1、BS ISO 7206-13:2016 Implants for surgery Partial and total hip joint prostheses Part 13: Determination of resistance to torque of head fixation of stemmed femoral components BSI Standards Publication WB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS ISO 7206-13:2016 BRITISH STANDARD Nationa
2、l foreword This British Standard is the UK implementation of ISO 7206-13:2016. The UK participation in its preparation was entrusted to T 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 t Replacements. A list of organizations represented on
3、 this committee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2016. Published by BSI Standards Limited 2016 ISBN 978 0 580 8768
4、7 5 ICS 11.040.40 Compliance with a British Standard cannot confer immunity from legal obligations. This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 July 2016. Amendments/corrigenda issued since publication Date T e x t a f f e c t e dBS IS
5、O 7206-13:2016 ISO 2016 Implants for surgery Partial and total hip joint prostheses Part 13: Determination of resistance to torque of head fixation of stemmed femoral components Implants chirurgicaux Prothses partielles et totales de larticulation de la hanche Partie 13: Dtermination de la rsistance
6、 au couple de la fixation des ttes des tiges fmorales INTERNATIONAL STANDARD ISO 7206-13 First edition 2016-0 7-01 Reference number ISO 7206-13:2016(E)BS ISO 7206-13:2016ISO 7206-13:2016(E)ii ISO 2016 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2016, Published in Switzerland All rights rese
7、rved. 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 can be requested from either IS
8、O at the address below or ISOs member body in the country of the requester. ISO copyright office Ch. de Blandonnet 8 CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 copyrightiso.org www.iso.orgBS ISO 7206-13:2016ISO 7206-13:2016(E)Foreword iv Introduction v 1 S
9、cope . 1 2 Normative references 1 3 Terms and definitions . 1 4 Principle 1 5 Apparatus . 1 6 Procedure. 2 6.1 Test specimen and sample size . 2 6.2 Assembly of test specimen (installation) . 2 6.3 Head fixation . 2 6.4 Torque of head fixation 3 6.5 Performance criteria 3 6.6 Test report . 3 7 Dispo
10、sal of test specimens . 4 Bibliography 6 ISO 2016 All rights reserved iii Contents PageBS ISO 7206-13:2016ISO 7206-13:2016(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing Internatio
11、nal 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. International organizations, governmental and non-governmental, in liaison with ISO
12、, 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 develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Par
13、t 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/IEC Directives, Part 2 (see www.iso.org/directives). Attention is drawn to the possibility that some of the
14、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 the development of the document will be in the Introduction and/or on the ISO list of patent declarations rec
15、eived (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 meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs
16、adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information The 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 par
17、ts, under the general title Implants for surgery Partial and total 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 Par
18、t 6: Endurance properties testing and performance requirements of neck 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 fixat
19、ion of stemmed femoral componentsiv ISO 2016 All rights reservedBS ISO 7206-13:2016ISO 7206-13:2016(E) Introduction Some 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
20、incorporating a female fixation feature for attachment to the neck of 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 th
21、e neck, because movement of a metal or a ceramic femoral head component 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
22、 the head and the neck is sufficient to withstand the torque likely to 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,
23、 and clearance, surface finish, etc. (see Reference 2). The locking strength 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
24、 consequence, the torsional locking strength of nominal identical taper 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 failu
25、re (see Reference 4). Torsional interface stability is essential for stable 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: Deter
26、mination of resistance to torque of head fixation of stemmed femoral components 1 Scope This 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
27、rotate relative to the neck. It applies to the femoral component of total 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
28、, and which are made of metallic or non-metallic materials. This part of ISO 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 references The following documents, in whole or in
29、part, are normatively referenced in this document and are indispensable for its 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 to
30、tal hip joint prostheses Part 1: Classification and designation of dimensions ISO 7206-10, Implants for surgery Partial and total hip-joint prostheses Part 10: Determination of resistance to static load of modular femoral heads ISO 7500-1, Metallic materials Verification of static uniaxial testing m
31、achines Part 1: Tension/ compression testing machines Verification and calibration of the force-measuring system 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 7206-1 and ISO 7206-10 apply. 4 Principle A static torque is applied to the head/cone ass
32、embly of the hip-joint prosthesis and increased until the connection between the head and the cone fails or until the chosen maximum torque has been applied without occurrence of failure. 5 Apparatus 5.1 Testing machine, according to ISO 7500-1 requirements, shall have the following characteristics:
33、 ability to apply an axial compressive force through the axis of the head/cone for assembly, with an accuracy of 1 % of full scale reading; INTERNATIONAL ST ANDARD 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 po
34、int of a lever arm mounted onto the cone unit or capable of directly applying a torque to 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 tole
35、rance of 0,5. 5.2 Cone unit, comprises a cone of the type to which the head is to be mounted 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 e
36、xpected loads and designed so that the line of action of the external torque is collinear to the centre line of the head/cone assembly as indicated in Figure 2. 6 Procedure 6.1 Test specimen and sample size To determine the torque required to loosen the fixation of a head of hip joint prostheses, a
37、minimum of five test specimens shall be tested for each cone unit to which the head is to be 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
38、test specimen (installation) Assembly of ball head and cone unit is done according to ISO 7206-10. 6.3 Head fixation 6.3.1 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 centr
39、e as indicated in Figure 1. The two surfaces represent an engagement for a kind of flat wrench fixation 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
40、 at the flat surfaces should be at least 2,0 mm. NOTE For a 28 mm ball head, a perpendicular distance 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
41、heads hemisphere. The breakaway torque of the bonding should exceed the expected breakaway torque of 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 g
42、lues have been found to be suitable for gluing the head into the fixture. 6.3.3 Alternatively, preparation 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
43、 should exceed the expected breakaway torque of 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 Cast resins (e.g. Technovit 4071) 1)have been found to be suitable
44、 for fixing the head. 6.4 Torque of head fixation 6.4.1 Mount the head/cone assembly into the fixture as described 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
45、has to provide axes alignment not only while mounting the head/cone assembly into the set-up but also while the 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
46、 rotation around head/cone axis, rotation and movements in other directions are free within a certain range (see 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 re
47、cording the torque/time or angle/time applied. 6.4.3 Increase the load until the following occurs: a) peaking and 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 th
48、at the test should be terminated. If it could be shown that such rotation has occurred within the machine fixtures 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 testi
49、ng machine and fixtures and examine the test specimen regarding damages especially of the taper areas of male and female 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 criteria The 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. T
