maintaining the samples andcontainers at a physiologic temperature (37 6 2C) for the specified testing periods shall be used. It shall be well stirred duringthe test and shall be provided with a means of raising the temperature at
47、 a uniform rate.7.1.4 pH MeterA pH metering device sensitive in the physiological range (pH 6 to pH 8) with a precision of 0.02 or bettershall be used.7.1.5 BalanceA calibrated weighing device capable of measuring the weight of a sample to a precision of 0.1 % of its initialweight shall be used.7.1.
48、6 Driving InstrumentsSpecification F116 provides related dimensional information for several types of medicalscrewdrivers7.2 Sample Acquisition and Evaluation Frequency:7.2.1 SamplingIf appropriate, representative random samples shall be taken from each lot or processing quantity inaccordance with P
49、ractice E122. The test specimen shall be a completely fabricated and finished absorbable bone screw sterilizedas intended by the manufacturer.7.2.2 Conditioning IntervalsFor a complete history of the behavior of a sample during absorption, there should be at leastseven measuring points spanning the duration of mechanical longevity. For example, 0 h, 1 day, 1 week, 4 weeks, 8 weeks, 12weeks, 16 weeks, and 24 weeks may be appropriate for L-PLA based devices. An initial (0 h) sample is to be tested withoutconditioning, while data acquired at 1 day post
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