1、Designation: F2502 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 revision, t
2、he 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 mechani-cal characterization of plates and screws for orthope
3、dic internalfixation. Covered devices are fabricated from one or morehydrolytically degradable polymer (from this point on referredto as “absorbable”) resins or resin composites.1.2 This specification establishes a common terminology todescribe the size and other physical characteristics of absorb-a
4、ble implants and performance definitions related to theperformance of absorbable devices.1.3 This specification establishes standard test methods toconsistently measure performance-related mechanical charac-teristics of absorbable devices when tested under definedconditions of pretreatment, temperat
5、ure, humidity, and testingmachine speed.1.4 This specification may not be appropriate for all absorb-able devices, especially those that possess limited hydrolyticsusceptibility and degrade in vivo primarily through enzymaticaction. The user is cautioned to consider the appropriateness ofthe standar
6、d in view of the particular absorbable device and itspotential application.1.5 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its
7、use. It is theresponsibility of the user of this standard to establish appro-priate safety, health and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.7 This international standard was developed in accor-dance with internationally recognized principl
8、es on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D790 Test Methods for Flexural Prop
9、erties of Unreinforcedand Reinforced Plastics and Electrical Insulating Materi-alsE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE122 Practice for Calculating Sample Size to Estimate, WithSpecified Precision, the Average for a Character
10、istic of aLot or ProcessE1823 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 MedicalBone ScrewsF565 Practice for Care and Handling of Orthop
11、edic Implantsand InstrumentsF1088 Specification for Beta-Tricalcium Phosphate for Sur-gical ImplantationF1185 Specification for Composition of Hydroxylapatite forSurgical ImplantsF1635 Test Method for in vitro Degradation Testing ofHydrolytically Degradable Polymer Resins and FabricatedForms for Sur
12、gical ImplantsF1839 Specification for Rigid Polyurethane Foam for Use asa Standard Material for Testing Orthopaedic Devices andInstrumentsF1925 Specification for Semi-Crystalline Poly(lactide) Poly-mer and Copolymer Resins for Surgical ImplantsF2313 Specification for Poly(glycolide) and Poly(glycoli
13、de-co-lactide) Resins for Surgical Implants with Mole Frac-tions Greater Than or Equal to 70 % GlycolideF2503 Practice for Marking Medical Devices and OtherItems for Safety in the Magnetic Resonance EnvironmentF2579 Specification for Amorphous Poly(lactide) andPoly(lactide-co-glycolide) Resins for S
14、urgical ImplantsF2902 Guide for Assessment of Absorbable Polymeric Im-plants1This specification and test methods is under the jurisdiction of ASTMCommittee F04 on Medical and Surgical Materials and Devices and is the directresponsibility of Subcommittee F04.21 on Osteosynthesis.Current edition appro
15、ved Sept. 1, 2017. Published October 2017. Originallyapproved in 2005. Last previous edition approved in 2011 as F2502 11. DOI:10.1520/F2502-17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards v
16、olume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on st
17、andardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1F3160 Guide for Metallurgical Characterization of Absorb-able Metallic Materials for M
18、edical Implants2.2 ISO Standards:3ISO 13781 Poly (L-Lactide) Resins and Fabricated Formsfor Surgical ImplantsIn Vitro Degradation TestingISO 14630 Non-Active Surgical ImplantsGeneral Re-quirementsISO 15814 Copolymers and Blends Based onPolylactideIn Vitro Degradation Testing3. Terminology3.1 Definit
19、ions:3.1.1 Unless otherwise defined in this specification, theterminology related to mechanical testing that is used in thesetest methods will be in accordance with the definitions ofTerminologies E6 and E1823, and Specifications F382 andF543.3.2 General Definitions:3.2.1 absorbable, adjin the body,
20、 referring to an initiallydistinct foreign material or substance that either directly orthrough intended degradation can pass through or be assimi-lated 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 composi
21、tean absorbable polymer resinor construct incorporating a particulate and/or fibrous bioactiveand/or absorbable filler material.3.2.3 bone anchora device or a component of a devicethat provides the attachment to the bone.3.2.4 bone platea device, when affixed with screws orcerclage wire, intended to
22、 provide alignment of two or morebone sections, primarily by spanning the fracture or defect. Abone plate has two or more holes. Its width and thicknessusually are not the same in magnitude.3.2.5 deteriorationthe reduction or worsening of me-chanical or other functional performance properties of ade
23、vice.3.2.6 hydrolytically degradable polymerany polymericmaterial in which the primary mechanism of chemical degra-dation in the body is by hydrolysis (water reacting with thepolymer resulting in cleavage of the chain).3.2.7 suture anchora device that provides a means toattach soft tissue to bone wi
24、th a suture.3.3 Definitions of Terms Specific to This Standard:3.3.1 insertion depth (mm)the linear advancement of adevice into the test block measured relative to its seatedposition at the test blocks surface prior to testing.4. Significance and Use4.1 Absorbable devices are intended to degrade and
25、 absorbover time once they are implanted into the body. This makes aremoval operation unnecessary, which is especially advanta-geous for pediatric patients.4.2 While the polymer degrades due to hydrolytic reactionwith the environment, the mechanical performance of thedevice also deteriorates. The ke
26、y to developing mechanicallyeffective fracture fixation systems based on absorbable devicesis to provide an adequate level of fixation strength and stiffnessfor a time frame that exceeds that expected for fracture healing.Once the fracture is healed, the device can be completelyabsorbed by the body.
27、 The biological performance of thedevice, particularly for application at a bony site, may beenhanced by incorporation of bioactive fillers in the polymer.4.3 Absorbable devices will be tested using test methodsthat are similar to those used to evaluate conventional metallicdevices. The pre-test con
28、ditioning requirements, handlingrequirements, and time-dependent mechanical property evalu-ations for absorbable devices shall be considered.4.4 This specification and accompanying test methods areintended to complement the more general considerations forthe assessment of absorbable polymeric implan
29、ts that aredescribed within Guide F2902.5. Materials and Manufacture5.1 Absorbable devices may be fabricated from one of thefollowing materials:5.1.1 L-lactide, D-lactide, D, L-lactide, glycolide, or otherknown hydrolytically degradable polymer resins or copoly-mers. (for additional information, see
30、 complementary testmethods found in ISO 13781, ISO 15814, and F1635, and inrelated Specifications F1925, F2313, and F2579.)5.1.2 Other absorbable polymeric, ceramic, or metallicbased constructs that degrade through non-hydrolytic means,such as those described in Specifications F1088 and F1185, andGu
31、ide F3160 may be considered, but precautions should beundertaken to assure a materials-appropriate degradation envi-ronment is maintained.5.2 The manufacturer shall ensure that materials used tomanufacture absorbable implants are suitable for implantinginto the body. Methods to evaluate a materials
32、suitability aredescribed in ISO 14630.5.3 All absorbable devices made of materials that have anASTM committee F04 or D20 standard designation or an ISOdesignation shall meet those requirements given in the ASTMstandards.6. General Requirements and PerformanceConsiderations6.1 Absorbable Bone ScrewsT
33、he following propertiesmay be important when determining the suitability of a screw3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org. FIG. 1 Screw ParametersF2502 172for a particular application. However, the test methods r
34、efer-enced as follows may not be appropriate for all types ofimplant applications. The user is cautioned to consider theappropriateness of the test methods in view of the devicesbeing tested and their potential application.6.1.1 Offset Yield Strength is the stress at which the stress-strain curve de
35、parts from linearity by a specified percent ofdeformation (offset).6.1.2 Torsional Strength is an important parameter to pre-vent screw breakage during insertion. The torsional strengthshall be determined using the test methods described in AnnexA1.6.1.3 Driving Torque is an important parameter to a
36、voidfailure of the screw during insertion and to ensure that thescrew may be easily inserted by the surgeon. The insertiontorque should be much less than the torsional yield strength ofthe screw as well as that of the appropriate screwdriver bit. Theinsertion torque may be determined using the test
37、methodsdescribed in Annex A2.6.1.4 Axial Pullout Strength is an important parameter if thescrew is subjected to axial tensile forces, or if the screw is fixedinto poor quality or osteoporotic bone. The pullout strengthmay be determined using the test methods described in AnnexA3.6.2 Absorbable Bone
38、Plates:6.2.1 Geometric ConsiderationsBone plates that are in-tended to be used with bone screws shall have design features(screw holes or slots) that conform to or appropriately fit thecorresponding bone screw.6.2.2 Bending PropertiesThe bending properties are criti-cal characteristics of bone plate
39、s for orthopedic applicationssince the bone plate provides the primary means of stabilizingthe bone fragments. In addition, the bending stiffness of thebone plate may affect the rate and quality of healing.6.2.2.1 The relevant bending properties (bending stiffness,bending structural stiffness, and b
40、ending strength) shall bedetermined using the standard test method of Annex A4.7. General Sampling, Conditioning, and TestingConsiderations7.1 Apparatus, Equipment, and Materials:7.1.1 Sample ContainerA self-enclosed glass or plasticcontainer capable of holding the test sample and the condition-ing
41、solution shall be used. The container shall be sealable toprevent solution loss due to evaporation. Multiple samples maybe stored in the same container provided that suitable sampleseparation is maintained to allow fluid access to each samplesurface and to preclude sample-to-sample contact.7.1.2 Con
42、ditioning/Soaking SolutionAphosphate bufferedsaline (PBS) or other adequately pH-controlled aqueous solu-tion shall be used. The pH of the solution shall be maintainedat 7.4 6 0.2 (see Test Method F1635, Section X1.3). The pHshould be monitored frequently and, if necessary, the solutionshall be chan
43、ged periodically in order to maintain the pHwithin the acceptable limits. These materials may be hazardousand all persons using them should review the material safetydata sheet (MSDS) before handling and use all recommendedsafety precautions.7.1.2.1 Other physiologic relevant solutions may be substi
44、-tuted provided the solution is properly buffered. An anti-microbial additive should be used to inhibit the growth ofmicroorganisms in the solution during the test period. Theinvestigator shall demonstrate that the chosen antimicrobialdoes not affect the absorption rate (see X1.3).7.1.3 Constant Tem
45、perature Bath or OvenAn aqueousbath or heated air oven capable of maintaining the samples andcontainers at a physiologic temperature (37 6 2C) for thespecified testing periods shall be used. It shall be well stirredduring the test and shall be provided with a means of raisingthe temperature at a uni
46、form rate.7.1.4 pH MeterA pH metering device sensitive in thephysiological range (pH 6 to pH 8) with a precision of 0.02 orbetter shall be used.7.1.5 BalanceA calibrated weighing device capable ofmeasuring the weight of a sample to a precision of 0.1 % of itsinitial weight shall be used.7.1.6 Drivin
47、g InstrumentsSpecification F116 provides re-lated dimensional information for several types of medicalscrewdrivers7.2 Sample Acquisition and Evaluation Frequency:7.2.1 SamplingIf appropriate, representative randomsamples shall be taken from each lot or processing quantity inaccordance with Practice
48、E122. The test specimen shall be acompletely fabricated and finished absorbable bone screwsterilized as intended by the manufacturer.7.2.2 Conditioning IntervalsFor a complete history of thebehavior of a sample during absorption, there should be at leastseven measuring points spanning the duration o
49、f mechanicallongevity. For example, 0 h, 1 day, 1 week, 4 weeks, 8 weeks,12 weeks, 16 weeks, and 24 weeks may be appropriate forL-PLA based devices. An initial (0 h) sample is to be testedwithout conditioning, while data acquired at 1 day post-immersion provides representation of an initial equilibration ofthe sample within the conditioning solution. The testingintervals shall be documented in the test report.7.3 Sample Conditioning:7.3.1 Test specimens shall be conditioned by immersion ina pH-controlled aqueous solution at physiologic temperatur
