1、Designation: F 1223 05Standard Test Method forDetermination of Total Knee Replacement Constraint1This standard is issued under the fixed designation F 1223; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、 A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the establishment of a databaseof total knee replacement (TKR) motion characteristics withthe intent of dev
3、eloping guidelines for the assignment ofconstraint criteria to TKR designs. (See the Rationale inAppendix X1.)1.2 This test method covers the means by which a TKRconstraint may be quantified according to motion delineated bythe inherent articular design as determined while under specificloading cond
4、itions in an in vitro environment.1.3 Tests deemed applicable to the constraint determinationare antero-posterior draw, medio-lateral shear, rotary laxity,valgus-varus rotation, and distraction, as applicable. Alsocovered is the identification of geometrical parameters of thecontacting surfaces whic
5、h would influence this motion and themeans of reporting the test results. (See Practices E4.)1.4 This test method is not a wear test.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to estab
6、lish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E4 Practices for Force Verification of Testing MachinesF 2083 Specification for Total Knee Prosthesis3. Terminology3.1 DefinitionsItems in
7、this category refer to the geo-metrical and kinematic aspects of TKR designs as they relate totheir human counterparts:3.1.1 anterior curvaturea condylar design which is gen-erally planar except for a concaveupward region anteriorlyon the tibial component.3.1.2 anterior posterior (AP)any geometrical
8、 lengthaligned with the AP orientation.3.1.3 AP displacementthe relative linear translation be-tween components in the AP direction.3.1.4 AP draw loadthe force applied to the movablecomponent with its vector aligned in the AP direction causingor intending to cause an AP displacement.3.1.5 biconcavea
9、 condylar design with pronounced APand ML condylar radii seen as a “dish” in the tibial componentor a “toroid” in the femoral component.3.1.6 bearing surfacethose regions of the componentwhich are intended to contact its counterpart for load transmis-sion.3.1.7 condylesentity designed to emulate the
10、 jointanatomy and used as a bearing surface primarily for transmis-sion of the joint reaction force with geometrical propertieswhich tend to govern the general kinematics of the TKR.3.1.8 distractionthe separation of the femoral compo-nent(s) from the tibial component(s) in the z-direction.3.1.9 fle
11、xion anglethe angulation of the femoral compo-nent (about an axis parallel to the y-axis) from the fullyextended knee position to a position in which a “local” verticalaxis on the component now points posteriorly.3.1.9.1 DiscussionFor many implants, 0 of flexion canbe defined as when the undersurfac
12、e of the tibial component isparallel to the femoral component surface that in vivo contactsthe most distal surface of the femur. This technique may not bepossible for some implants that are designed to have a posteriortilt of the tibial component. In these cases, the user shallspecify how the 0 of f
13、lexion position was defined.3.1.10 hingea mechanical physical coupling betweenfemoral and tibial components which provides a singular axisabout which flexion occurs.3.1.11 hyperextension stopa geometrical feature whicharrests further progress of flexion angles of negative value.3.1.12 internal-exter
14、nal rotationthe relative angulation ofthe moveable component about an axis parallel to the z-axis.3.1.13 joint reaction forcethe applied load whose vectoris directed parallel to the z-axis, generally considered parallelto tibial longitudinal axis.3.1.14 medio-lateral (ML)the orientation that is alig
15、nedwith the y-axis in the defined coordinate system.3.1.15 ML condylar radiusthe geometrical curvature ofthe components condyle in the frontal plane.1This test method is under the jurisdiction of ASTM Committee F04 on Medicaland Surgical Materials and Devices and is the direct responsibility of Subc
16、ommitteeF04.22 on Arthroplasty.Current edition approved Apr. 1, 2005. Published April 2005. Originallyapproved in 1989. Last previous edition approved in 2004 as F 1223 04a.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For A
17、nnual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.16 ML dimensionany geometrical length aligned withthe ML orientation.
18、3.1.17 ML displacementthe relative linear translation be-tween components in the ML direction.3.1.18 ML shear loadthe force applied to the moveablecomponent with its vector aligned in the ML direction causingor intending to cause an ML displacement.3.1.19 post-in-well featurea TKR design which tends
19、 toinfluence kinematics through the coupling of a prominenteminence with a recess or housing in a mating component.3.1.20 rotary laxity (RL)degree of relative angular mo-tion permitted of moveable component about the z-axis asgoverned by inherent geometry and load conditions.3.1.21 rotary torquethe
20、moment applied to the moveablecomponent with its vector aligned to an axis parallel to thez-axis and causing or intending to cause an internal or externalrotation.3.1.22 tibial eminencea raised geometrical feature sepa-rating the tibial condyles.3.1.23 valgus-varus constraintdegree of relative angul
21、armotion allowed between the femoral and tibial components ofpost-in-well designs (or similar designs) in the coronal plane.3.2 Definitions of Terms Specific to This Standard:3.2.1 constraintthe relative inability of a TKR to befurther displaced in a specific direction under a given set ofloading co
22、nditions as dictated by the TKRs geometricaldesign. This motion is limited, as defined in this test, to theavailable articular or bearing surfaces found on the tibialcomponent. The actual relative motion values will be providedas an indicator of this type of constraint.3.2.2 coordinate system (see F
23、ig. 1)a set of arbitrarycartesian coordinates affixed to the stationary component andaligned such that the origin is located at the intersection of they and z axes.3.2.2.1 DiscussionThe y-axis is parallel to the ML direc-tion, directed medially, and is coincident with the matedcomponents contact poi
24、nts when the knee is in the neutralposition (see 7.2). The z-axis is located midway between themated components contact points (or in the case of a singularcontact point, located at that point) and aligned in the superior-inferior direction of the distal component. A third axis, x,mutually orthogona
25、l to the two previous axes is directedposteriorly. For determination of contact points, see Annex A1and Fig. 2. The contact point shall be located to a tolerance of61 mm. In the case of multiple contact points on a condyle, anaverage location of the contact points shall be used.3.2.3 degrees of free
26、domalthough the knee joint is notedto have 6 df, or directions in which relative motion is guided(three translations:AP, ML, vertical; three angulations: flexion,internal-external rotation, valgus-varus), the coupling effectsdue to geometrical features reduce this number to five whichare the bases o
27、f this test method: AP draw, ML shear,internal-external rotation, valgus-varus rotation, and distrac-tion.3.2.4 neutral position (see 7.2)that position in which theTKR is at rest with no relative linear or angular displacementsbetween components.3.2.4.1 DiscussionThis is design-dependent and therema
28、y be a unique neutral position at each flexion angle. It maybe indicated that the femoral component, when implanted, bepositioned at some angle of hyperextension as seen when thepatients knee is fully extended; this, then becomes the neutralposition for negative flexion angle tests. The neutral posi
29、tionFIG. 1 Defined Coordinate System Examples FIG. 2 Tibial Condyle Contact Point Location ExamplesF1223052may be determined by either applying a compressive force of100 N and allowing the implant to settle or by measuring thevertical position of the movable component with respect to thestationary a
30、nd using the low point of the component as theneutral point. In those implants with a flat zone and no uniquelow point, the midpoint of the flat zone can be used as theneutral point. For those implants having a tibial componentwith a posterior tilt, the user may use other means to define theneutral
31、point, but will report on how it was found.3.2.5 set pointthat numeric quantity assigned to an inputsuch as a load.3.2.6 movable componentthat component identified eitherthrough design or test equipment attributes as providing theactual relative motion values.3.2.6.1 DiscussionDepending upon the use
32、rs fixtures andthe stationary component, it can be either the tibial or femoralcomponent.3.2.7 stationary componentthat component identified ei-ther through design or test equipment attributes as being at restduring that test to which actual relative motion values arereferenced.3.3 Symbols: Paramete
33、rs3.3.1 TAPoverall AP tibial surface dimension.3.3.2 TMLoverall ML tibial surface dimension.3.3.3 x, y, zaxes of neutral position coordinate system asdefined in Annex A1.3.3.4 DISTa “yes/no” response to distraction test at thereported angle at which distraction is most likely to occur.4. Significanc
34、e and Use4.1 This test method, when applied to available productsand proposed prototypes, will attempt to provide a database ofproduct functionality capabilities (in light of the suggested testregimens) that is hoped to aid the physician in making a moreinformed total knee replacement (TKR) selectio
35、n.4.2 A proper matching of TKR functional restorative capa-bilities and recipients (patients) needs is more likely providedfor by a rational testing protocol of the implant in an effort toreveal certain device characteristics pertinent to the selectionprocess.4.3 The TKR product designs are varied a
36、nd offer a widerange of constraint (stability). The constraint of the TKR in thein vitro condition is dependent on several geometrical andkinematic interactions among the implants components whichcan be identified and quantified. The degree of TKRs kine-matic interactions should correspond to the re
37、cipients needs asdetermined by the physician during clinical examination.5. Apparatus5.1 General:5.1.1 The stationary component should be free to move onlyin directions parallel to the z-axis and not permitted to rotateabout this axis in all but the distraction test. In the distractiontest it is ful
38、ly fixed.NOTE 1In order to test asymmetrical designs, which may be asym-metrical about the sagittal or frontal planes, it may be necessary to allowadditional degrees of freedom than those discussed in 5.1, 5.2, 5.3, and5.4. For example, the anterior ridge of the tibial bearing insert may bethicker t
39、han the posterior ridge. Also the medial and lateral surfaces maynot be identical. As a result of this implant asymmetry, condylar liftoffmay occur. For example, during a rotary test, one may need to allowvalgus/varus angulation to ensure both condyles remain in contact. If onedoes allow additional
40、degree(s) of freedom, these changes to the testmethod must be included in the report. For the internal/external rotationtest, asymmetrical designs may also require a different center of rotationthan as defined in Ssection 3 andAnnexA1. If a different center of rotationis used, it must be stated in t
41、he report section.5.1.2 The movable component shall be the displaced mem-ber when under loads specific to that test and shall beinstrumented accordingly to obtain data pertinent to that test.5.1.3 Load or torque actuators producing input vectorswhich tend to displace the movable component relative t
42、o thestationary component according to the guidelines of the spe-cific tests shall be provided with a means of gradually applyingthe load or torque to the set point of that test.5.1.4 Displacement sensing devices shall be arranged so asto measure relative motion between components in accordancewith
43、the prescribed coordinate system.5.1.5 Output graphs depicting the relationship of load anddisplacement are required (See Fig. 3.)5.1.6 The moveable component shall be mounted on afixture with near zero friction or the effect of that friction mustbe subtracted from the applied force.5.1.7 Tibial Tra
44、y AlignmentThe tibial tray shall bemounted to reflect the recommended amount of posterior slope,if any.5.1.8 The femoral component alignment shall be mountedaccording to the manufacturers specifications, such that duringflexion both femoral condyles are in contact with the tibialcondyles.5.2 Antero-
45、Posterior Draw TestThe movable componentshall be rigidly set in a fixture free to move in linear directionsparallel to the x-axis only.5.3 Medio-Lateral Shear TestThe movable componentshall be rigidly set in a fixture free to move in linear directionsparallel to the y-axis only.5.4 Rotary Laxity Tes
46、tThe movable component shall berigidly set in a fixture free to move in angular displacementsabout an axis parallel to the z-axis only.5.5 Distraction Test:5.5.1 The movable component shall be rigidly set in afixture free to move in only those directions tending to permitsuch distraction. Should dis
47、traction be possible at more thanone angle of flexion the test should be conducted at that anglewhich would most likely permit the distraction.5.5.2 The stationary component shall be rigidly set in afixture and not permitted to move in those directions allowed tothe movable component.5.6 Valgus-Varu
48、s Test:5.6.1 Install the tibial component in a fixture in which it iseither completely fixed, or free to translate linearly in amedial-lateral direction (y-direction) and anterior-posterior di-rection (x-direction).5.6.2 Install the femoral component in a fixture such that itis free to rotate in the
49、 coronal plane (yz-plane). If the tibialcomponent is fixed, then the femoral component must be freeto translate medial laterally and anterior posteriorly. TheF1223053femoral component must be free to lift off of one condyle whilethe other condyle remains in contact.6. Test Specimens6.1 TKR Specimens:6.1.1 The TKR should be the manufacturers designated“standard” or “medium” size as this is more suitable to theloading regimes encountered in the tests.6.1.2 The implant shall be procured in its original packagingas supplied to
