1、Designation: F 2458 05Standard Test Method forWound Closure Strength of Tissue Adhesives and Sealants1This standard is issued under the fixed designation F 2458; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revi
2、sion. 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 test method covers a means for comparison ofwound closure strength of tissue adhesives used to help securethe apposition
3、of soft tissue. With the appropriate choice ofsubstrate, it may also be used for purposes of quality control inthe manufacture of medical devices used as tissue adhesives.1.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility
4、 of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 907 Terminology of AdhesivesE4 Practices for Force Verification of Testing Machines2.2 Other Docume
5、nt:American Association of Tissue Banking, Standards forTissue Banking33. Terminology3.1 DefinitionsMany terms in this test method are definedin Terminology D 907.3.1.1 tissue adhesiveany material used as a medicaldevice to help secure the apposition of two wound edges oropposed soft tissues.3.1.2 t
6、issue sealanta surface coating with adequate adhe-sive strength to prevent leakage of body fluids.3.1.3 cohesive strengthinternal strength of the adhesive.3.1.4 adhesive strengththe strength of the tissue adhesive/substrate interface.3.1.5 cohesive failurefailure of the internal adhesivebond.3.1.6 a
7、dhesive failurefailure of the adhesive/substratebond.3.1.7 substrate failurefailure of the tissue substrate.4. Significance and Use4.1 Materials and devices that function at least in part byadhering to living tissues are finding increasing use in surgicalprocedures either as adjuncts to sutures and
8、staples, or as frankreplacements for those devices in a wide variety of medicalprocedures. While the nature and magnitude of the forcesinvolved varies greatly with indication and with patient specificcircumstances, all uses involve to some extent the ability of thematerial to resist imposed mechanic
9、al forces. Therefore, themechanical properties of the materials, and in particular theadhesive properties, are important parameters in evaluatingtheir fitness for use. In addition, the mechanical properties of agiven adhesive composition can provide a useful means ofdetermining product consistency f
10、or quality control or as ameans for determining the effects of various surface treatmentson the substrate prior to use of the device.4.2 The complexity and variety of individual applicationsfor tissue adhesive devices, even within a single indicated use(surgical procedure, which itself may vary depe
11、nding onphysical site and clinical intention) is such that the results of asingle tensile strength test is not suitable for determiningallowable design stresses without thorough analysis and under-standing of the application, adhesive behaviors, and clinicalindications.4.3 This test method may be us
12、ed for comparing adhesivesor bonding processes for susceptibility to fatigue, mode offailure, and environmental changes, but such comparisons mustbe made with great caution since different adhesives mayrespond differently to varying conditions.4.4 A correlation of the test method results with actual
13、adhesive performance in live human tissue has not beenestablished.5. Apparatus5.1 Testing MachineA testing machine of the constant-rate-of-crosshead-movement type and comprising essentiallythe following:5.1.1 Fixed MemberA fixed or essentially stationarymember carrying one grip.1This test method is
14、under the jurisdiction of ASTM Committee F04 on Medicaland Surgical Materials and Devices and is the direct responsibility of SubcommitteeF04.15 on Material Test Methods.Current edition approved Mar. 1, 2005. Published March 2005.2For referenced ASTM standards, visit the ASTM website, www.astm.org,
15、orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American Association of Tissue Banks (AATB), 1320 OldChain Bridge Rd., Suite 450, McLean, VA 22101.1Copyright ASTM
16、International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.1.2 Movable MemberA movable member carrying asecond grip.5.1.3 GripsGrips for holding the test specimen betweenthe fixed member and the movable member of the testingmachine can be either the fixed or
17、 self-aligning type. Grippingpressure should be adjustable to prevent damage to thesubstrate and the use of sandpaper or plastic scrubbing padsbetween the gripping surfaces and the substrate is recom-mended to help prevent slippage.5.1.3.1 Fixed grips are rigidly attached to the fixed andmovable mem
18、bers of the testing machine. When this type ofgrip is used, extreme care should be taken to ensure that the testspecimen is inserted and clamped so that the long axis of thetest specimen coincides with the direction of pull through thecenterline of the grip assembly.5.1.3.2 Self-aligning grips are a
19、ttached to the fixed andmovable members of the testing machine in such a manner thatthey will move freely into alignment as soon as any load isapplied so that the long axis of the test specimen will coincidewith the direction of the applied pull through the center line ofthe grip assembly. The speci
20、mens should be aligned as per-fectly as possible with the direction of pull so that no rotarymotion that may induce slippage or damage to the sample willoccur in the grips; there is a limit to the amount of misalign-ment self-aligning grips will accommodate.5.1.4 Drive MechanismA drive mechanism for
21、 impartingto the movable member a uniform, controlled velocity withrespect to the stationary member, with this velocity to beregulated as specified in 8.3.5.1.5 Load IndicatorA suitable load-indicating mecha-nism capable of showing the total tensile load carried by thetest specimen when held by the
22、grips. This mechanism shall beessentially free of inertia lag at the specified rate of testing andshall indicate the load with an accuracy of 61 % of theindicated value, or better. The accuracy of the testing machineshall be verified in accordance with Practices E4.5.2 Temperature-controlling Equipm
23、entCapable of main-taining the test temperature to 62C. If ambient laboratoryconditions are employed, the same degree of control is re-quired.6. Test Substrate6.1 For Comparative TestingEither fresh or frozen splitthickness porcine skin graft may be used.6.1.1 Frozen split thickness porcine skin tha
24、t has beenaseptically prepared is available commercially and is preferreddue to ease of use and the potential for more consistentproperties. It should be thawed according to the manufacturersinstructions prior to use. Unused graft may be kept at 2 to 8Cfor up to two weeks after thawing.6.1.2 If fres
25、h skin is chosen, it should be prepared accordingthe method in Appendix X1.6.2 For Application Specific TestingThe grips of the testmachine must be able to hold the tissue without having thetissue slip or be crushed by the grips. Some tissue (liver, lung)may not be suitable for this test.6.2.1 The s
26、trength of any adhesive is highly dependent onthe test substrate or adherend. For a specific application, thepreferred substrate is freshly harvested tissue from the targetorgan of a domestic food animal. Tissue from bovine, porcine,or ovine origin is preferred due to wide availability and the factt
27、hat relatively large samples of tissue can be harvested from asingle source. Ideally, the tissue should be used within 24 h ofharvest and should be kept between 5 and 10C prior to testingif it cannot be used immediately after harvesting. Storage andhandling of tissue samples should be carried out ac
28、cording tothe guidelines set forth in Standards for Tissue Banking by theAmerican Association of Tissue Banks. The specimens shouldbe brought to the test temperature or other prescribed tempera-ture (such as body temperature) prior to application of theadhesive.6.2.2 Fixed tissue should not be used
29、since it has beendemonstrated that fixatives cause large alterations in themechanical properties of the tissue and it is probable that theadhesive strength would be affected as well.6.2.3 If the target organ is of a size or geometry that doesnot allow fabrication of test samples as shown in Fig. 1,
30、a tissueof similar origin but larger size should be used. For example, ifthe intended indication is for anastomosis of small bloodvessels, a larger vessel should be substituted.FIG. 1 Test Specimen Top ViewF24580526.2.4 The thickness of the tissue sample should not exceed5 mm.6.3 For Quality Control
31、 Testing:6.3.1 For testing that is undertaken as part of a qualitycontrol process in the manufacturing of a tissue adhesivedevice, the use of freshly harvested tissue is highly inconve-nient and may also lead to unacceptable variation in the testresults, especially if the failure occurs in the adher
32、end (sub-strate failure). Since the purpose of quality control testing is todemonstrate consistency in the device, substitution of a modelsubstrate is preferred so long as it is demonstrated that theadhesive bonds to the adherend. If the test is intended togenerate data on the cohesive strength of t
33、he device, anymetallic or polymeric material is acceptable so long as it hasbeen demonstrated that the adhesive bonds to the adherend andthat failure is substantially cohesive (90 % by area) and notadhesive. For adhesive quality control testing, it is recom-mended that test results for any substrate
34、 of non-biological orfixed tissue origin be correlated to testing previously done onfresh tissue substrates prior to acceptance of the procedure.7. Test Specimen7.1 The wound strength test specimen is shown in Fig. 1.Two substrate samples are required for each test specimen.7.2 A template of the cor
35、rect dimensions should be used. Asharp scalpel or similar device should be used to cut thesubstrate material.7.3 Sample width should be 2.5 6 0.1 cm.7.4 Sample length should be 10 6 0.2 cm.7.5 Number of Test SpecimensTest at least 10 specimensof each type. Tissue substrates tend to give high varianc
36、es andwill require more samples to attain a reasonable estimate of themean strength.8. Specimen Preparation8.1 Tissue Preparation:8.1.1 Tissue substrate materials should be kept moist at alltimes with phosphate buffered saline (PBS).8.1.2 The substrate will be cut to the dimensions given inSection 7
37、 using a template and a fresh scalpel blade or a cutterfabricated to the required dimensions.8.1.3 Wrap the tissue with gauze soaked in phosphatebuffered saline (PBS), place in a plastic bag, and place them ina water bath or environmental chamber at 37C.8.2 Preparation of the Adhesive Bond:8.2.1 Rem
38、ove two tissue samples from the plastic bag andpat the surfaces of the tissue dry with fresh gauze.8.2.2 Orient the samples as shown in Fig. 1 with the endstouching. A non-slip surface should be used to help hold thesamples in place during adhesive application.8.2.3 Prepare the adhesive and use acco
39、rding to the instruc-tions for use (IFU). For topical adhesives, care should be takento ensure that they are tested topically (as a bridge) as intendedfor clinical use and measures (petroleum jelly between edgesand the under surface and sides) should be taken to ensure theadhesive does not seep betw
40、een the wound edges and providean interface bond. An interface bond may give highly variableresults. Adhesive thickness is also an important parameter totry and control and will also lead to tensile strength variation.By keeping the adhesive within the required bond area (0.5 cmon either side of the
41、 join line), thickness may be controlled byapplying a predetermined volume of adhesive.8.3 After the adhesive has cured, measure and record thewidth and length of the adhesive bond to within 0.05 cm.8.4 Re-cover the tissue with gauze soaked in PBS, replacethe sample in a plastic bag, and return it t
42、o the constanttemperature environment. Adhesives should be allowed to cureaccording to the IFU and for a minimum of 15 min.9. Procedure9.1 Condition the test specimens for definite periods of timeunder specified, controlled conditions before testing if desired.Recommended conditions for tissue adhes
43、ives intended forinternal applications are 37C in PBS. For adhesives intendedfor external topical use, recommended conditions are 30C and50 % relative humidity. For quality control testing, the recom-mended conditions are 23C and 50 % relative humidity. Afterconditioning, it is recommended that all
44、specimens be stabi-lized at the test temperature for 15 min before testing if the testtemperature is different from the conditioning temperature.Tissue samples must be kept moist with PBS throughout theprocess to prevent shrinkage due to drying.9.2 Place the test specimens in the grips of the testin
45、gmachine so that the applied load coincides with the long axis ofthe specimen. The distance from the grip to the mid-line ofeach sample should be 5 cm, with the remaining 5 cm beingfirmly held with the grips. Load the specimen to failure at aconstant cross-head speed of 50 mm/min.9.3 Record the time
46、 from application to testing (cure time),force at failure (maximum force required to disrupt substrate),and the type of failure (percentage cohesive, adhesive, orsubstrate failure based on observation of the bond area).10. Calculations10.1 Calculate the median, mean, and standard deviation ofthe pea
47、k load at failure (Newtons (N) for each group ofsamples.11. Report11.1 Report the following:11.1.1 Complete identification of the adhesive tested, in-cluding type, source, date manufactured, manufacturers lotnumber, and expiration date.11.1.2 Complete identification of the substrate used, itslength,
48、 width, and thickness, and any method used to clean orprepare the surface prior to bonding.11.1.3 Amount of adhesive applied.11.1.4 Method of adhesive application.11.1.5 Ambient conditions at time of bonding (temperatureand humidity).11.1.6 Length and width of adhesive bond.11.1.7 Conditioning of sp
49、ecimen prior to testing.11.1.8 Maximum, minimum, median, mean, and standarddeviation for the peak loads measured.11.1.9 Number of specimens tested.11.1.10 Type of failure. This should include estimatedpercentages of cohesive failure in the adhesive, apparentfailure in adhesion, and failure in the adherend (substrate).F245805311.1.11 Test temperature employed.12. Precision and Bias12.1 A precision and bias statement does not exist for thistest method because round robin testing has not yet beenperformed.13. Keywords13.1 adhesive strength; cohesive strength; t
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