1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 18192-2:2010Implants for surgery Wear oftotal intervertebral spinal discprosthesesPart 2: Nucleus replacementsBS ISO 18192-2:2010 BRITISH STANDARDNational forewordThis Bri
2、tish Standard is the UK implementation of ISO 18192-2:2010.The UK participation in its preparation was entrusted to TechnicalCommittee CH/150/5, Surgical Implants - Osteosynthesis and spinaldevices.A list of organizations represented on this committee can beobtained on request to its secretary.This
3、publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. BSI 2010ISBN 978 0 580 66227 0ICS 11.040.40Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under th
4、e authority of theStandards Policy and Strategy Committee on 31 July 2010Amendments issued since publicationDate Text affectedBS ISO 18192-2:2010Reference numberISO 18192-2:2010(E)ISO 2010INTERNATIONAL STANDARD ISO18192-2First edition2010-06-15Implants for surgery Wear of total intervertebral spinal
5、 disc prostheses Part 2: Nucleus replacements Implants chirurgicaux Usure des prothses totales de remplacement des disques intervertbraux lombaires Partie 2: Remplacements nuclaires BS ISO 18192-2:2010ISO 18192-2:2010(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with
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8、 care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. COPYRIGHT PROTECTED DOCUMENT ISO 2010 All rights reserved. Unless otherwise specified
9、, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case p
10、ostale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2010 All rights reservedBS ISO 18192-2:2010ISO 18192-2:2010(E) ISO 2010 All rights reserved iiiContents Page Foreword iv 1 Scope1 2 Normative references1 3
11、 Terms and definitions .1 4 Principle2 5 Reagents and materials 2 5.1 Fluid test medium2 5.2 Test and control specimens.3 6 Apparatus.3 6.1 Testing machine 3 6.2 Motion restraint system3 6.3 Means of aligning and positioning 3 6.4 Test chamber .4 6.5 Temperature control system 4 7 Cycle limit.4 8 Pr
12、ocedure.4 9 Test report5 10 Disposal of test specimen 6 Annex A (informative) Statement of rationale for test methods.7 Bibliography8 BS ISO 18192-2:2010ISO 18192-2:2010(E) iv ISO 2010 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of n
13、ational standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. Inter
14、national organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the
15、 rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by
16、 at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 18192-2 was prepared by Technical Committee I
17、SO/TC 150, Implants for surgery, Subcommittee SC 5, Osteosynthesis and spinal devices. ISO 18192 consists of the following parts, under the general title Implants for surgery Wear of total intervertebral spinal disc prostheses: Part 1: Loading and displacement parameters for wear testing and corresp
18、onding environmental conditions for test Part 2: Nucleus replacements BS ISO 18192-2:2010INTERNATIONAL STANDARD ISO 18192-2:2010(E) ISO 2010 All rights reserved 1Implants for surgery Wear of total intervertebral spinal disc prostheses Part 2: Nucleus replacements 1 Scope This part of ISO 18192 defin
19、es a test procedure for spinal nucleus prostheses under the relative angular movement conditions specified by ISO 18192-1. This part of ISO 18192 is applicable to both lumbar and cervical prostheses. It is not applicable to total disc replacements and facet joint replacements. The method includes we
20、ar and fatigue testing. Additional mechanical tests such as creep tests can be required. This part of ISO 18192 does not reproduce the complex in vivo loads and motions. The wear and fatigue data obtained with this test method will enable comparison between different types of implant but can differ
21、from the clinical wear performance. The user of this part of ISO 18192 should consider running additional tests addressing specific safety issues of the individual implant design to be tested. 2 Normative references The following referenced documents are indispensable for the application of this doc
22、ument. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 14242-2, Implants for surgery Wear of total hip-joint prostheses Part 2: Methods of measurement ISO 18192-1, Implants for surgery
23、 Wear of total intervertebral spinal disc prostheses Part 1: Loading and displacement parameters for wear testing and corresponding environmental conditions for test 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 18192-1 and the following apply. 3.1
24、 origin centre of the coordinate system located at the geometrical centre of the simulated annulus NOTE See Figure 1. 3.2 cycle limit number of cycles at which the test is terminated if no functional failure has occurred BS ISO 18192-2:2010ISO 18192-2:2010(E) 2 ISO 2010 All rights reserved4 Principl
25、e The nucleus replacement is placed in a test station in accordance with ISO 18192-1 (see Figure 1). The shear stiffness of the annulus is simulated by a motion restraint system. The apparatus applies a specified time-varying force on the nucleus replacement, together with specified relative angular
26、 displacements. If polymers are the object of investigation, a control specimen is subjected to the same time-varying force to determine the creep of the test specimen and/or the amount of mass change due to fluid transfer. The test takes place in a controlled environment simulating physiological co
27、nditions. Key 1 ball bearing 5 origin 2 motion restraint system 6 lower endplate 3 upper endplate 7 test chamber 4 nucleus device Figure 1 Principle of the test set-up 5 Reagents and materials 5.1 Fluid test medium Calf serum diluted with de-ionized water (balance) to a concentration of 20 g 2 g pro
28、tein/l. The fluid test medium may be filtered through a 2 m filter, if desired. To minimize microbial contamination, the fluid test medium shall be stored frozen until required for test. An anti-bacterial and anti-fungal reagent (such as sodium azide) shall be added. Such reagents can be potentially
29、 hazardous. The addition of 20 mmol/l EDTA1)may be used to bind calcium in solution and to minimize precipitation of calcium phosphate on the bearing surfaces. The effect of EDTA will depend on the material combination tested. The absence of EDTA from the fluid test medium shall be justified by the
30、user. NOTE Alternative test fluids such as Hanks solution can be used. Routine monitoring of the pH of the fluid test medium should be undertaken. If it is, the values shall be included in the test report see Clause 9 item l) 6). 1) Ethylenediaminetetraacetic acid. BS ISO 18192-2:2010ISO 18192-2:201
31、0(E) ISO 2010 All rights reserved 35.2 Test and control specimens A minimum of six samples is recommended for wear/fatigue testing. At least one additional sample is recommended to correct weight gain by fluid uptake (soak control). The soak control(s) shall be loaded according to the load profile g
32、iven for the type of implant (see Table 1). The user may decide not to use a soak control when testing materials that do not absorb surrounding fluid (for example metal materials) or if weight readings are impractical due to high fluid absorption of the material to be tested (for example, hydrogels)
33、. If fewer than six samples are tested, appropriate justification shall be given. NOTE The number of specimens tested can be the subject of national legislation. 6 Apparatus 6.1 Testing machine The testing machine shall conform to ISO 18192-1. 6.2 Motion restraint system A motion restraint system ca
34、pable of applying a restraining force in the horizontal plane is used in order to simulate the shear stiffness of the annulus. The magnitude of the restraining force is proportional to the horizontal displacement of the superior side of the implant. The stiffness of the motion restraint system shall
35、 be 115 N/mm 10 N/mm (see Reference 7). An example of a motion restraint system is shown in Figure 2. Figure 2 Example (half model) of a motion restraint system using an array of springs The endplates are made of a corrosion resistant material with a roughness value of Ra = 0,05 m 0,01 m. NOTE The s
36、hape of the endplates will depend on the specimen to be tested. A concave shape of the endplates might be required to prevent luxation of the nucleus device. An elliptical shape might be helpful to prevent rotation of the nucleus device. 6.3 Means of aligning and positioning Align the test specimen
37、in the superior position, so that its instantaneous axis of rotation at the neutral position is situated at the centre of the axes of rotation of the testing machine and ensure that the same position and orientation can be reproduced following removal for measurement or cleaning, if required. BS ISO
38、 18192-2:2010ISO 18192-2:2010(E) 4 ISO 2010 All rights reserved6.4 Test chamber The test chamber should be completely sealed from the external environment. The test chamber encloses the specimen and the endplates. NOTE Generation of wear particles at the fixation of the endplates within the test cha
39、mber should be avoided although it will not always be possible to completely avoid the generation of wear particles. 6.5 Temperature control system The temperature control system shall be capable of maintaining the temperature of the fluid test medium surrounding the test specimen at (37 2) C. 7 Cyc
40、le limit The cycle limit shall be 1 107cycles unless the submitter of the specimen requests a different cycle limit, which may be used with appropriate justification. NOTE The cycle limit can be the subject of national legislation. 8 Procedure 8.1 Clean the test specimen. NOTE Cleaning of the test s
41、pecimen can be carried out as described in ISO 14242-2 or by an alternative method. 8.2 Make any initial measurements that are required to determine the subsequent amount of wear and/or creep, and to calibrate each test station using a load cell. Undertake this calibration while the load is being de
42、veloped at other stations, if any, in the test rig. Measure the wear of the test specimen by one of the methods described in ISO 14242-2. 8.3 Mount the specimen in the testing machine. 8.4 Take the control specimen and repeat steps in 8.1, 8.2 and 8.3. 8.5 Introduce the fluid test medium (see 5.1) t
43、o completely fill the test chamber. Maintain the temperature of the surrounding fluid at (37 2) C, taking the measurement at a location representative of the bulk temperature of the fluid. 8.6 Wait until the specimen has reached steady state temperature. 8.7 Start the testing machine and adjust it s
44、o that the loads given in Table 1 and displacements specified by ISO 18192-1 are applied to the test specimen. Table 1 Load parameters of the testing machine Region Load (N) max. 75 Cervical min. 25 max. 1 000 Lumbar min. 300 NOTE The loads given in this table have been reduced by 50 % compared to t
45、hose specified in ISO 18192-1 (see References 2 and 3). BS ISO 18192-2:2010ISO 18192-2:2010(E) ISO 2010 All rights reserved 58.8 Operate the testing machine at a frequency of 1 Hz with an accuracy of 0,1 Hz. Test frequencies up to 2 Hz may be used. The implications of test frequencies higher than 1
46、Hz on the implant material behaviour as well as on the accuracy of the testing machine shall be investigated by the user. Adequate justification shall be given by the user. 8.9 Replace the fluid test medium completely at least every 5 105cycles, or every seven days, whichever is shorter. 8.10 Stop t
47、he test for measurements at least at 5 105cycles, 1 106cycles and at least every 5 105cycles thereafter until the test is terminated (see 8.14). 8.11 Remove the test specimen from the testing machine and clean the test specimens. NOTE Cleaning of the test specimen can be carried out as described in
48、ISO 14242-2 or by an alternative method. 8.12 Take wear measurements. Reinstall the test specimen in the testing machine (8.3 and 8.4). 8.13 Repeat the steps given in 8.6 to 8.12 until the test is terminated (see 8.14). 8.14 Continue the test until one of the following occurs: a) completion of the c
49、ycle limit; b) functional or user defined failure of the implant. NOTE A mechanical failure might not necessitate termination of the test since this test method attempts to characterize the time dependent wear properties of the device. 9 Test report The test report shall include the following information: a) a dated reference to this part of ISO 18192, i.e. ISO 18192-2:2010; b) the identity of the test specimens, as stated by the submitter of the specimens for test, including size,
