ASTM F2695-2007 Standard Specification for Ultra-High Molecular Weight Polyethylene Powder Blended With Alpha-Tocopherol (Vitamin E) and Fabricated Forms for Surgical Implant Appli.pdf

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1、Designation: F 2695 07Standard Specification forUltra-High Molecular Weight Polyethylene Powder BlendedWith Alpha-Tocopherol (Vitamin E) and Fabricated Forms forSurgical Implant Applications1This standard is issued under the fixed designation F 2695; the number immediately following the designation

2、indicates the year oforiginal adoption or, in the case 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 covers ultra-high

3、molecular weightpolyethylene (UHMWPE) powder blended with alpha-tocopherol (vitamin E) intended for use in surgical implants.1.2 The requirements of this specification apply to alpha-tocopherol-containing UHMWPE in two forms. One is virginpolymer powder blended with alpha-tocopherol prior to con-sol

4、idation (Section 4). The second is any form fabricated fromthis blended, alpha-tocopherol-containing powder from whicha finished product is subsequently produced (Section 5). Thisspecification does not apply to finished or semi-finishedproducts that are doped with vitamin E after consolidation.1.3 A

5、side from blending with alpha-tocopherol, the provi-sions of Specifications F 648 and D 4020 apply. Specialrequirements detailed in this specification are added to describepowders containing alpha-tocopherol that will be used insurgical implants. This specification addresses material char-acteristic

6、s and does not apply to the packaged and sterilizedfinished implant. This specification also does not apply toUHMWPE materials extensively crosslinked by gamma andelectron beam sources of ionizing radiation.1.4 The following precautionary caveat pertains only to thefabricated forms portion, Section

7、5, of this specification. Thisstandard does not purport to address all of the safety concerns,if any, associated with its use. It is the responsibility of the userof this standard to establish appropriate safety and healthpractices and determine the applicability of regulatory limita-tions prior to

8、use.2. Referenced Documents2.1 ASTM Standards:2D 648 Test Method for Deflection Temperature of PlasticsUnder Flexural Load in the Edgewise PositionD 790 Test Methods for Flexural Properties of Unreinforcedand Reinforced Plastics and Electrical Insulating MaterialsD 1898 Practice for Sampling of Plas

9、tics3D 4020 Specification for Ultra-High-Molecular-WeightPolyethylene Molding and Extrusion MaterialsF 619 Practice for Extraction of Medical PlasticsF 648 Specification for Ultra-High-Molecular-Weight Poly-ethylene Powder and Fabricated Form for Surgical Im-plantsF 748 Practice for Selecting Generi

10、c Biological Test Meth-ods for Materials and DevicesF 749 Practice for Evaluating Material Extracts by Intracu-taneous Injection in the RabbitF 756 Practice for Assessment of Hemolytic Properties ofMaterialsF 763 Practice for Short-Term Screening of Implant Mate-rialsF 813 Practice for Direct Contac

11、t Cell Culture Evaluation ofMaterials for Medical DevicesF 895 Test Method for Agar Diffusion Cell Culture Screen-ing for CytotoxicityF 981 Practice for Assessment of Compatibility of Bioma-terials for Surgical Implants with Respect to Effect ofMaterials on Muscle and Bone2.2 ISO Standards:ISO 3451-

12、1 PlasticsDetermination of Ash, Part 1: Gen-eral Methods4ISO 10993 Biological Evaluation of Medical Devices, Parts11243. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 crosslinkingthe process by which ionizing irradia-tion produces chemical bonds between two UHMWPE mol-ecules.3.

13、1.2 extensively crosslinked UHMWPEUHMWPE mate-rial that has been subjected to total doses of gamma and/orelectron beam ionizing irradiation greater than 40 kGy.1This specification is under the jurisdiction of ASTM Committee F04 onMedical and Surgical Materials and Devices and is the direct responsib

14、ility ofSubcommittee F04.11 on Polymeric Materials.Current edition approved Dec. 1, 2007. Published December 2007.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to th

15、e standards Document Summary page onthe ASTM website.3Withdrawn.4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United S

16、tates.Copyright by ASTM Intl (all rights reserved); Fri Jan 16 01:31:03 EST 2009Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.3.1.3 fabricated formany bulk shape of UHMWPE, fab-ricated from the virgin polymer powder, used during theprocess o

17、f fabricating surgical implants prior to crosslinking,packaging, and sterilization. A fabricated form includes asemi-finished rod or sheet as well as a direct compressionmolded component.3.1.4 generic propertythat property which is determinedsolely by the chemical composition and structure of the vi

18、rginpolymer.3.1.5 ionizing irradiationgamma ray or high energy elec-tron irradiation sources.3.1.6 virgin polymer powderthe form of UHMWPE asobtained from the powder manufacturer and prior to fabricationinto a bulk shape.4. Alpha-Tocopherol-Blended UHMWPE PowderRequirements4.1 Generic Properties:4.1

19、.1 The virgin polymer shall be a homopolymer of ethyl-ene in accordance with Specification D 4020.4.1.2 The resin type and solution viscosity number require-ments are listed in Table 1 of Specification F 648.4.2 Nongeneric Properties:4.2.1 When a 300 g sample is prepared and viewed inaccordance with

20、 section 7.1.2 of Specification F 648, thereshall be no more particles of extraneous matter than thatspecified in Table 1 of Specification F 648.4.2.2 To promote uniformity between different lots of poly-mer powder, concentration limits for trace elements have beenestablished and are listed in Table

21、 1 of Specification F 648.4.2.3 When determined as described in ISO 3451-1, themean ash of duplicate samples shall not exceed the limitsestablished in Table 1 of Specification F 648.4.3 Compositional Requirements:4.3.1 Only alpha-tocopherol (certified pharmaceuticalgrade) is to be blended with the v

22、irgin polymer powder.4.3.1.1 The alpha-tocopherol content in the blended powdermay be based on agreement between the vendor and purchaser.4.3.1.2 When measured based on agreement between thevendor and purchaser, the alpha-tocopherol content added tothe powder shall be reported in units of ppm and pe

23、rcent mass.4.3.1.3 Uniformity of the alpha-tocopherol in the blendedpowder will be measured based on agreement between thevendor and the purchaser.4.3.1.4 No other stabilizers or processing aids are to beadded to the virgin polymer powder.5. Alpha-Tocopherol-Blended UHMWPE FabricatedForm Requirement

24、s5.1 Compositional Requirements:5.1.1 Only alpha-tocopherol-blended powder, specified inSection 4, is to be used to produce the fabricated form.5.1.1.1 The alpha-tocopherol content in the fabricated formmay be based on agreement between the vendor and purchaser.5.1.1.2 When measured based on agreeme

25、nt between thevendor and purchaser, the alpha-tocopherol content used toproduce the fabricated form shall be reported in units of ppmand percent mass.5.1.2 Uniformity of the alpha-tocopherol in the fabricatedform shall be measured based on agreement between thevendor and the purchaser.5.1.3 No other

26、 stabilizers or processing aids are to be addedto the alpha-tocopherol-blended polymer powder during manu-facture of the fabricated form.5.2 Physical Requirements:5.2.1 Foreign Matter Requirements:5.2.1.1 When 3200 cm2is evaluated according to section7.2.2 of Specification F 648, there shall be no m

27、ore than 10particles of extraneous matter visible on the surface whenvisually inspected by normal or corrected vision.5.2.2 Morphology Requirements:5.2.2.1 When evaluated according to Annex 2 of Specifica-tion F 648, the calculated Morphology Index (MI) shall bereported.5.3 Mechanical Requirements:5

28、.3.1 UHMWPE in fabricated form from which implantsshall be made shall meet the requirements listed in Table 2 ofSpecification F 648.5.3.2 The following mechanical tests may be conductedbased on agreement between the vendor and purchaser: (1)Deflection temperature; Test Method D 648 (1.8 MPa); (2)Fle

29、xural modulus; Test Methods D 790 (secant, 2 % offset).6. Sampling6.1 Where applicable, the requirements of this specificationshall be determined for each lot of powder and fabricated formby sampling sizes and procedures according to PracticeD 1898, or as agreed upon between the purchaser and seller

30、.7. Biocompatibility7.1 No known surgical implant material has ever beenshown to be completely free of adverse reactions in the humanbody. However, published studies (1-5)5of specific formula-tions of alpha-tocopherol doped UHMWPE have shown that anacceptable level of biological response can be expe

31、cted. Virgin(undoped) UHMWPE has been shown to produce a well-characterized level of biological response following long termclinical use. The clinical history for virgin UHMWPE indicatesan acceptable level of biological response in the applications inwhich the undoped material has been utilized. Whe

32、n newapplications of the material, or modification to the material orphysical forms of the materials are being contemplated (suchas, blending with alpha-tocopherol), the recommendations ofISO 10993, Parts 112 and Practice F 748 should be consid-ered and testing considered as described in Practices F

33、 619,F 749, F 756, F 763, F 813, and F 981 as well as Test MethodF 895.8. Keywords8.1 alpha-tocopherol; fabricated forms; powdered form;ultra-high molecular weight polyethylene; vitamin E5The boldface numbers in parentheses refer to the list of references at the end ofthis standard.F2695072Copyright

34、 by ASTM Intl (all rights reserved); Fri Jan 16 01:31:03 EST 2009Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.APPENDIX(Nonmandatory Information)X1. RATIONALEX1.1 This specification is intended to describe the proper-ties required and the pr

35、ocedures to be followed in testingunirradiated raw materials of UHMWPE blended with alpha-tocopherol for medical implant applications. This specificationdoes not purport to address the testing that is needed forimplants that are fabricated from the raw materials specifiedherein.X1.2 Alpha-tocopherol

36、 is a biocompatible stabilizer ofpolyolefins (1-6) and is intended to reduce oxidative degrada-tion during processing, radiation processing, shelf life storage,and in vivo exposure of UHMWPE. Several laboratory studieshave demonstrated that alpha-tocopherol will stabilize irradi-ated UHMWPE from acc

37、elerated aging conditions intended tosimulate a variety of severe oxidative challenges (7-12).Human clinical use of implants fabricated from alpha-tocopherol blended UHMWPE is reported to have begun in2004. At present, the extent to which alpha-tocopherol willhelp stabilize UHMWPE implants from in v

38、ivo oxidation hasnot yet been determined.X1.3 While beneficial for oxidative stability, levels ofalpha-tocopherol $1000 ppm may later interfere with subse-quent radiation crosslinking steps (7, 10) during subsequentstages of the implant manufacturing process. With 1000 ppm ofalpha-tocopherol, Oral e

39、t al. have reported an average reduc-tion of 17 % in crosslink density following a dose of 100 kGy(7). On the other hand, levels of alpha tocopherol in the range125 to 500 ppm appear to be effective for stabilization ofUHMWPE, although the level of stabilization depends uponthe dose of radiation and

40、 the type of oxidative challenge (7, 11,12). Thus, crosslinking will be a function of both the alpha-tocopherol content and the radiation dose, both of which maydepend upon the choice of the manufacturer. Consequently, thisstandard is not intended to specify a minimum alpha-tocopherol content for un

41、irradiated raw materials that willsubsequently be used to fabricate orthopedic implants. Devicetesting is recognized to be crucial for UHMWPE implants, butis beyond the scope of this standard specification.X1.4 The current standard specifies alpha-tocopherol con-tent to be reported based on the mass

42、 percentage of antioxidantblended with the virgin resin powder prior to consolidation.Experimental techniques, including Fourier transform infraredspectroscopy and HPLC (4, 7), have been proposed in theliterature for characterizing the content of alpha-tocopherol,and its by-products, in consolidated

43、 UHMWPE. At presentthese research techniques have not been standardized. In thefuture, when quantification techniques for UHMWPE contain-ing alpha-tocopherol have been standardized, it is expected thatthe current specification will be updated to include morespecific details regarding appropriate tes

44、t methodologies.REFERENCES(1) Wolf, C., Lederer, K., Pfragner, R., Schauenstein, K., Ingolic, E., andSiegl, V., “Biocompatibility of Ultra-High Molecular Weight Polyeth-ylene (UHMW-PE) Stabilized with Alpha-Tocopherol Used for JointEndoprostheses Assessed In Vitro,” Journal of Materials Science, Feb

45、3, 2007.(2) Wolf, C., Lederer, K., Bergmeister, H., Losert, U., and Bock, P.,“Animal Experiments with Ultra-High Molecular Weight Polyethylene(UHMW-PE) Stabilized with Alpha-Tocopherol Used for ArticulatingSurfaces in Joint Endoprostheses,” Journal of Materials Science,17(12), Dec 2006, pp. 13411347

46、.(3) Reno, F., Cannas, M., “UHMWPE and Vitamin E Bioactivity: AnEmerging Perspective,” Biomaterials, 27(16), Jun 2006, pp.30393043.(4) Wolf, C., Lederer, K., and Muller, U., “Tests of Biocompatibility ofAlpha-Tocopherol with Respect to the Use as a Stabilizer in UltrahighMolecular Weight Polyethylen

47、e for Articulating Surfaces in JointEndoprostheses,” Journal of Materials Science, 13(7), Jul 2002, pp.701705.(5) Shibata, N., Kurtz, S. M., and Tomita, N., “Advances of MechanicalPerformance and Oxidation Stability in Ultrahigh Molecular WeightPolyethylene for Total Joint Replacement: Highly Crossl

48、inked anda-Tocopherol Doped,” J Biomed Sci Eng., 1(1), 2006, pp. 107112.(6) Al-Malaika, S., “Perspectives in Stabilization of Polyolefins,” AdvPolym Sci., 169, 2004, pp. 121150.(7) Oral, E., Greenbaum, E. S., Malhi,A. S., Harris, W. H., and Muratoglu,O. K., “Characterization of Irradiated Blends ofA

49、lpha-Tocopherol andUHMWPE,” Biomaterials, 26(33), Nov 2005, pp. 66576663.(8) Wolf, C., Macho, C., and Lederer, K., “Accelerated Aging Experi-ments with Crosslinked And Conventional Ultra-High MolecularWeight Polyethylene (UHMW-PE) Stabilized with Alpha-Tocopherolfor Total Joint Arthroplasty,” Journal of Materials Science, 17(12),Dec 2006, pp. 13331340.(9) Wolf, C., Krivec, T., Blassnig, J., Lederer, K., and Schneider, W.,“Examination of the Suitability ofAlpha-Tocopherol as a Stabilizer forUltra-High Molecular Weight Polyethylene Used for ArticulatingSurfaces in Joint