1、BS ISO 7206-13:2016Implants for surgery Partialand total hip joint prosthesesPart 13: Determination of resistance totorque of head fixation of stemmed femoralcomponentsBSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS ISO 7206-13:2016 BRITISH STANDARDNational forewo
2、rdThis British Standard is the UK implementation of ISO 7206-13:2016.The UK participation in its preparation was entrusted toT e c h n i c a l C o m m i t t e e C H / 1 5 0 / 4 , S u r g i c a l I m p l a n t s - B o n e a n d J o i n tReplacements.A list of organizations represented on this committ
3、ee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2016.Published by BSI Standards Limited 2016ISBN 978 0 580 87687 5ICS 11.040.40Com
4、pliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 31 July 2016.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dBS ISO 7206-13:2016 ISO 2016Imp
5、lants for surgery Partial and total hip joint prostheses Part 13: Determination of resistance to torque of head fixation of stemmed femoral componentsImplants chirurgicaux Prothses partielles et totales de larticulation de la hanche Partie 13: Dtermination de la rsistance au couple de la fixation de
6、s ttes des tiges fmoralesINTERNATIONAL STANDARDISO7206-13First edition2016-07-01Reference numberISO 7206-13:2016(E)BS ISO 7206-13:2016ISO 7206-13:2016(E)ii ISO 2016 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2016, Published in SwitzerlandAll rights reserved. Unless otherwise specified, no p
7、art 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 can be requested from either ISO at the address below or ISOs member
8、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 7206-13:2016ISO 7206-13:2016(E)Foreword ivIntroduction v1 Scope . 12 Normative references 13 Terms and def
9、initions . 14 Principle 15 Apparatus . 16 Procedure. 26.1 Test specimen and sample size . 26.2 Assembly of test specimen (installation) . 26.3 Head fixation . 26.4 Torque of head fixation 36.5 Performance criteria 36.6 Test report . 37 Disposal of test specimens . 4Bibliography 6 ISO 2016 All rights
10、 reserved iiiContents PageBS ISO 7206-13:2016ISO 7206-13:2016(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical com
11、mittees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
12、 International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedures used to develop 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 th
13、e different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/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. I
14、SO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the 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 doc
15、ument is information given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trad
16、e (TBT) see the following URL: Foreword - Supplementary informationThe committee responsible for this document is ISO/TC 150, Implants for surgery, Subcommittee SC 4, Bone and joint replacements.ISO 7206 consists of the following parts, under the general title Implants for surgery Partial and total
17、hip joint prostheses: Part 1: Classification and designation of dimensions Part 2: Articulating surfaces made of metallic, ceramic and plastics materials Part 4: Determination of endurance properties of stemmed femoral components Part 6: Endurance properties testing and performance requirements of n
18、eck region of stemmed femoral components Part 10: Determination of resistance to static load of modular femoral heads Part 12: Deformation test method for acetabular shells Part 13: Determination of resistance to torque of head fixation of stemmed femoral componentsiv ISO 2016 All rights reservedBS
19、ISO 7206-13:2016ISO 7206-13:2016(E)IntroductionSome designs of stemmed femoral components of total hip joint prostheses comprise a stem/neck component and a bearing head component, which is commonly in the form of a partial sphere incorporating a female fixation feature for attachment to the neck of
20、 the stem. Such heads are generally produced using metal or ceramic material. It is important that after assembly, whether by the manufacturer or by the surgeon in the operating theatre, the head subsequently remains immobile on the neck, because movement of a metal or a ceramic femoral head compone
21、nt on a metal stem/neck component will cause the metal components to wear, while metal-on-metal movement may lead to severe fretting corrosion (see Reference 1).It is essential, therefore, that the strength of the fixation between the head and the neck is sufficient to withstand the torque likely to
22、 be transmitted through the prosthesis in use. The maximum torque applied to the interface connection depends on several design, material, and manufacturing specific parameters, e.g. pairing of bearing materials, bearing diameter, and clearance, surface finish, etc. (see Reference 2).The locking str
23、ength of the interface connection depends on several design, material, and manufacturing specific parameters for the taper geometry of the mating components, as taper angle and tolerances, taper clearance, surface finish, etc. In consequence, the torsional locking strength of nominal identical taper
24、 fixations might vary significantly (see Reference 3) and needs to be determined prior to clinical use.Clinical failure of taper connections is related to particle generation by interface micromotion, fretting, and fatigue failure (see Reference 4). Torsional interface stability is essential for sta
25、ble fixation of taper connections in order to limit the above listed adverse effects. ISO 2016 All rights reserved vBS ISO 7206-13:2016BS ISO 7206-13:2016Implants for surgery Partial and total hip joint prostheses Part 13: Determination of resistance to torque of head fixation of stemmed femoral com
26、ponents1 ScopeThis part of ISO 7206 describes a method of determining the torque required, under specified laboratory conditions, to loosen the fixation of the head of hip joint prostheses in which the head is not intended to rotate relative to the neck. It applies to the femoral component of total
27、or partial hip joint replacements in which the head and neck/stem (in the following referred to as cone) are secured together by a locking conical taper or any other means and in which the head and cone are separate components, and which are made of metallic or non-metallic materials.This part of IS
28、O 7206 does not cover methods of examining the test specimens; these should be agreed between the test laboratory and the party submitting the specimen for test.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for i
29、ts application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 7206-1, Implants for surgery Partial and total hip joint prostheses Part 1: Classification and designation of dimensionsI
30、SO 7206-10, Implants for surgery Partial and total hip-joint prostheses Part 10: Determination of resistance to static load of modular femoral headsISO 7500-1, Metallic materials Verification of static uniaxial testing machines Part 1: Tension/ compression testing machines Verification and calibrati
31、on of the force-measuring system3 Terms and definitionsFor the purposes of this document, the terms and definitions given in ISO 7206-1 and ISO 7206-10 apply.4 PrincipleA static torque is applied to the head/cone assembly of the hip-joint prosthesis and increased until the connection between the hea
32、d and the cone fails or until the chosen maximum torque has been applied without occurrence of failure.5 Apparatus5.1 Testing machine, according to ISO 7500-1 requirements, shall have the following characteristics: ability to apply an axial compressive force through the axis of the head/cone for ass
33、embly, with an accuracy of 1 % of full scale reading;INTERNATIONAL STANDARD ISO 7206-13:2016(E) ISO 2016 All rights reserved 1BS ISO 7206-13:2016ISO 7206-13:2016(E) ability to apply an axial force to a certain point of a lever arm mounted onto the cone unit or capable of directly applying a torque t
34、o the cone unit without needing a lever arm, with an accuracy of 1 % of full scale reading; instrumentation to register the values of the applied loads and the angular displacements of the test specimen to a tolerance of 0,5.5.2 Cone unit, comprises a cone of the type to which the head is to be moun
35、ted in service or a replica having the same dimensions and being made of the same material, by the same manufacturing process and to the same specification.5.3 Loading fixtures, shall be capable of sustaining expected loads and designed so that the line of action of the external torque is collinear
36、to the centre line of the head/cone assembly as indicated in Figure 2.6 Procedure6.1 Test specimen and sample sizeTo determine the torque required to loosen the fixation of a head of hip joint prostheses, a minimum of five test specimens shall be tested for each cone unit to which the head is to be
37、mounted. Each test specimen shall consist of a head and a neck of the intended fixation of the head of hip joint prostheses. Test specimens may consist of real implants or coupon components.6.2 Assembly of test specimen (installation)Assembly of ball head and cone unit is done according to ISO 7206-
38、10.6.3 Head fixation6.3.1 Preparation of the head by flattening it in the equatorial region resulting in two parallel and plane surfaces with nearly the same perpendicular distance to the ball head centre as indicated in Figure 1.The two surfaces represent an engagement for a kind of flat wrench fix
39、ation of the ball head against axial torque loading. The perpendicular distance of the parallel surfaces should be in a range of 30 % to 70 % of the ball head mean diameter. Its remaining wall thickness at the flat surfaces should be at least 2,0 mm.NOTE For a 28 mm ball head, a perpendicular distan
40、ce of 19,0 mm 0,5 mm has been found to be suitable.6.3.2 Alternatively, preparation of the head by gluing it into a spherical calotte of a metal fixture so that the calotte covers at least 140 of the heads hemisphere.The breakaway torque of the bonding should exceed the expected breakaway torque of
41、the head/cone assembly. If the bonding interface breaks before expected rotation of the head, this fact has to be recorded in the test report. An additional sample shall be tested.NOTE Epoxy resin glues have been found to be suitable for gluing the head into the fixture.6.3.3 Alternatively, preparat
42、ion of the head by embedding it into an embedding fixture using a cast resin.2 ISO 2016 All rights reservedBS ISO 7206-13:2016ISO 7206-13:2016(E)The breakaway torque of the embedding/head coupling should exceed the expected breakaway torque of the head/cone assembly. If the bonding interface breaks
43、before expected rotation of the head, this fact has to be recorded in the test report. An additional sample shall be tested.NOTE Cast resins (e.g. Technovit4071)1)have been found to be suitable for fixing the head.6.4 Torque of head fixation6.4.1 Mount the head/cone assembly into the fixture as desc
44、ribed in 6.3.Alignment of head/cone axis, head fixture axis, and the axis of the loading torque is essential for avoiding additional constraints that could bias the results. The test set-up has to provide axes alignment not only while mounting the head/cone assembly into the set-up but also while th
45、e torque load is applied until the breakaway limit is reached. Ideally, this is realized by ensuring a Degree of Freedom (DOF) of 5 for the fixed head/cone assembly, i.e. fixture blocks only rotation around head/cone axis, rotation and movements in other directions are free within a certain range (s
46、ee Figure 2).6.4.2 Apply an increasing torque to the cone unit at a loading rate of 20 Ncm/s 4 Ncm/s; or if this is not possible, at a rotation angle rate of 0,05 /s 0,01 /s continuously recording the torque/time or angle/time applied.6.4.3 Increase the load until the following occurs:a) peaking and
47、 later decrease in the recorded load profile;b) a torque limit of 50 Nm is reached which assumes that the specimen is strong enough;c) an angle limit of 20 is reached which signifies that the test should be terminated. If it could be shown that such rotation has occurred within the machine fixtures
48、or between those fixtures and the specimen (e.g. fixation glue), then that individual test shall not count towards the five specimens.6.4.4 Remove the head/cone assembly from the testing machine and fixtures and examine the test specimen regarding damages especially of the taper areas of male and fe
49、male taper.6.4.5 Report the torque resistance and the displacement angle achieved at test termination and the reason for it (see 6.4.3).6.5 Performance criteriaThe party submitting the specimen for test (customer) shall define the acceptance criteria for the test as a torque equal to or greater than that of an existing, clinically successful hip head/cone assembly. The acceptance criteria should contain both a lower limit for the mean torque and a lower torque limit for each sample tested.6.6 Test re
