1、BRITISH STANDARD BS7251-7: 1990 ISO TR9325: 1989 Orthopaedic joint prostheses Part7: Guide to hip joint simulatorsBS7251-7:1990 This British Standard, having been prepared under the directionof the Health Care Standards Policy Committee, waspublished under the authorityof the Board of BSI andcomes i
2、nto effect on 31 August1990 BSI11-1999 The following BSI references relate to the work on this standard: Committee reference HCC/25 Draft for comment87/51090DC ISBN 0 580 18373 4 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Health Car
3、e Standards Policy Committee (HCC/-) to Technical Committee HCC/25, upon which the following bodies were represented: British Institute of Surgical Technologists British Medical Association British Orthopaedic Association British Steel Industry British Surgical Trades Association Department of Healt
4、h Department of Trade and Industry (National Engineering Laboratory) Royal College of Surgeons of England Scottish Office Coopted members Amendments issued since publication Amd. No. Date CommentsBS7251-7:1990 BSI 11-1999 i Contents Page Committees responsible Inside front cover National foreword ii
5、 1 Scope 1 2 Recommendations for preparation of test specimens 1 3 Recommendations for apparatus (simulators) used to effect wear 3 4 Recommendations for environment in which studies take place 4 Annex A (informative) Example of procedure for cleaning test specimens 5 Annex B (informative) Example o
6、f lubricant for wear testing 5 Annex C (informative) Bibliography 5 Publications referred to Inside back coverBS7251-7:1990 ii BSI 11-1999 National foreword This Part of BS7251 has been prepared under the direction of the Health Care Standards Policy Committee and is identical with ISO/TR9325:1989 “
7、Implants for surgery Partial and total hip joint prostheses Recommendations for simulators for evaluation of hip joint prostheses” prepared by Technical Committee150, Implants for surgery, of the International Organization for Standardization (ISO). Requirements for orthopaedic implants (then termed
8、 “surgical implants”) were first published in1962 as BS3531. In1968 a part revision of BS3531:1962 was issued as BS3531-1, which dealt with surgical implants made of all materials. In1980 the first four Parts of a multi-part version of BS3531 were published. A further nineteen Parts of BS3531 were s
9、ubsequently published. In view of the increase in the number of Parts, and with a view to facilitating the implementation of published or forthcoming ISO implant standards, the British Standard relating to implants has been restructured. Accordingly the number BS3531 is reserved for standards for im
10、plants for osteosynthesis, BS7251 covers joint prostheses, BS7252 covers metallic materials for surgical implants, BS7253 covers non-metallic materials for surgical implants and BS7254 covers orthopaedic implants, i.e.aspects common to both osteosynthesis and joint replacement. Cross-references Inte
11、rnational Standard Corresponding British Standard ISO4291:1985 BS6740:1986 Method for determining departures from roundness by measuring variations in radius (Identical) BS7252 Metallic materials for surgical implants ISO5832-1:1987 Part1:1990 Specification for wrought stainless steel (Identical) IS
12、O5832-2:1978 Part2:1990 Specification for unalloyed titanium (Identical) ISO5832-4:1978 Part4:1990 Specification for cobalt-chromium-molybdenum casting alloy (Identical) ISO6474:1981 BS7253 Non-metallic materials for surgical implants Part2:1990 Specification for ceramic materials based on alumina (
13、Identical) ISO7206-2:1987 BS7251 Orthopaedic joint prostheses Part4:1990 Specification for bearing surfaces of hip joint prostheses (Identical) ISO7206-3:1988 Part6:1990 Method for determination of endurance properties of stemmed femoral components of hip joint prostheses without application of tors
14、ion (Identical) ISO7206-4:1989 Part5:1990 Method for determination of endurance properties of stemmed femoral components of hip joint prostheses with application of torsion (Technically equivalent) ISO/TR9326:1989 Part8:1990 Guidance on laboratory evaluation of change of form of bearing surfaces of
15、hip joint prosthesesBS7251-7:1990 BSI 11-1999 iii The Technical Committee has reviewed the provisions of ISO468:1982, ISO/R1024:1969, ISO1183:1987, ISO2093/2:1987, ISO5832-3:1978, ISO5833-1:1979, ISO5834-1:1985, ISO5834-2:1985, ISO5839:1985, ISO6506:1981, ISO6507-1:1982 and ISO7206-1:1985 to which r
16、eference is made in the text, and has decided that they are acceptable for use in conjunction with this standard. A related British Standard to ISO2039/2:1987 is BS2782 “Methods of testing plastics” Part3 “Mechanical properties” Method365 C “Determination of Rockwell hardness”. A British Standard do
17、es not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an ins
18、ide front cover, pagesi to iv, pages1to6, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.iv blankBS7251-7:1990 BSI 11-1999 1 1 Scope This Tech
19、nical Report gives recommendations relating to the apparatus, specimens, test conditions and procedures for the evaluation of properties of hip joint prostheses by means of hip joint simulators. NOTEAttention is drawn to ISO/TR9326 regarding the evaluation of change of form of bearing surfaces of hi
20、p joint prostheses. 2 Recommendations for preparation of test specimens 2.1 General 2.1.1 Fabrication Specimens should be prepared in the same manner, and by the same processes that are or would be used to prepare components for clinical service, in order to produce comparable bulk material properti
21、es and surface characteristics. Attention is drawn to the requirements for aspects of fabrication given in ISO5839 and ISO7206-1. 2.1.2 Weighing When studying a hip joint prosthesis that has a large mass and a small wear rate, it may not be possible to determine accurately the change of mass of comp
22、onents using this method of assessment. If a weighing method is employed, weighing should be performed using a balance with a precision of14g. The specimen should be cleaned and dried(see2.2.4 and2.3.5) before weighing, and should be handled under dust-free conditions. At least two, and preferably u
23、p to ten, weighings should be carried out on the specimen and a mean mass calculated. Further guidance on weighing is given in ISO/TR9326. 2.1.3 Reference and control specimens It is essential that reference specimens made of polymeric material used to evaluate the wear properties of experimental co
24、unterface materials or components should all be made from the same bar or sheet of material. It is preferable that reference specimens made of metallic, ceramic or composite materials used to evaluate the wear properties of experimental counterface materials or components should all be of the same b
25、atch of components. For any individual test, it is essential that control specimens, such as those used to determine the water uptake of polymeric materials and those used for loading with no movement in order to determine the amount of creep of polymeric materials, should be made from, and orientat
26、ed in the same direction relative to, the same bar or sheet of materials as the test specimen, or, if this is not possible, be made from the same batch of moulding powder and be part of the same batch of mouldings. Consideration should be given to the preparation of sufficient numbers of control and
27、 reference specimens before the start of a test programme or, if this is not possible, to confirming that the behaviour of reference specimens of heterogeneous origin is not anomalous. Recommended reference materials are a) ultra-high molecular weight polyethylene complying with ISO5834-2; b) stainl
28、ess steel of composition D complying with ISO5832-1; c) cobalt-chromium-molybdenum alloy complying with ISO5832-4; d) titanium alloy complying with ISO5832-3. 2.2 Test and control specimens made of polymeric material 2.2.1 History A detailed fabrication history should be prepared or obtained for eac
29、h specimen and should, if possible, include such information as a) grade of material; b) batch number of the material; c) method of forming the specimen (e.g.extrusion, moulding, machining); d) details of the forming process (e.g.temperature, time, pressure); e) details of other treatments (e.g.post
30、-curing, annealing, sterilization). It is essential for replicate specimens to have been prepared from, and in the same orientation relative to, the same bar or sheet of polymeric material, or be made from the same batch of moulding powder and be part of the same batch of mouldings. Attention is dra
31、wn to ISO5834-1, ISO5834-2 and ISO5839. Polymeric components should be stored in a cool, dark, dry place, not exposed to ionizing radiation.BS7251-7:1990 2 BSI 11-1999 2.2.2 Characterization It is advisable to determine and record various characteristics of the specimen before testing commences. The
32、se may include the following. Measurements should be made in a location on the specimen that will not affect the test results. a) surface hardness of the bearing surface(seeISO2039-2); b) density of the material(seeISO/R1183); c) molecular mass distribution of the material; d) degree of crystallinit
33、y; e) characterization of the surface finish of the bearing surface (e.g.surface roughness: seeISO/R468); f) form of the bearing surface (e.g.roundness: seeISO4291); g) design of component (seeISO7206-1). With regard to e), methods that have been used include profilometry, microscopy, photo-microsco
34、py, and replication techniques. Replication techniques should be used with caution because the process can leave a film of replicating agent on the surface of the specimen that can cause spurious results in subsequent testing. Care should be exercised in the selection of reagents that are allowed to
35、 contact the surface of the specimen, as any resulting chemical action can also affect test results. No attempt should be made to improve or alter the surface finish of the specimen by polishing it with abrasives, because particles of abrasive can become embedded in the polymeric material and thereb
36、y affect the surface properties. Attention is drawn toISO7206-2. 2.2.3 Sterilization The specimen should be sterilized before testing commences in order to take account of any changes in characteristics caused by the sterilizing process. A number of methods of sterilization (e.g.gamma-ray irradiatio
37、n, exposure to ethylene oxide, autoclaving) are in current use, and the specimen, if not supplied in the sterile condition, should be sterilized by the same process and under the same conditions that are, or would be, used for a component for clinical service. Replicate specimens should all be steri
38、lized in the same sterilizing equipment at the same time. 2.2.4 Cleaning Prior to (and during) testing in a simulator, thorough and careful cleaning of the specimen is essential in order to remove particulate matter and other contaminants that could affect the test result. The cleaning procedure sho
39、uld, in its principal elements, resemble that which is, or would be, used for a component for clinical service. The specimen should not be re-machined, as this would affect the properties. An example of a cleaning procedure is given in Annex A. 2.3 Test and control specimens made of metallic, cerami
40、c or composite materials 2.3.1 History A detailed fabrication history should be prepared or obtained for each specimen and should, if possible, include such information as a) composition and grade of material; b) batch number of the material; c) method of forming the specimen (e.g.forging, casting,
41、sintering); d) details of the forming process (e.g.temperature, pressure); e) details of other treatments (e.g.annealing, machining). Components containing polymeric materials should be stored in a cool, dark, dry place, not exposed to ionizing radiation. 2.3.2 Characterization It is advisable to de
42、termine and record various characteristics of the specimen before testing commences. These may include the following. Measurements should be made in a location or the specimen that will not affect the test results. a) surface hardness of the bearing surface(seeISO/R1024, ISO6506, ISO6507-1); b) the
43、grain structure of the material; c) characterization of the surface finish of the bearing surface (e.g.surface roughness: seeISO/R468); d) form of the bearing surface (e.g.roundness: seeISO4291); e) design of the component(seeISO7206-1). Regarding ceramic materials, attention is drawn toISO6474.BS72
44、51-7:1990 BSI 11-1999 3 2.3.3 Surface finish Surface finish should be typical of that achieved, or expected to be achieved, for a component for clinical service. Attention is drawn to the values for roundness and surface finish given in ISO7206-2. 2.3.4 Sterilization The recommendations given in2.2.
45、3 apply. 2.3.5 Cleaning Prior to testing, thorough and careful cleaning of the specimen is essential in order to remove particulate matter and other contaminants that could affect the properties being determined. The cleaning procedure should leave the specimen free of particles, oil, grease, and ch
46、emical residues. Passivation should have been carried out where applicable. 3 Recommendations for apparatus (simulators) used to effect wear 3.1 Test chambers The chamber in which the prosthesis is mounted forwear testing should be made entirely of corrosion-resistant material such as polymethylmeth
47、acrylate(seeISO5833-1), titanium or titanium alloy(seeISO5832-2 and ISO5832-3), and should be easily removable from the simulator in order to facilitate cleaning. The chamber should be designed so that the bearing surfaces of the test specimens are immersed in lubricant. If a machine is designed to
48、test more than one specimen simultaneously, the individual chambers should be isolated from one another to prevent contamination of one test specimen with debris from another. Considerable care should be exercised to ensure that conditions in each chamber are as near identical as possible. 3.2 Fixin
49、g of test specimen The method of fixing the specimen in the test chamber should not affect the surface finish or geometry of the specimen and should not interfere with the method selected for the measurement of wear. An example of a suitable method of fixing is the use of a replica of the outer surfaces of the test specimen, which is split into two portions to allow the specimen to be fitted in the replica. The replica, containing the specimen, may be then firmly mounted in the test chamber, taking care that the specimen does not become distorted. It is essential that the r
