1、Implants for surgery Determination of impact resistance of ceramic femoral heads for hip joint prosthesesBS ISO 11491:2017BSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06National forewordThis British Standard is the UK implementation of ISO 11491:2017.The UK particip
2、ation in its preparation was entrusted to Technical Committee CH/150/4, Surgical Implants - Bone and Joint Replacements.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a con
3、tract. Users are responsible for its correct application. The British Standards Institution 2017 Published by BSI Standards Limited 2017ISBN 978 0 580 79548 0ICS 11.040.40Compliance with a British Standard cannot confer immunity from legal obligations. This British Standard was published under the a
4、uthority of the Standards Policy and Strategy Committee on 31 July 2017.Amendments/corrigenda issued since publicationDate Text affected BRITISH STANDARDBS ISO 11491:2017 ISO 2017Implants for surgery Determination of impact resistance of ceramic femoral heads for hip joint prosthesesImplants chirurg
5、icaux Dtermination de la rsistance limpact des ttes de fmur en cramique pour les prothses de la hancheINTERNATIONAL STANDARDISO11491First edition2017-07-01Reference numberISO 11491:2017(E)BS ISO 11491:2017ISO 11491:2017(E)ii ISO 2017 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2017, Publishe
6、d in SwitzerlandAll rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission
7、can be requested from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +41 22 749 01 11Fax +41 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 11491:2017ISO 11491:2017(E)Foreword i
8、vIntroduction v1 Scope . 12 Normative references 13 Terms and definitions . 14 Principle 25 Apparatus and equipment 25.2.1 Falling weight 45.2.2 Neck unit . 45.2.3 Holding jig 45.2.4 Load cell and the load cell data recorder 45.2.5 Mount and base . 55.4.1 Geometry and size 55.4.2 Sample size . 56 Pr
9、ocedure. 56.1 General 56.2 Test method for impact resistance (cyclic strength) 66.2.1 Setting the test specimen 66.2.2 Applying an impact 66.2.3 Load cell data sampling . 66.3 Test method for the cyclic load-release burst test 66.3.1 Setting the test specimen 66.3.2 Loading of the specimen . 66.3.3
10、Termination of the load-release cycles . 76.3.4 Examination of the specimen 77 Impact test: Calculation of an impact energy 78 Test report . 7Bibliography 9 ISO 2017 All rights reserved iiiContents PageBS ISO 11491:2017ISO 11491:2017(E)ForewordISO (the International Organization for Standardization)
11、 is a worldwide federation of national 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 repre
12、sented on that committee. International 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.The procedures used to devel
13、op this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/
14、IEC Directives, Part 2 (see www.iso.org/directives).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. Details of any patent rights identified during th
15、e development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents).Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.For an explanation on the voluntary
16、 nature of standards, the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html.This do
17、cument was prepared by Technical Committee ISO/TC 150, Implants for surgery, Subcommittee SC 4, Bones and joint replacements.iv ISO 2017 All rights reservedBS ISO 11491:2017ISO 11491:2017(E)IntroductionPartial and total hip joint prostheses are designed to transmit load and allow movement under high
18、 stress conditions. They are intended to replace anatomical structures and to provide function as closely as possible to the attributes of the normal natural joint. Some designs of femoral components of total hip joint prostheses comprise a ceramic femoral head and a metal femoral stem. It is import
19、ant, therefore, that the ceramic femoral head is of sufficient strength to withstand the static loads as well as the dynamic impact loads likely to be exerted on the prostheses during use. It has been found that the ISO 7206-10 test did not produce the same type of fracture for zirconia heads that w
20、ere similar to fractures produced clinically, while the test fractures produced on alumina heads were similar to clinical fractures. It is important, specifically in cases of a new ceramic material and/or new taper configurations, to know the behaviour after impact loading such as delayed fracture t
21、hat may not be detected by a purely static burst test. Hence, this document specifies two alternative test methods to determine the impact strength of ceramic femoral heads.The fracture mechanisms of ceramic ball heads occurring after an impact load may be either an immediate overload breakage or su
22、bcritical crack growth. Subcritical crack growth may then lead to failure at forces lower than the initial static burst load. In ceramic ball heads loaded via the interface between the metal trunnion (neck unit) and the ball head, subcritical crack growth may either be induced by impaction or by inc
23、remental load-release cycles with quasi-static forces. ISO 2017 All rights reserved vBS ISO 11491:2017This page deliberately left blankImplants for surgery Determination of impact resistance of ceramic femoral heads for hip joint prostheses1 ScopeThis document specifies two alternative test methods
24、for determining the impact resistance of ceramic femoral heads for hip joint prostheses.2 Normative referencesThe following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited ap
25、plies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 197-1, Copper and copper alloys Terms and definitions Part 1: MaterialsISO 4288 , Geometrical Product Specifications (GPS) Surface texture: Profile method Rules and procedures for the
26、assessment of surface textureISO 7206-10 , Implants for surgery Partial and total hip-joint prostheses Part 10: Determination of resistance to static load of modular femoral heads3 Terms and definitionsFor the purposes of this document, the terms and definitions given in ISO 720610 and the following
27、 apply.ISO and IEC maintain terminological databases for use in standardization at the following addresses: IEC Electropedia: available at http:/www.electropedia.org/ ISO Online browsing platform: available at http:/www.iso.org/obp 3.1impact energypotential mechanical energy of the falling/drop weig
28、ht used for applying the impact3.2cyclic impact resistancemaximum impact energy without failure of the test specimen, when consecutively increased impacts are applied3.3impact loadpeak measured force before fracture when impact energy or quasi-static load-release cycles are applied3.4impact velocity
29、falling weight velocity immediately prior to impact3.5quasi-static forceforce that changes slowly with time so that any mass inertia influence can be neglectedINTERNATIONAL STANDARD ISO 11491:2017(E) ISO 2017 All rights reserved 1BS ISO 11491:2017ISO 11491:2017(E)4 PrincipleThis document can be used
30、 for the purpose of material development, material comparison, quality assurance, implant system characterization, reliability analysis and design data generation.Impact resistance (cyclic strength) is determined by applying impacts of increasing energy to the head/taper construct and identifying th
31、e maximum energy that does not result in fracture. Alternatively, the impact load (cyclic strength) may be determined by quasi-static load-release cycles identifying the maximum load that does not result in fracture.NOTE These test methods are most appropriate for evaluating new types of ceramic bal
32、l head material in combination with metal stem tapers as well as new taper design specifications by comparing them with clinically established and proven ceramic ball head and metal stem taper systems.5 Apparatus and equipment5.1 Test machine for the impact test.The test machine shall have a stiff s
33、tructure capable of applying an impact to a test specimen by a falling/drop weight. The machine shall be firmly mounted on the ground or a heavy, rigid bench (e.g. granite or steel topped measuring table). The machine shall accommodate a weight of adjustable mass to fall onto the sample from adjusta
34、ble height to allow the application of a range of impact energies. The weight can be guided or free. Any guiding mechanism shall minimize friction. The guiding mechanism should not be in contact with the striking assembly. The test specimen composed of a head and neck unit shall be supported on a ho
35、lding block mounted on a load cell. The axis of the falling weight, the test specimen, the holding block and the load cell shall be aligned vertically (1) and laterally (1 mm). Fixturing to position the test specimen shall have low mass, but shall be stiff and strong enough to withstand repeated imp
36、acts.One example of the test machine is shown in Figure 1.2 ISO 2017 All rights reservedBS ISO 11491:2017ISO 11491:2017(E)Key1 falling weight assembly 9 neck unit2 falling weight stopper 10 specimen3 guiding rail 11 copper ring4 support column 12 holding block5 load cell 13 striking plate ( neck uni
37、t holder)6 load cell data recorder 14 housing7 mount 15 sleeve/bearing8 base H falling heightFigure 1 Example of testing machineIn order to avoid applying the impact load on the specimen/neck unit assembly in malposition, a linear bearing or low friction sleeve shall be installed at neck unit holder
38、. This structure can also prevent the specimen/neck unit assembly from unexpected movement after impact loading. The striking plate (neck unit holder) needs to have stiffness, diameter and thickness appropriate as the target of the falling weight, but should be as small as possible within that conte
39、xt. ISO 2017 All rights reserved 3BS ISO 11491:2017ISO 11491:2017(E)5.2 Test apparatus for the impact test.5.2.1 Falling weightImpact energy shall be calculated based on the mass of all components of the falling weight assembly. Measurement of mass and drop height shall allow the impact energy to be
40、 calculated with an uncertainty of 2 %.If impact energy is calculated from the potential energy of the drop weight then, periodically, the kinetic energy at impact shall be verified by measuring impact velocity. Any discrepancy between kinetic and potential energy shall be accounted for within the 2
41、 % uncertainty.In order to minimize the friction resistance between the falling weight and guiding rail, a linear bearing or low friction sleeve should be included in falling weight assembly.Principle or frequency of verification can refer to ISO 1482.5.2.2 Neck unitThe neck unit shall be made of th
42、e same material, to the same cone dimensions including shape and surface requirements and with the same manufacturing process as the commercial hip prosthesis part (stem) to be engaged with the mating conical bore of the ceramic femoral head, and shall have the shape to be fitted to a testing machin
43、e. An unused neck unit shall be used in each test. Care shall be taken that there is no foreign substances on the cone portion of the neck unit that contacts the ceramic femoral head.5.2.3 Holding jigThe holding jig is composed of a combination of a holding block and a copper ring.a) Holding blockTh
44、e holding block shall be made of steel and shall have dimensions and hardness described in ISO 720610 . The holding block shall be fixed to the base through a mount.NOTE The dimensions of the holding block are typically approximately 2 times the dimensions of the tested femoral heads in diameter and
45、 its height between 1,0 and 1,5 times the tested ball head diameter.b) Copper ringA copper ring shall have the shape to match the test specimen diameter as described in ISO 7206-10 but with the tolerance of 0,1 mm, and shall be made of refined copper, with minimum copper content of 99,85 % (mass/mas
46、s), according to ISO 197-1. In testing, an unused copper ring shall be used for each test specimen.5.2.4 Load cell and the load cell data recorder5.2.4.1 GeneralBy measuring and recording the force resulting from an applied impact, the forces experienced by the test specimen, as well as any abnormal
47、ities of the test, can be detected.5.2.4.2 Load cellThe load cell shall be an impact load cell (not static) and shall be rigidly mounted as specified by its manufacturer.4 ISO 2017 All rights reservedBS ISO 11491:2017ISO 11491:2017(E)5.2.4.3 Load cell data recorderThe load cell data recorder shall h
48、ave a sampling rate of at least 200 kHz, and shall be able to acquire the data of an impact load from the impact initiation to at least 500 ms thereafter.5.2.5 Mount and baseThe mount and the base shall be made of steel and robust to firmly hold the test setting.5.3 Test machine, apparatus and setup
49、 for the cyclic load-release burst test.All specifications for the test machine, the apparatus and the test setup shall be according to the static compression test described in ISO 7206-10 . The test needs to be performed force-controlled, hence, the test machine shall be capable to perform compressive tests under force control.5.4 Test specimens.5.4.1 Geometry and sizeEither commercial products of the ceramic femoral head, or test specimens manufactured with the same design and material, through the same proces
