1、BSI Standards PublicationBS ISO 16087:2013Implants for surgery Roentgenstereophotogrammetricanalysis for the assessmentof migration of orthopaedicimplantsBS ISO 16087:2013 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 16087:2013.The UK participation in its pr
2、eparation was entrusted toTechnical Committee CH/150/4, Surgical Implants - Bone and JointReplacements.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are re
3、sponsible for its correctapplication. The British Standards Institution 2013. Published by BSI StandardsLimited 2013ISBN 978 0 580 70767 4ICS 11.040.40Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandar
4、ds Policy and Strategy Committee on 31 October 2013.Amendments issued since publicationDate Text affectedBS ISO 16087:2013 ISO 2013Implants for surgery Roentgen stereophotogrammetric analysis for the assessment of migration of orthopaedic implantsImplants chirurgicaux Analyse strophotogrammtrique Ro
5、entgen pour lvaluation de la migration des implants orthopdiquesINTERNATIONAL STANDARDISO16087First edition2013-10-01Reference numberISO 16087:2013(E)BS ISO 16087:2013ISO 16087:2013(E)ii ISO 2013 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2013All rights reserved. Unless otherwise specified,
6、 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 ISO at the address below or ISOs me
7、mber body in the country of the requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 16087:2013ISO 16087:2013(E) ISO 2013 All rights reserved iiiContents PageForeword ivIntroduct
8、ion v1 Scope . 12 Terms and definitions . 13 Measurement . 33.1 Size of markers 33.2 Virtual markers . 33.3 Number and distribution of markers 43.4 Mean error of rigid body fitting 43.5 Condition number 43.6 Three-dimensional implant models . 44 Radiographic arrangement . 45 Calibration cages and re
9、ference plates . 46 Radiographs 56.1 General . 56.2 Double examinations . 57 Software . 58 Coordinate systems 58.1 Global coordinate system . 58.2 Implant coordinate system . 58.3 Reference rigid body 69 Migration 69.1 Translations . 69.2 Rotations 610 Maximum total point motion . 710.1 General . 71
10、0.2 Signed versus unsigned values 811 Validation . 811.1 Accuracy 811.2 Precision . 812 Practical issues . 812.1 Weight bearing 812.2 Follow-up intervals . 912.3 Radiation dose . 912.4 Exclusion of patients 913 Standardised output . 9Annex A (informative) Relevant formulae .11Bibliography .12BS ISO
11、16087:2013ISO 16087:2013(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 committees. Each member body interested
12、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 International Electrotechnical Commi
13、ssion (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 the different types of ISO documents sh
14、ould be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2. www.iso.org/directivesAttention 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 identif
15、ying 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. www.iso.org/patentsAny trade name used in this document is information given for the convenience of u
16、sers and does not constitute an endorsement.The committee responsible for this document is ISO/TC 150, Implants for surgery, Subcommittee SC 4, Bone and joint replacement.iv ISO 2013 All rights reservedBS ISO 16087:2013ISO 16087:2013(E)IntroductionSince its introduction in 1974,1roentgen stereophoto
17、grammetric analysis (RSA) has been widely used to assess migration of orthopaedic implants. It is a highly accurate method of quantifying three-dimensional migration between an implant and the bone it is fixed in. RSA is also used in other applications such as measuring migration between bone fragme
18、nts in e.g. bone fracture studies, and measuring wear of implants. These applications are not within the scope of this International Standard.Several studies have found implant migration to be predictive of long-term implant survival and, for most devices, measurement over two years might therefore
19、provide a surrogate outcome measure with relatively low numbers of subjects, e.g. less than 50 patients in each group in randomized studies.234A smaller number of subjects can be used in these studies as a consequence of the high accuracy of the measurement technique. Because of this, RSA is an impo
20、rtant technique in early clinical trials for screening new joint replacement prostheses.However, results from these early clinical trials are difficult to compare as different studies report their results in different formats. To facilitate comparison of outcome reported from different research grou
21、ps and because the results are obtained using different methodological procedures, there is a need for standardization of RSA investigations.The RSA method described in this International Standard requires the use of X-rays and exposes the patient to a greater X-ray exposure dose with its associated
22、 health risk. For this reason, it is neither the intention of this International Standard to recommend the routine use of RSA nor to add to existing regulatory requirements. Rather it is the intention that when RSA is used in a standardized manner, the results can be as useful and as widely applicab
23、le as possible. ISO 2013 All rights reserved vBS ISO 16087:2013BS ISO 16087:2013Implants for surgery Roentgen stereophotogrammetric analysis for the assessment of migration of orthopaedic implantsCAUTION The RSA method described in this International Standard requires the use of X-rays and exposes t
24、he patient to a greater X-ray exposure dose with its associated health risk. Careful consideration of the benefits and drawbacks of this method on a case by case basis is advisable.1 ScopeThis International Standard provides requirements for the clinical assessment of migration of orthopaedic implan
25、ts with roentgen stereophotogrammetric analysis (RSA).2 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.2.1absolute movementmovement of a rigid body relative to a fixed reference rigid body2.2accuracycloseness of agreement between a measured quantity
26、 value and a true quantity value of a measurand2.3biasestimate of a systematic measurement error2.4biplanar techniqueRSA technique where two X-ray cassettes/films/sensors are set at an angle to each other2.5calibration cagecalibration boxreference frame used to create a three-dimensional coordinate
27、system, with definition of position and orientation, and to determine the position of the two roentgen foci2.6condition numbercalculated number used to assess the distribution of markersNote 1 to entry: High condition numbers indicate poor marker distribution, while low condition numbers indicate ap
28、propriate marker distribution.Note 2 to entry: See Annex A, which establishes the methodology to determine the condition number associated with the marker distribution.2.7crossing line errorshortest distance between the two X-rays projecting the centre of a marker in the two RSA imagesINTERNATIONAL
29、STANDARD ISO 16087:2013(E) ISO 2013 All rights reserved 1BS ISO 16087:2013ISO 16087:2013(E)2.8double examinationstwo RSA examinations of the same patient within an interval of several minutes2.9helical axisscrew axisinstantaneous axis about which the decomposition of the motion of an object from one
30、 position to another has a translation along and a rotation about a single axis2.10markersmall diameter biocompatible metal sphere having a precise size and shape used as landmarkNote 1 to entry: Spherical tantalum markers serve as well-defined landmarks.Note 2 to entry: The diameter is commonly 1 m
31、m.2.11maximum total point motionMTPMlength of the translation vector of the marker or virtual marker in a rigid body that has the greatest migrationNote 1 to entry: It can only have positive values, and is not normally distributed.2.12mean error of rigid body fittingrigid body errormeasure indicatin
32、g the mean change of relative positions of markers (in the same object) over time compared to the initial, reference configurationNote 1 to entry: Annex A establishes the methodology to determine the mean error associated with the change of relative positions of markers.2.13migrationchange in positi
33、on and orientation of an implant relative to the host bone assessed between follow-up examinations2.14model-based RSARSA technique in which the position and orientation of an implant is assessed by matching a virtual projection of a three-dimensional model of the implant to the actual radiographic p
34、rojection of the implant2.15phantomobject that is used as a representative of an anatomical part2.16precisiondegree to which repeated measurements under unchanged conditions show the same results2.17reference plateplanar object holding markers used for calibration of RSA-examinations by linking its
35、two-dimensional coordinate system to the three-dimensional global coordinate system of previous RSA-examinations that were calibrated using a three-dimensional calibration cage2.18reference rigid bodyrigid body that defines a fixed coordinate system, the origin of which is located in that rigid body
36、s geometrical centre2 ISO 2013 All rights reservedBS ISO 16087:2013ISO 16087:2013(E)2.19rotation matrixmathematical expression of the three-dimensional rotation of a rigid body2.20RSAroentgen stereophotogrammetric analysisradiostereometryradiostereometric analysisroentgen stereophotogrammetrymeasure
37、ment technique that relies on stereo X-ray images and can be used to assess relative changes in position and orientation of two rigid bodies (e.g. an orthopaedic implant and host bone) relative to each otherNote 1 to entry: In order to reach a high level of accuracy, markers are used as landmarks in
38、 the bone and a calibration object (calibration cage or reference plate) is used to assess the position of two synchronised X-ray sources in the global coordinate system defined by the calibration cage.2.21virtual markerthree-dimensional point from visible landmarks or calculated from known geometry
39、 to determine a specific point of an implantNote 1 to entry: Virtual markers were formerly named fictive markers.2.22uniplanar techniqueRSA technique where the two X-ray cassettes/films/sensors are in the same plane3 Measurement3.1 Size of markersSpherical markers made of biocompatible (implant grad
40、e) metal and having a high radio-opacity (e.g. tantalum) shall be used to serve as landmarks. Marker diameters of 0,5 mm, 0,8 mm and 1,0 mm are generally used.3.2 Virtual markersVirtual markers indicate a specific part of the implant and facilitate comparison of migration data within and between stu
41、dies.EXAMPLE 1 Within a clinical RSA study of a specific implant, these virtual markers are valuable if one or more implant markers of a certain patient are obscured in the X-ray or have become loose.In different RSA studies, different prosthesis designs might have markers attached at different loca
42、tions. In order to compare the translation of specific points on the implants surface between different implant designs, virtual markers can be used.EXAMPLE 2 To compare the translation of a specific point, on the tip of different hip stems.A virtual marker is defined by the observer. Its position i
43、s indicated in both images of a single RSA-examination, and the three-dimensional position of the virtual marker is reconstructed according to the common approach of reconstructing the position of an actual prosthesis marker. It is advised that the crossing line error is less than 1 mm. A new rigid
44、body is formed when the position of the virtual marker is combined with the positions of at least three prosthesis markers. This enables the translation of the virtual marker to be determinable in subsequent (or previous) RSA examinations. Therefore, virtual markers are defined such that they move w
45、ith the implant and they can be used to calculate the translation of this specific point of the prosthesis based on the migration of the implant itself. ISO 2013 All rights reserved 3BS ISO 16087:2013ISO 16087:2013(E)3.3 Number and distribution of markersIn order to assess translations and rotations
46、 with all six degrees of freedom, markers shall be implanted on each rigid body under study so that they are not collinear. For each rigid body, at least three identical markers shall be visible on both radiographs at all examinations.NOTE 1 In cases where only one or two markers can be used in one
47、of the rigid bodies, only translations can be calculated.NOTE 2 It is strongly advised to insert at least six to seven bone markers as markers may be obscured by the implant.3.4 Mean error of rigid body fittingThe upper limit of acceptable mean error of rigid body fitting shall be related to the mar
48、ker configuration of the segment (defined by its condition number). The upper limit accepted shall be reported and should typically not exceed 0,35 mm.3.5 Condition numberFor studies of hip, knee and shoulder prostheses, condition numbers shall be below 120.For studies of small joints, such as in th
49、e fingers and the cervical spine, condition numbers shall preferably be below 150. For studies in which these high condition numbers are accepted, it is essential that the precision of the measurements is validated (see 11.2).3.6 Three-dimensional implant modelsModel-based RSA techniques do not require the attachment of metal markers to the implant but require an accurate 3D representation of the implant.78If the model-based techniques are to be used, they shall have been properly evaluated and the precision and bias of these measur
