1、Designation: F 754 00Standard Specification forImplantable Polytetrafluoroethylene (PTFE) PolymerFabricated in Sheet, Tube, and Rod Shapes1This standard is issued under the fixed designation F 754; the number immediately following the designation indicates the year oforiginal adoption or, in the cas
2、e of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification describes the performance of poly-tetrafluoroethylene (PTFE) fabricated
3、 in sheet, tube, and rodshapes which may be used for surgical implants. PTFE is amember of the generic class of perfluorocarbon (containingonly the elements fluorine and carbon) polymers.1.2 Perfluorocarbon high polymers are solids exhibitingextraordinary thermal and chemical stability. They do notr
4、equire stabilizing additives of any kind.1.3 The biological response to PTFE in soft tissue and bonehas been well characterized by a history of clinical use andanimal studies (1-9).21.4 This specification does not apply to specific surgicalimplants. Such implants would be subject to appropriateend-u
5、se performance standards.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations pri
6、or to use.2. Referenced Documents2.1 ASTM Standards:D 1457 Specification for PTFE Molding and ExtrusionMaterials3D 1710 Specification for Polytetrafluoroethylene (PTFE)Basic Shapes, Rod, and HeavyWalled Tubing4D 1898 Practice for Sampling of Plastics4D 3293 Specification for PTFE Resin Molded Sheet5
7、F 748 Practice for Selecting Generic Biological Test Meth-ods for Materials and Devices6F 749 Practice for Evaluating Material Extracts by Intracu-taneous Injection in the Rabbit6F 750 Practice for Evaluating Material Extracts by SystemicInjection in the Mouse6F 813 Practice for Direct Contact Cell
8、Culture Evaluation ofMaterials for Medical Devices6F 895 Test Method for Agar Diffusion Cell Culture Screen-ing for Cytotoxity6F 981 Practice for Assessment of Compatibility of Bioma-terials (Non-porous) for Surgical Implants with Respect toEffect of Materials on Muscle and Bone63. Significance and
9、Use3.1 Fabricated PTFE meeting the requirements of this speci-fication will exhibit consistent and reproducible chemical,physical, and biological properties.3.1.1 This specification ensures the absence of adulterants,additives, or processing aids.3.1.2 This specification ensures the absence of extra
10、ctableorganic contaminants from fabricated configurations.3.1.3 Fabricated configurations satisfying this specificationshould be compatible with tissue.3.1.4 This specification addresses the characteristics ofvirgin raw molding powders obtained from resin manufacturersand used for producing implant
11、configurations and of configu-rations packaged in either nonsterile or sterile states.3.2 PTFE configurations were first used for implantation inthe early 1950s and have served as compatible implants inlarge numbers of patients since that time with some implantdurations beyond 20 years (1). Reports
12、of reaction to particu-late debris of PTFE in load bearing applications outside of thepressure-velocity (PV) limits for the polymer (10, 11) have notbeen correlated with other biocompatibility assays for thispolymer and clinical experience with molding powders orintact implants of this polymer (1, 1
13、2). The shape and size ofwear particles of this polymer and other implanted highpolymers have been suggested as factors in elicited tissuereaction (1, 11, 13). Therefore, care should be exercised not toconstrue this specification for applications where particulatedebris may be anticipated.4. Physica
14、l Property Requirements4.1 Molding and Extrusion Powders:4.1.1 PTFE Polymer Molding and extrusion powdersused for fabrication of implant configurations shall be virginproduct which conform to Specification D 1457.4.2 PTFE Standard Shapes:1This specification is under the jurisdiction of ASTM Committe
15、e F-4 on Medicaland Surgical Materials and Devicesand is the direct responsibility of SubcommitteeF04.16 on Biocompatibility.Current edition approved May 10, 2000. Published August 2000. Originallypublished as F 754 83. Last previous edition F 754 88 (95).2The boldface numbers in parentheses refer t
16、o the list of references at the end ofthis specification.3Annual Book of ASTM Standards, Vol 08.01.4Annual Book of ASTM Standards, Vol 08.02.5Annual Book of ASTM Standards, Vol 08.03.6Annual Book of ASTM Standards, Vol 13.01.1Copyright ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, U
17、nited States.4.2.1 Standard shapes such as molded sheet, rod, or tubeshall have been prepared from virgin molding or extrusionmaterials which meet Specification D 1457.4.2.2 PTFE molded sheet shall comply with Type I, Grade I,Class A requirements in Specification D 3293.4.2.3 PTFE rod and tube shall
18、 comply with Type I, Grade I,Class D specifications in Specification D 1710. Material pur-chased for conversion into final implant shapes may meetClasses A, B, C, or D by vendor and vendee agreement.4.3 Surface ContaminationThe surface of a fabricatedshape shall not contain particles of residue of d
19、iameter greaterthan 300 m. The concentration of visible particles under 83magnification shall not be greater than 10 particles per 400cm2.4.4 Physical properties for other than standard shapes arenot encompassed by this specification and must be addressedby appropriate performance standards for give
20、n configurations.5. Chemical Property Requirements5.1 Carbon Tetrachloride ExtractionPTFE sampled inaccordance with Practice D 1898, from packaged-for-salestock shall be extracted with carbon tetrachloride by themethod described in Annex A1.5.1.1 Extractable HydrocarbonsThe absence of extract-able h
21、ydrocarbons shall be demonstrated by infrared analysisof the carbon tetrachloride extract using the methodology andacceptance criteria described in Annex A1.5.1.2 AppearanceA sample should be obtained frompackaged-for-sale stock and examined under daylight condi-tions with the naked eye immediately
22、following carbon tetra-chloride extraction as described in Annex A1. This samplewhile still wet with carbon tetrachloride shall not be apparentlychanged in size or consistency. When dried for4hina100Cair-circulating oven, the appearance of the extracted polymersample shall be unchanged as compared t
23、o an unextractedspecimen.5.2 Extraction with Distilled WaterPTFE sampled frompackaged-for-sale stock shall be extracted with distilled waterby the methodology described in Annex A2.5.2.1 Extractable ElectrolytesThe resistivity of the wateras measured by a resistivity conductivity meter shall be grea
24、terthan 0.05 MVcm.5.2.2 AppearanceWhen examined by unaided vision indaylight, the appearance of PTFE sampled from stock imme-diately following water extraction shall be unchanged exceptfor being obviously wet with water. When dried for4hat100C in an air-circulating oven the appearance shall beunchan
25、ged from pre-extraction appearance.6. Biocompatibility6.1 Extractables Under Simulated and Accelerated In VivoExposureThe polymer sampled from packaged-for-salestock shall be tested under the general methodology andPractices F 749 and F 750 with specific conditions and criteriadescribed in Annex A3.
26、6.2 Acute Biocompatibility RequirementsThe polymersampled from packaged-for-sale stock shall show no cyto-pathic effect when evaluated by a tissue culture test using directcontact of specimen with cell layer technique (13, 14) orASTM Practice F 813 and Test Method F 895.6.3 Chronic Biocompatibility
27、RequirementsVendor andvendee agreement may utilize the large, long-term and benignanimal and clinical history of this generic class of polymer asequivalent to Practice F 748 and Practice F 981 certification.7. Sterility7.1 Fabricated configurations of PTFE are thermally stableto indefinite exposure
28、at 200C. The fabricated polymer shall,after sterilization, pass the USP Sterility Test (15). Therefore,primary or repetitive sterilization by reliable steam autoclavetechnique is suggested. An alternative sterilization technique ofusing ethylene oxide may be adopted with due considerationfor degassi
29、ng rates for the particular specimen configuration.Sterilization by irradiation may cause molecular degradation ofthe polymer above certain radiation levels. Depending on theintended use of the implant, this molecular degradation couldaffect its mechanical and biocompatible properties.8. Keywords8.1
30、 high polymer; polymer; polytetrafluoroethylene; PTFE;surgical implantANNEXES(Mandatory Information)A1. INFRARED ANALYSIS OF HYDROCARBONS EXTRACTABLE IN CARBON TETRACHLORIDEA1.1 Stir at least1gofchopped sample, all of which passesa No. 40 mesh screen, for 30 min with 7-mL of reagent-gradecarbon tetr
31、achloride. When decanted, the carbon tetrachlorideshall be clear and colorless.A1.2 Perform infrared analysis with a Beckman InfraredSpectrophotometer IR-8, with Beckman Cell Part No. 580012,or equivalent.A1.2.1 The requirements of this analysis shall be satisfiedwhen transmission between 3 and 4 m
32、is essentially 100 % forthe reagent grade control and at least 95% of that of the controlscan for carbon tetrachloride in which the chopped sample wasstored.F 7542A2. EXTRACTION WITH WATER FOR ELECTROLYTESA2.1 The specimens shall be cubes or rectangles with noedge dimension greater than 1 cm. The to
33、tal specimen weightshall be 10 6 1g.A2.2 Place the specimens in a suitable container, such asa100-cm3suction flask, along with 50 mL of distilled water.Store the flask 48 h at ambient temperature.A2.3 After 48 h, decant the water. The water shall remainclear and colorless. The extractable electrolyt
34、e requirementsshall be satisfied when the resistivity of the water is greaterthan 0.05 MVcm.A3. INFRARED ANALYSIS FOR ORGANIC SUBSTANCES EXTRACTABLE UNDER ACCELERATED,SIMULATED IN VIVO CONDITIONS (4)A3.1 Use a total sample size of 150 squares each measuring1 by 5 by 5 mm or a sample size having equi
35、valent volume andsurface area.A3.2 Extracting MediaPrepare pseudo-extracellular fluidby dissolving 6.68 g of NaCl, 2.50 g of NaHCO3, 0.174 g ofK2HPO4, and 0.220 g of KCL in 1000 mL of distilled water.A3.3 Extraction TechniquePlace the sample in a monelmetal screen cage and submerge in 250 mL of the
36、extractingmedia. Conditions of extraction shall be 66 h at 96C.A3.4 Infrared AnalysisAfter extraction is complete, de-cant the pseudo-extracellular fluid. Its color shall be unchangedfrom pre-extraction. Extract the decanted liquid with 14 mL ofreagent-grade carbon tetrachloride in a separatory funn
37、el.Separate the carbon tetrachloride and dry with anhydrousMgSO4. Compare a sample of the dried extractant sample withfresh reagent-grade carbon tetrachloride using an infraredspectrophotometer (Beckman IR-8 spectrophotometer orequivalent, Beckman Part No. 580012 cell, or equivalent). Ifhydrocarbons
38、 are present infrared absorption will occur be-tween 3 and 4 m.A3.4.1 The requirements of this test shall be satisfied whentransmission between 3 and 4 m is essentially 100% forreagent-grade carbon tetrachloride and at least 95% of that forthat of the control scan for the carbon tetrachloride extrac
39、t.APPENDIXES(Nonmandatory Information)X1. STATEMENT OF RATIONALEX1.1 This specification was established to provide guid-ance in the testing of polytetrafluorethylene intended for use inmedical device applications. It recommends test methods forthe measurement of chemical, physical and mechanical pro
40、p-erties of unfabricated and fabricated forms. Tests should beselected according to end-use applications. It is intended thatbiocompatibility be established on the finished product by theappropriate procedures, after it has gone through all processingsteps.X1.2 The scope section of this document def
41、ines the term“PTFE” and limits the specific scope of the document tofabricated sheet, tube, and rod shapes. It further makes clearthat the specification does not apply to specific surgicalimplants that would be subject to appropriate specific end-useperformance standards. This section emphasizes the
42、 extraordi-nary chemical and thermal stability and inherent absence ofadditives in PTFE; these factors are no doubt responsible forthe large bibliography of successful implant use for thispolymer in the absence of any previous implant grade specifi-cation guidance.X1.3 The significance section sets
43、out the capability of thisstandard by ensuring consistent and reproducible behavior.Section 3.2 explains the caution against construing this speci-fication for applications where particulate debris may beanticipated.X1.4 In 4.1 the specific raw polymer properties consistentwith the scope and intent
44、of this specification are defined interms of existing ASTM specifications so that the raw polymerswill be virgin products providing the highest purity availableunder current manufacturing technology. Similarly, 4.2 relatesthe finished shape physical properties consistent with the scopeand objectives
45、 of this standard specification to existing ASTMspecifications for such standard shapes. These requirementswould provide the superior properties for such shapes availablewith current fabrication technology.X1.5 Section 5 provides appearance and extractable criteriafor PTFE-fabricated shapes sampled
46、from packaged-for-salestock to establish the absence of extractable organic or elec-trolytic contaminants that may have contaminated the productduring its preparation and packaging. These tests would thenF 7543signal the need for review of manufacturing protocol todetermine where a breach may have o
47、ccurred of the GoodManufacturing Practices regulations detailed in the U.S. Codeof Federal Regulations.X1.6 Section 6 prescribes specific biocompatibility assaysthat may be readily conducted on samples from packaged-for-sale stock to ensure biocompatibility. Although ASTM Prac-tices F 749 and F 750
48、are the primary references for theevaluation of extractables under accelerated simulated in vivoexposure, more stringent test conditions are recommended inAnnex A3 which the unique chemical and thermal stability andabsence of additives of PTFE make feasible. These morestringent test conditions have
49、provided assurance of safe andeffective long-term in vivo implant performance for fabricatedPTFE (1, 12).X1.7 Finally, in Section 7 factors relating to mode ofsterilization and reference to the USP sterility test protocols aredescribed.X2. BiocompatibilityX2.1 No known surgical implant material has ever beenshown to be completely free of adverse reactions in the humanbody. However, long term clinical experience of use of specificcompositions and formations of this material referred to in thisstandard has shown that an acceptable level of biologicalresponse can
