1、Designation: F2028 14Standard Test Methods forDynamic Evaluation of Glenoid Loosening orDisassociation1This standard is issued under the fixed designation F2028; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revi
2、sion. 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 These test methods measure how much a prostheticanatomic glenoid component rocks or pivots following cyclicdisplacement of the
3、humeral head to opposing glenoid rims (forexample, superior-inferior or anterior-posterior). Motion isquantified by the tensile displacement opposite each loaded rimafter dynamic rocking. Similarly, these test methods measurehow much a prosthetic reverse glenoid component rocks orpivots following cy
4、clic articulation with a mating humeralliner. Motion is quantified by the magnitude of displacementmeasured before and after cyclic loading.1.2 The same setup can be used to test the locking mecha-nisms of modular glenoid components, for example, disasso-ciation of both anatomic and reverse shoulder
5、 components.1.3 These test methods cover shoulder replacement designswith monolithic or modular glenoid components for cementedfixation as well as reverse glenoid components for uncementedfixation.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are incl
6、uded in thisstandard.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 establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior t
7、o use.2. Referenced Documents2.1 ASTM Standards:2E4 Practices for Force Verification of Testing MachinesF1378 Specification for Shoulder ProsthesesF1839 Specification for Rigid Polyurethane Foam for Use asa Standard Material for Testing Orthopaedic Devices andInstruments3. Terminology3.1 Definitions
8、:3.1.1 anatomic total shoulder arthroplasty, nshoulder im-plant that has a concave glenoid component and a convexhumeral component design.3.1.1.1 anatomic glenoid, nthe concave prosthetic portionthat replaces the glenoid fossa of the scapula and articulateswith a convex prosthetic replacement of the
9、 humeral head inanatomic total shoulder arthroplasty applications. It may con-sist of one or more components from one or more materials, forexample, either all-polyethylene or a metal baseplate with apolymeric insert.3.1.1.2 humeral head, nthe convex prosthetic portion thatreplaces the proximal hume
10、rus or humeral head and articulateswith the natural glenoid fossa or an anatomic prostheticreplacement.3.1.2 reverse total shoulder arthroplasty, nshoulder im-plants that have a convex glenoid component and a concavehumeral component design.3.1.2.1 glenoid baseplate, nthe nonarticular portion of the
11、reverse glenoid component that modularly connects to theglenosphere and is usually fixed to the glenoid fossa of thescapula using bone screws without the use of cement.3.1.2.2 glenosphere, nthe convex prosthetic articular por-tion of the reverse glenoid component that articulates with theconcave pro
12、sthetic replacement of the proximal humerus orhumeral head (for example, the humeral liner).3.1.2.3 glenosphere thickness, nthe height of the truncatedsection of the sphere which composes the glenosphere. Notethat the difference between the glenosphere articular radius andthickness defines the media
13、l/lateral position of the glenoidcenter of rotation (see Fig. 1). The glenosphere thickness couldalso be affected by the geometric relation between the gleno-sphere and the glenoid baseplate.3.1.2.4 humeral liner, nthe concave prosthetic portion ofthe reverse humeral component that replaces the prox
14、imal1These test methods are under the jurisdiction of ASTM Committee F04 onMedical and Surgical Materials and Devices and are the direct responsibility ofSubcommittee F04.22 on Arthroplasty.Current edition approved March 1, 2014. Published July 2014. Originallyapproved in 2000. Last previous edition
15、 approved in 2012 as F2028 08(2012)1.DOI: 10.1520/F2028-14.2For 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.Co
16、pyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1humerus or humeral head and articulates with the convexprosthetic replacement of the glenoid (for example, the gleno-sphere).3.1.2.5 reverse glenoid, nthe convex prosthetic portionthat rep
17、laces the glenoid fossa of the scapula and articulateswith a concave prosthetic replacement of the humeral head inreverse total shoulder arthroplasty applications. The reverseglenoid may consist of one or more components from one ormore materials; most commonly, the reverse glenoid is com-posed of a
18、 metal glenosphere that is modularly connected to ametal glenoid baseplate which is fixed to the glenoid fossa.3.1.3 anterior/posterior (AP), nthe AP axis is the widestdimension of the glenoid component (see Fig. 2 and Fig. 3).3.1.4 axial load; axial translation, nthe force anddisplacement, respecti
19、vely, perpendicular to the glenoid plane.The axial load simulates the net compressive external andactive and passive soft tissue forces (see Fig. 4).3.1.5 edge displacements, nthe translation, perpendicularto the glenoid plane, of a specific point on the outside edge ofthe glenoid, when subjected to
20、 loading (see Fig. 5, Fig. 6 andFig. 7).3.1.6 glenoid plane (see X1.9),nin symmetrical anatomicglenoids, the glenoid plane is defined by joining the twoarticular edges; in planar and asymmetric anatomic glenoids, itis defined by the back (medial) surface. For a reverse shoulderit is defined as the p
21、lane created by the face of the glenoidbaseplate (see Fig. 4).3.1.7 runout, na predetermined number of cycles at whichthe testing on a particular specimen will be stopped, and nofurther testing on that specimen will be performed.3.1.8 shear load; shear translation, nthe force anddisplacement, respec
22、tively, parallel to the glenoid plane,applied, for example, in the superior/inferior or anterior/posterior direction. The shear load simulates the net externalshear and active and passive soft tissue forces (see Fig. 4).3.1.9 subluxation load, nthe peak shear load required forsubluxation (for exampl
23、e, the peak resistive force at theglenoid articular rim opposing movement of the humeral head).3.1.10 subluxation translation, nthe distance from theglenoid origin (see Fig. 2), parallel to the glenoid plane, to thepoint at which the subluxation load occurs.3.1.11 superior/inferior (SI), nthe SI axi
24、s is the longestdimension of the glenoid component (see Fig. 2 and Fig. 3).FIG. 1 Glenosphere ThicknessF2028 142ANATOMIC SHOULDER GLENOID LOOSENINGTEST METHOD4. Summary of Test Method4.1 The prosthetic glenoid component is fixed with bonecement into a bone substitute using the normal surgicaltechniq
25、ue.4.2 The subluxation translation is determined experimen-tally on additional components. This is accomplished using abiaxial apparatus (see Fig. 5) by applying an axial loadperpendicular to the glenoid, then translating the humeral headparallel to the glenoid plane until encountering a peak shearl
26、oad. This is performed in both directions, corresponding 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 glen
27、oid, then the edge displacements are measured 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 practicalbecaus
28、e of the large displacements, quick speeds, and deform-able polyethylene).4.4 The humeral head is cycled to 90 % of the subluxationdistance for a fixed number of cycles.FIG. 2 Anatomic Glenoid Axes and OriginFIG. 3 Reverse Glenoid Baseplate AxesFIG. 4 Glenoid Plane and Load DirectionsF2028 1434.5 Th
29、e edge displacements (4.3) are either repeated follow-ing the cycling or measured continuously during the cycling.5. 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 tot
30、al shoulder arthro-plasty (see X1.1). The method assumes that loosening occursbecause of 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
31、 geometry, flangegeometry, materials, fixation design, bone quality, and surgicaltechnique.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. 4).
32、 Fig. 5FIG. 5 Biaxial Testing Apparatus for Anatomic ShouldersFIG. 6 Displacement Test ConfigurationF2028 144shows the axial load to be horizontal and the shear load to bevertical; however, this arrangement may be reversed.6.2 A bone substitute representing the strength or glenoidcancellous bone (se
33、e X1.5) shall be used. If a polyurethanefoam is used, it shall conform to Specification F1839.6.3 The glenoid and humeral head shall be enclosed in achamber with water heated to 37 6 2C, at least for thedynamic portion of the test (see X1.6). A buffer may be added,if the tester deems this necessary.
34、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 The tests shall be performed on either mechanical orhydraulic load frames with adequate load capacity and shallmeet the criteria o
35、f Practices E4.7. Sampling and Test Specimens7.1 A minimum of three samples shall be tested. Additionalsamples may be used to reflect test variability. At least twoadditional components should be used to determine the sub-luxation translation. The test may be conducted along thesuperior-inferior axi
36、s, 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 specifications forclinical use.7.3 The humeral head shall include the i
37、dentical 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 components are used in totalshoulder arthroplasty and should conform t
38、o the criteriaspecified in Specification F1378.8. 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 normal surgical procedure andinstrumentation. Do not perform tests
39、until the cement hascured properly.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 unnecessary for congruent prostheses. Locate thecenter of the path (for the
40、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 displacements) either in air at room temperature or inwater at 37C. The cycl
41、ic testing shall 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 6 7.5 N (see X1.4).8.2 Determine the subluxation translation experimentally onseparate components (see X1.2):8.2.1 After applying the axial load, displace the humeralhea
42、d at a constant rate to a given displacement, ensuring that apeak load is achieved in both directions. A rate of 50 mm/minis recommended to avoid polyethylene creep.8.2.2 Yielding is expected at the recommended load anddoes not constitute a failure. The test shall be terminated if theinsert of a mod
43、ular glenoid disassociates.FIG. 7 Alternative Displacement Test ConfigurationF2028 1458.2.3 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 ofthe glenoid at a similar dista
44、nce 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 bonesubstitute). Flatten the scre
45、w head parallel to the glenoid plane.Alternative methods are acceptable (see X1.8).8.3.2 Rest a displacement measuring device, for example, alinear variable differential transformer (LVDT), differentialvariable reluctance transducer (DVRT), or dial gauge, on eachfoundation to measure the displacemen
46、ts perpendicular to theglenoid plane (see X1.8). Continuous measurement isdesirable, but measurement at the beginning and end of therocking 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 humeral
47、head located at the glenoid origin (see Fig. 2 and Fig. 3).8.3.5 Translate the humeral 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 subluxationtr
48、anslation in the opposite direction and measure both edgedisplacements.8.3.7 Repeat the 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
49、as a result ofthe large translations, or up to a maximum of 6 Hz) to amaximum number of cycles (for example, 100 000) (see X1.7).Maintain the axial load and specified displacement.8.5 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 were 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 t
