1、Designation: F3129 16Standard Guide forCharacterization of Material Loss from Conical TaperJunctions in Total Joint Prostheses1This standard is issued under the fixed designation F3129; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide specifies a method to measure the surfaceand estimate the in-vivo material loss from the con
3、ical taperjunctions, such as the femoral head/stem junction or adaptersleeve from explanted modular hip prosthesis, modular knee orshoulder joints. This guide is applicable to any articulatingbearing material, stem material and conical taper size. Theprinciples in this guide may be applied to other
4、designs of taperjunction, such as the modular stem/neck junction found insome hip joints.1.2 This guide covers the measurement of the surface andestimation of depth of material loss and volume of material lossand taper geometry using a Roundness Machine (1-4), Coor-dinate Measuring Machine (CMM) (5)
5、 and Optical CoordinateMeasuring Machine (6, 7).2Other measurement equipmentmay be used to measure the surface if the resolution andaccuracy of the measurements are comparable with the instru-ments detailed in this standard. The measurement and analysisprotocols should be based on those described in
6、 this standard.NOTE 1The maximum depth of material loss is sensitive to thenumber and spacing of data points.1.3 The measurement techniques in this standard guide usemeasurements taken on the surface of the taper using stylusinstruments. The material loss/corrosion mechanisms in thetaper junction ma
7、y lead to oxide layers or corrosion productsdeposited on the surface of the taper. These layers may lead toan underestimation of the volume of material loss.1.4 The explants may have debris or biological deposits onthe surfaces of the taper junctions. These deposits will preventthe measurement of th
8、e actual surface of the taper junction andtheir effect on the measurement must be considered whendeciding the cleaning protocol. Normally, the taper surfaceswill be cleaned before measurements are taken.1.5 This standard may involve hazardous materials, opera-tions and equipment. As a precautionary
9、measure, explanteddevices should be sterilized or minimally disinfected by anappropriate means that does not adversely affect the implant orthe associated tissue that may be the subject of subsequentanalysis. A detailed discussion of precautions to be used inhandling human tissues can be found in IS
10、O 12891-1. Thisstandard does not purport to address all of the safety concerns,if any, associated with its use. It is the responsibility of the userof this standard to establish appropriate safety and healthpractices and determine the applicability of regulatory limita-tions prior to use.2. Referenc
11、ed Documents2.1 ASTM Standards:3F561 Practice for Retrieval and Analysis of MedicalDevices, and Associated Tissues and Fluids2.2 ISO Standards:4ISO 12181-1-2003 Geometrical Product Specifications(GPS)Roundness Part 1: Vocabulary and Parameters ofRoundnessISO 12181-2-2003 Geometrical Product Specific
12、ations(GPS)Roundness Part 2: Specification OperatorsISO 4287:1997 Geometrical Product Specifications (GPS)Surface Texture: Profile MethodTerms, Definitions andSurface Texture ParametersISO 4287:1997/Cor 1:1998 Geometrical Product Specifica-tions (GPS)Surface Texture: Profile MethodSurfaceand its Par
13、ametersISO 4287:1997/Cor 2:2005 Geometrical Product Specifica-tions (GPS)Surface Texture: Profile MethodMeasurement of Surface Roughness ParametersISO 25178-2 Geometric Product Specifications (GPS)Surface Texture: ArealPart 2: Terms, Definitions andSurface Texture Parameters1This guide is under the
14、jurisdiction of ASTM Committee F04 on Medical andSurgical Materials and Devices and is the direct responsibility of SubcommitteeF04.22 on Arthroplasty.Current edition approved April 15, 2016. Published May 2016. DOI: 10.1520/F312916.2The boldface numbers in parentheses refer to the list of reference
15、s at the end ofthis standard.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4Available from American Nationa
16、l Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13. Terminology3.1 Definitions:3.1.1 For the purposes of this standard the following defi-ni
17、tions shall apply.3.1.2 form deviations, ndeviations from the nominal de-signed shape of the conical taper implants that are not the resultof material loss. Form deviations may result from manufactur-ing tolerances, or due to deformation during implantation orrevision procedures.3.1.3 iatrogenic dam
18、age, ndamage induced inadvertentlyby surgeon during explantion of components.3.1.4 material loss, ndeviations from the as-manufacturedshape due to loss of material from the conical taper surfaces.3.1.5 maximum depth of material loss, nthe maximumpenetration normal to the taper surface due to in-vivo
19、 materialloss mechanisms. The maximum depth of material loss wouldnormally occur in a highly localized area, which may besignificantly deeper than the surrounding area. The estimationof maximum depth of material loss is highly sensitive to thenumber and pattern of data point measured. There may be l
20、ittlecorrelation between the maximum depth of material loss andthe volume of material loss from the surface.3.1.6 volumetric material loss, nthe volume of materialremoved from the taper surface as a result of in-vivo materialloss mechanisms.4. Analysis Preparation4.1 All components shall be cleaned
21、in accordance with theprocedure detailed in ASTM F561.NOTE 2Surface deposits of wear, corrosion or biological products onthe surface of the as-manufactured regions will affect the accuracy of theestimated surface unless removed or excluded from the analysis.4.2 The temperature of the analysis labora
22、tory shall bemaintained at 20C 6 2C. The components shall be main-tained at the temperature of the analysis laboratory for at least24 hours before the measurement to ensure dimensionalstability.4.3 Apparatus3D Coordinate measuring machine or aCNC controlled Roundness Machine with automated centering
23、and leveling procedure.4.4 In order to measure axial profiles in the taper, theroundness machine must have the capability to measure“vertical straightness” profiles and “arcuate correction” tocompensate for the arcuate motion of the stylus.4.5 StylusThe stylus acts as a morphological filter, me-chan
24、ically filtering short wavelength roughness features fromthe measured surface profile. The use of a diamond stylusallows surface roughness to be simultaneously measured withform (with sufficient spacing of data points) (8).4.6 The stylus choice may introduce errors into the esti-mated material loss.
25、 The “imprinting of microgrooves fromthe stem cone taper onto the head bore taper has been reportedin the literature. This may lead to a “saw tooth” topography inthe regions of material loss with an amplitude of tens ofmicrons. If a ball stylus (rather than a diamond stylus used forsurface topograph
26、y measurements) is used, the stylus will notcontact the bottom of the valleys which will lead to the volumeof material loss being under estimated (Fig. 1). Furthermore,measurements with a point spacing of hundreds of microns willnot resolve the surface topography and lead to an underesti-mation of t
27、he volume of material loss.4.7 Generally, the location of material loss in explantedhead bore taper will fall into two patterns; Type 1 (Fig. 2) andType 2 (Fig. 3). In Type 1 pattern of material loss, the stemcone taper contacts the head bore taper in the center, whichleaves as-manufactured surface
28、at each end of the taper and theregion material loss in the center. In Type 2 pattern of materialloss, the stem cone taper contacts the head bore taper at oneend of the head bore taper, which leaves as-manufacturedsurface at only one end of the taper and the region of materialloss at the other. All
29、other patterns of material loss can beclassified as Type 3.NOTE 3Head bore tapers may not be a continuous cone to the bottomof the taper.FIG. 1 Schematic Diagram Showing Ball Stylus Acting as a Morphological Filter Which May Lead to an Underestimation of the MaterialLoss from Taper JunctionsF3129 16
30、24.8 Bishop et al (5) described “asymmetric” and “axisym-metric” patterns of material loss in explanted heads. Thesepatterns of material loss may be sub divisions of Type 1 andType 2 material loss.4.9 Generally, either the whole (Type 1) or most (Type 2) ofthe stem cone taper surface will have been
31、in contact with thehead bore taper taper. This may mean that there is noas-manufactured surface remaining to allow the as-manufactured shape to be estimated. However, it has beenreported that explanted stems have “relatively little” materialloss (5, 9) . Examination of the surface topography of the
32、stemmay allow identification of as-manufactured regions and re-gions of material loss.4.10 Orthopaedic tapers are not normally intended to haveline-to-line contact. Due to design intent or manufacturingtolerances, there is often an angular mismatch between thestem cone taper and head bore taper. Thi
33、s has been describedas the taper angle clearance, which is defined as the differencebetween the head taper angle and stem taper angle (10). Thetaper angle is defined as twice the measured half angle of thegeometric cone forming the taper. See Fig. 4.5. Calibration of Roundness Machine and Alignment
34、ofComponents5.1 Calibrate the out of roundness machine according tomanufacturers instructions. When measuring tapers using thevertical axis of a roundness machine, the angle of the stylusrelative to the gauge will change as the diameter of the taperchanges. As the stylus pivots the effective beam le
35、ngth of thestylus is shortened giving rise to arcuate errors. These errorsshould be taken account of by using a set of calibrationconstants in the software that compensate for arcuate errors andother non-linearity errors. See Fig. 55.2 Verification of taper angle, straightness and roundnessmeasureme
36、nts: Use the measurement strategies in this standardto measure the angle, straightness and roundness of a referencetaper gauge to verify the calibration of the roundness machine.5.3 Align the taper axis of rotational symmetry with thespindle axis of rotation of the roundness machine usingcentering a
37、nd leveling routines. Ensure that as-manufacturedregions of the taper surface are used for alignment as theregions of material loss may not be concentric to the taper axis.NOTE 4If a large proportion of the taper surface has material loss oriatrogenic damage, then a ring (head) or plug (stem) gauge
38、may be placedon top of the taper for the leveling procedure.NOTE 5The face must be perpendicular to the contact surface.5.4 Nondestructively mark the retrieved taper axiscomponent, or identify a landmark feature to provide anangular reference around the axis of rotational symmetry, sothat the measur
39、ed location of material loss can be co-registeredwith the position on the actual component. Set a height datum.NOTE 6It may not be possible to get an accurate measurement of afeature to set as height datum, especially if there is a large chamfer at theend of the taper. However, it should be possible
40、 to get an approximateheight datum by aligning the stylus by eye with the top of the taper.FIG. 2 Schematic Diagram Showing Type 1 Pattern of Material Loss from the Head Bore Taper. The stem cone taper contact is in thecenter of the head bore taper, leaving as-manufactured regions at each end of the
41、 head bore taper.FIG. 3 Schematic Diagram Showing Type 2 Pattern of Material Loss from the Head Bore Taper. The stem cone taper contact at one endof the head bore taper, leaving as-manufactured regions at only one end of the head bore taper (this may occur at the mouth or throatend of the taper).F31
42、29 1636. Calibration of Coordinate Measuring Machine andAlignment of Components6.1 Calibrate the CMM according to the manufacturersinstructions.6.2 Verification of taper angle, straightness and roundnessmeasurements: Use the measurement strategies in this standardto measure the angle, straightness a
43、nd roundness of a referencetaper gauge to verify the calibration of the roundness machine.6.3 Align the taper axis of rotational symmetry with thecoordinate system of the CMM. Ensure that as-manufacturedregions of the taper surface are used for alignment as theregions of material loss may not be con
44、centric to the taper axis.NOTE 7If a large proportion of the taper surface has material loss oriatrogenic damage, then a ring (head) or plug (stem) gauge may be placedon top of the taper to for the leveling or the top face of the stem taper andsleeve may be used as datum surfaces.6.4 Nondestructivel
45、y mark the retrieved component, oridentify a landmark feature to provide an angular referencearound the axis of rotational symmetry, so that the measuredlocation of material loss can be co-registered with the positionon the actual component. If possible set a vertical heightdatum.7. Measurement of T
46、aper Surface7.1 The surface of the taper may be measured using axialprofiles or circumferential profiles or a combination of both.The use of circumferential or axial profiles will allow indi-vidual profiles to be analyzed. For 3D measurements, othermeasurement strategies may be used.7.2 Circumferent
47、ial ProfilesMeasure a series of 360roundness profiles around the inner surface of the head boretaper inside the femoral head or the outer surface of the stemcone taper on the femoral stem as shown in Fig. 6. Themeasurements should extend as close to the base of the headtaper as possible, without cau
48、sing the stylus to contact the endof the taper.NOTE 8Some stem tapers may have a micro-grooved structure on thesurface and “imprinting” of the microgrooves onto the head surface hasbeen reported. These surfaces are highly anisotropic, and circumferentialprofiles will be almost parallel to these feat
49、ures. Generally these micro-groves are in the form of a helix and care must be taken to ensure that anycircumferential measurements are not misinterpreted; in a circumferentialprofile, the stylus may cross a microgroove.7.3 Axial ProfilesMeasure a series of vertical straightnessprofiles from the base of the taper as shown in Fig. 7. For theroundness machine, ensure that the whole measurement can beFIG. 4 Schematic Diagram of Head and Stem Taper Showing the Concept of Taper Angle ClearanceFIG. 5 Diagram Showing Change in Beam Length of Stylus Instru
