1、Designation: F 2028 05Standard Test Methods forDynamic Evaluation of Glenoid Loosening orDisassociation1This standard is issued under the fixed designation F 2028; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last re
2、vision. 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 These test methods measure how much a prostheticglenoid component rocks or pivots following cyclic displace-ment of the hume
3、ral head to opposing glenoid rims (forexample, superior-inferior or anterior-posterior). Performanceis judged by the tensile displacement opposite each loaded rimafter dynamic rocking.1.2 The same setup can be used to test the locking mecha-nism of modular glenoid components, for example, for disas-
4、sociation.1.3 These test methods cover shoulder replacement designswith monolithic or modular glenoid components for cementedfixation.1.4 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are provided forinformation purposes only.1.5 This standard does
5、not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standa
6、rds:2E4 Practices for Force Verification of Testing MachinesF 1378 Specification for Shoulder ProsthesesF 1839 Specification for Rigid Polyurethane Foam for Useas a Standard Material for Testing Orthopaedic Devicesand Instruments33. Terminology3.1 Definitions:3.1.1 glenoidthe prosthetic portion that
7、 replaces the gle-noid fossa of the scapula and articulates with a prostheticreplacement of the humeral head. It may consist of one or morecomponents from one or more materials, for example, eitherall-polyethylene or a metal baseplate with a polymeric insert.3.1.2 humeral headthe prosthetic portion
8、that replaces theproximal humerus or humeral head and articulates with thenatural glenoid fossa or a prosthetic replacement.3.1.3 glenoid planesee Fig. 1. In symmetric glenoids, theplane is defined by joining the two articular edges; in planarand asymmetric glenoids, it is defined by the back surfac
9、e.3.1.4 axial load; axial translationthe force and displace-ment, respectively, perpendicular to the glenoid plane; the axialload simulates the net compressive external and muscle forces(see Fig. 1).3.1.5 shear load; shear translationthe force and displace-ment, respectively, parallel to the glenoid
10、 plane, applied, forexample, in the superior/inferior or anterior/posterior direction(see Figs. 1 and 2); the shear load simulates the net shearexternal and active and passive soft tissue forces.3.1.6 subluxation loadthe peak shear load required forsubluxation, for example, the peak resistive force
11、at the glenoidarticular rim opposing movement of the humeral head.3.1.7 subluxation translationthe distance from the gle-noid origin (see Fig. 2), parallel to the glenoid plane, to thepoint at which the subluxation load occurs.1These test methods are under the jurisdiction of ASTM Committee F04 onMe
12、dical and Surgical Materials and Devices and are the direct responsibility ofSubcommittee F04.22 on Arthroplasty.Current edition approved Aug. 1, 2005. Published August 2005. Originallyapproved in 2000. Last previous edition approved in 2002 as F 2028 02.2For referenced ASTM standards, visit the AST
13、M 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.3Withdrawn.FIG. 1 Glenoid Plane and Load Directions1Copyright ASTM International, 100 Barr Harbor Drive, P
14、O Box C700, West Conshohocken, PA 19428-2959, United States.3.1.8 superior/inferior (SI), anterior/posterior (AP)the SIaxis is the longest dimension and the AP axis the widestdimension of the glenoid (see Fig. 2).3.1.9 edge displacementsthe translation, perpendicular tothe glenoid plane, of a specif
15、ic point on the outside edge of theglenoid, when subjected to loading (see Fig. 3).GLENOID LOOSENING TEST METHOD4. Summary of Test Method4.1 The prosthetic glenoid component is fixed with bonecement into a bone substitute using the normal surgicaltechnique.4.2 The subluxation translation is determin
16、ed experimen-tally on additional components. This is accomplished, using abiaxial apparatus (see Fig. 3) by applying an axial loadperpendicular to the glenoid, then translating the humeral headparallel to the glenoid plane until encountering a peak shearload. This is performed in both directions, co
17、rresponding to thedirection of intended rocking (for example, superior-inferior,anterior-posterior, or an alternative angle).4.3 The edge displacements of the glenoid are measuredbefore cycling: a given axial load is first applied perpendicularto the glenoid, then the edge displacements are measured
18、 withthe humeral head in three positions: at the glenoid origin, andpositioned to 90 % of the subluxation translation (see X1.2), inboth directions, as defined in 4.2. (Cycling to 90 % of thesubluxation load would be acceptable, but is not practicallyfeasible as a result of the large displacements,
19、quick speeds,and deformable polyethylene.)4.4 The humeral head is cycled to 90 % of the subluxationdistance for a fixed number of cycles.4.5 The edge displacements (4.3) are either repeated follow-ing the cycling or measured continuously during the cycling.FIG. 2 Glenoid Axes and OriginFIG. 3 Biaxia
20、l Testing ApparatusF20280525. Significance and Use5.1 This test method is intended to investigate the resistanceof a glenoid component to loosening. Glenoid loosening is themost common clinical complication in total shoulder arthro-plasty (see X1.1). The method assumes that loosening occursbecause o
21、f edge loading, often called the rocking-horse phe-nomenon.5.2 This test method can be used both to detect potentialproblems and to compare design features. Factors affectingloosening performance include articular geometry, flange ge-ometry, materials, fixation design, bone quality, and surgicaltech
22、nique.6. Apparatus and Equipment6.1 The test apparatus shall be constructed such that an axialload is applied perpendicular to the glenoid plane and a shearload is applied parallel to the glenoid plane (see Fig. 1). Fig. 3shows the axial load to be horizontal and the shear load to bevertical; howeve
23、r, this arrangement may be reversed.6.2 A bone substitute representing the strength or glenoidcancellous bone (see X1.5) shall be used. If a polyurethanefoam is used, it shall conform to Specification F 1839.6.3 The glenoid and humeral head shall be enclosed in achamber with water heated to 37 6 2C
24、(98.6 6 3.6F), at leastfor the dynamic portion of the test (see X1.6). A buffer may beadded, if the tester deems this necessary.6.4 A means to measure the axial load, shear load, sheartranslation, and glenoid edge displacements is required. Ameans to measure the axial translation is desirable.6.5 Th
25、e tests win be performed on either mechanical orhydraulic load frames with adequate load capacity and shallmeet the criteria of Practices E4.7. Sampling and Test Specimens7.1 Aminimum of three samples shall be tested.At least twoadditional components should be used to determine the sub-luxation tran
26、slation. The test may be conducted along thesuperior-inferior axis, the anterior-posterior axis, or anotheraxis of interest to the user.7.2 All glenoid components shall be in the final manufac-tured condition. All plastic components shall be sterilizedaccording to the manufacturer-recommended specif
27、ications forclinical use.7.3 The humeral head shall include the identical radius orradii and material as the actual implant. Other features of thehumeral component such as the shaft may be omitted. Thesame head may be used for all tests unless the surface becomesdamaged.7.4 Glenoid and humeral compo
28、nents axe used in totalshoulder arthroplasty and should conform to the criteriaspecified in Specification F 1378.8. Procedure8.1 The following steps are common to both the subluxation(4.2) and rocking (4.3-4.5) tests:8.1.1 Secure the glenoid component in a bone substitutewith bone cement using the n
29、ormal surgical procedure andinstrumentation. Do not perform tests until the cement hasproperly cured.8.1.2 Position the path of the humeral head on the glenoidwithin 60.5 mm (sideways) of the desired path, for example,by using a dye to locate the contact point of the humeral head;a dye is unnecessar
30、y for congruent prostheses. Locate thecenter of the path (for the subluxation test, this need not beexact; for the rocking test, the peak loads at each rim duringcycling should be within 610 % of each other for symmetricaldesigns).8.1.3 Perform the static measurements (subluxation andedge displaceme
31、nts) either in air at room temperature or inwater at 37C. The cyclic testing must be performed in 37Cwater (see 6.3, X1.3, and X1.6).8.1.4 Apply a given axial load to the glenoid, for example,750 N (169 lb) 6 7.5 N (see X1.4).8.2 Determine the subluxation translation experimentally onseparate compon
32、ents (see X1.2):8.2.1 After applying the axial load, displace the humeralhead at a constant rate to a given displacement ensuring that apeak load is achieved in both directions. A rate of 50 mm/min(2 in./min) is recommended to avoid polyethylene creep.8.2.2 Yielding is expected at the recommended lo
33、ad anddoes not constitute a failure. The test shall be terminated if theinsert of a modular glenoid disassociates.8.2.3 Record the axial load, subluxation load, and sublux-ation translation.8.3 Measure the edge displacements before rocking:8.3.1 Create a foundation for measurements at both ends ofth
34、e glenoid at a similar distance from the back surface of theglenoid for all prostheses. One possibility is to insert 2-mm-diameter screws into the outside edge at each end of theglenoid prosthesis, parallel to the articular surface (to avoidexiting either into the articular surface or into the bones
35、ubstitute); flatten the screw head parallel to the glenoid plane.Alternative methods are acceptable.8.3.2 Rest a displacement measuring device, for example,an LVDT, DVRT, or dial gauge, on each foundation to measurethe displacements perpendicular to the glenoid plane. Continu-ous measurement is desi
36、rable, but measurement at the begin-ning and end of the rocking is sufficient.8.3.3 Condition the prosthesis/bone substitute system, forexample, for ten cycles at 0.25 Hz.8.3.4 Measure the edge displacements with the humeralhead located at the glenoid origin (see Fig. 2).8.3.5 Translate the humeral
37、head parallel to the glenoidplane to 90 % of the subluxation translation determined previ-ously (8.2) in one direction. Measure both edge displacements.8.3.6 Translate the humeral head to 90 % of the subluxationtranslation in the opposite direction and measure both edgedisplacements.8.3.7 Repeat the
38、 three readings at least once to ensurerepeatability.8.4 Cyclically translate the humeral head to 90 % of thesubluxation translation to cause a rocking motion of theglenoid at a given frequency (for example, 2 Hz as a result ofthe large translations, or up to a maximum of 6 Hz) to amaximum number of
39、 cycles (for example, 100 000, see X1.7).Maintain the axial load and specified displacement.F20280538.5 Terminate the test when either the maximum number ofcycles has been reached or a modular glenoid insert disasso-ciates.8.6 Repeat the glenoid edge displacement measurements(8.3) if measurements we
40、re not taken continuously.8.7 Testing may be continued to a higher number of cyclesif desired.9. Report9.1 The test report shall include the following:9.1.1 All details relevant to the particular implants testedincluding type, size, and lot number as well as the glenoidradius, humeral head radius or
41、 radii, and the prosthesismaterial.9.1.2 The axis and direction of testing, for example, central-superior-inferior.9.1.3 Subluxation TestThe subluxation load and transla-tion for each specimen, as well as the axial load and displace-ment rate. A chart plotting the load versus displacement withthe 90
42、 and 100 % subluxation loads clearly marked should beincluded.9.1.4 Rocking TestThe axial load, cyclic displacement,maximum number of cycles, testing frequency, and cause oftest termination. Testing parameters that differ from thoserecommended shall be justified.9.1.5 Displacement TestThe edge displ
43、acements beforeand following cycling, highlighting the tensile displacement onthe unloaded side following rocking (for example, the displace-ment opposite the loaded side minus the value with the head atthe glenoid origin).9.1.6 If the amplitude of the axial translation decreasessuddenly during the
44、test (indicating a tilt of the glenoid and theprobable onset of loosening), the number of cycles at whichthis occurred should be recorded.10. Precision and Bias10.1 The precision and bias of this test method has not beenestablished. Test results that could be used to establish preci-sion and bias ar
45、e solicited.11. Keywords11.1 arthroplasty; glenoid; loosening; subluxation; totalshoulder replacementMODULAR DISASSOCIATION TEST METHOD12. Summary of Test Method12.1 The prosthetic glenoid component is fixed into a bonesubstitute with bone cement using the normal surgical tech-nique.12.2 The subluxa
46、tion translation is determined experimen-tally on the intended test samples or additional components.This is accomplished, using a biaxial apparatus (see Fig. 3), byfirst applying an axial load perpendicular to the glenoid, thentranslating the humeral head parallel to the glenoid plane untilencounte
47、ring a peak shear load. This is performed in bothdirections, corresponding to the direction of intended rocking(for example, superior-inferior, anterior-posterior, or an alter-native angle).12.3 The humeral head is cycled to 90 % of the subluxationdistance for a fixed number of cycles (see X1.2). (C
48、ycling to90 % of the subluxation load would be acceptable, but is notpractically feasible because of the large displacements, quickspeeds, and deformable polyethylene.)13. Significance and Use13.1 This test method is intended to investigate the lockingmechanism of a modular glenoid. Disassociation o
49、f the insert isthe greatest issue in modular glenoid components. This testmethod can be used either to detect potential problems or tocompare design features.14. Apparatus and Equipment14.1 The test apparatus shall be constructed such that anaxial load is applied perpendicular to the glenoid plane and ashear load is applied parallel to the glenoid plane (see Fig. 1).Fig. 3 shows the axial load to be horizontal and the shear loadto be vertical; however, this arrangement may be reversed.14.2 The glenoid and humeral head shall be enclosed in achamber with water heated to
