ASTM F1672-95e1
(Specification)Standard Specification for Resurfacing Patellar Prosthesis
Standard Specification for Resurfacing Patellar Prosthesis
SCOPE
1.1 This specification covers patellar resurfacing devices used to provide a functioning articulation between the bones of the patella and the femur.
1.2 This specification is intended to provide basic descriptions of material and device geometry. Additionally, those characteristics determined to be important to in-vivo performance of the device are defined.
1.3 This specification does not cover the details for quality assurance, design control, and production control contained in 21 CFR 820 and ISO 9001.
Note 1--Devices for custom applications are not covered by this specification.
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Standards Content (Sample)
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e1
Designation: F 1672 – 95
Standard Specification for
Resurfacing Patellar Prosthesis
This standard is issued under the fixed designation F 1672; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
e NOTE—Editorial changes were made throughout in December 1996.
1. Scope ethylene Powder and Fabricated Form for Surgical Im-
plants
1.1 This specification covers patellar resurfacing devices
F 732 Practice for Reciprocating Pin-on-Flat Evaluation of
used to provide a functioning articulation between the bones of
Friction and Wear Properties of Polymeric Materials for
the patella and the femur.
Use in Total Joint Prostheses
1.2 This specification is intended to provide basic descrip-
F 745 Specification for 18 Chromium-12.5 Nickel-2.5 Mo-
tions of material and device geometry. Additionally, those
lybdenum Stainless Steel for Cast and Solution— Annealed
characteristics determined to be important to in-vivo perfor-
Surgical Implant Applications
mance of the device are defined.
F 746 Test Method for Pitting or Crevice Corrosion of
1.3 This specification does not cover the details for quality
Metallic Surgical Implant Materials
assurance, design control, and production control contained in
F 748 Practice for Selecting Generic Biological Test Meth-
21 CFR 820 and ISO 9001.
ods for Materials and Devices
NOTE 1—Devices for custom applications are not covered by this
F 799 Specification for Cobalt-28 Chromium-6 Molybde-
specification.
num Alloy Forgings for Surgical Implants
F 981 Practice for Assessment of Compatibility of Bioma-
2. Referenced Documents
terials for Surgical Implants with Respect to Effect of
2.1 ASTM Standards:
Materials on Muscle and Bone
F 75 Specification for Cast Cobalt-Chromium-Molybdenum
F 983 Practice for Permanent Marking of Orthopaedic Im-
Alloy for Surgical Implant Applications
plant Components
F 86 Practice for Surface Preparation and Marking of Me-
F 1044 Test Method for Shear Testing of Porous Metal
tallic Surgical Implants
Coatings
F 90 Specification for Wrought Cobalt-Chromium-Nickel-
F 1108 Specification for Ti6Al4V Alloy Castings for Surgi-
Tungsten Alloy for Surgical Implant Applications
cal Implants
F 136 Specification for Wrought Titanium 6Al-4V ELI
F 1147 Test Method for Tension Testing of Porous Metal
Alloy for Surgical Implant Applications
Coatings
F 138 Specification for Stainless Steel Bar and Wire for
2.2 Government Document:
Surgical Implants (Special Quality)
21 CFR 820-Good Manufacturing Practice for Medical
F 451 Specification for Acrylic Bone Cement
Devices
F 562 Specification for Wrought Cobalt-35 Nickel 20-
2.3 ISO Standard:
Chromium 10-Molybdenum Alloy for Surgical Implant
ISO 9001-Quality Systems-Model for Quality Assurance in
Applications
Design/Development, Production, Installation, and Ser-
F 563 Specification for Wrought Cobalt-Nickel-Chromium-
vicing
Molybdenum-Tungsten-Iron Alloy for Surgical Implant
Applications
3. Terminology
F 603 Specification for High-Purity Dense Aluminum Ox-
3.1 Definitions—Dimensions defined as follows are mea-
ide for Surgical Implant Applications
sured in whole or in part in the sagittal, transverse, and coronal
F 648 Specification for Ultra-High-Molecular-Weight Poly-
(or frontal) planes as appropriate. See Fig. 1 and Fig. 2.
3.1.1 T —total overall prosthetic thickness, for example,
1 3
This specification is under the jurisdiction of ASTM Committee F-4 on Medical Discontinued; see 1994 Annual Book of ASTM Standards, Vol 13.01.
and Surgical Materials and Devices and is under the direct responsibility of Available from Superintendent of Documents, U.S. Government Printing
Subcommittee F04.22 on Arthroplasty. Office, Washington, DC 20402.
Current edition approved Nov. 10, 1995. Published May 1996. Available from American National Standards Institute, 11 W. 42nd St., 13th
Annual Book of ASTM Standards, Vol 13.01. Floor, New York, NY 10036.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
F 1672
tended to increase the surface contact or mechanical interlock
between the component, the bonding agent (bone cement) or
the natural patella, or both.
3.2.3 marker wire—a nonstructural, generally thin metallic
wire, designed to be apparent on X-rays taken after placement
of implants that otherwise would be nonapparent on such
X-rays.
3.2.4 metal back—a metal structure supporting the articu-
lating surface material. This may be fixed rigidly to the
articulating surface or it may be fixed such that it allows the
(a) (b) (c)
articulating surface to rotate or translate.
3.2.5 radii of curvature—the geometry of the articular
NOTE 1—Figure 1(a) and (b) show a dome style and Fig. 1(c) shows a
surface may be described by a list of appropriate radii of
sombrero style.
curvature.
FIG. 1 Two Versions of Axisymmetric Patella Prostheses
3.2.6 sombrero—a style of axisymmetric prosthesis that has
multiple radii of curvature. (See Fig. 1Fig. 1c.)
4. Classification
4.1 Patellar replacement devices may be classified accord-
ing to geometry:
4.1.1 Axisymmetric—The articulating surface is symmetric
on an axis perpendicular to the prepared bonding surface (for
(a) Transverse Cross Section With (b) Sagittal Cross Section
example, Dome patellas and sombrero-type patellas). See Fig.
Lateral to the Right
1.
FIG. 2 Example of a Nonsymmetric Patella Prosthesis
4.1.2 Nonsymmetric—The articulating surface is not axi-
symmetric but may be symmetric on a plane. Examples of this
from the apex of the dome to the free end of pegs or other
type are anatomical or oblong prosthesis. See Fig. 2.
fixation geometry.
4.2 It is important to define the type of fixation geometry so
3.1.2 T —thickness of the patellar prosthesis from the plane
that the user can understand the degree of bone invasion:
of the bone-prosthesis interface (excluding pegs, keels, and so
4.2.1 Peg—Number, size (for example: length, width, di-
forth) to the apex of the articulating surface.
ameter, and so forth), and location and
3.1.3 T —minimum polymer thickness of the patellar pros-
4.2.2 Keel—Width, length, thickness, geometry, and loca-
thesis in direct contact with the femoral component that is “at
tion.
risk” for wear; this is measured perpendicular to the tangent of
5. Materials and Manufacture
the wear surface at the point of contact with the femoral
component.
5.1 The choice of materials is understood to be a necessary
3.1.4 Discussion—The dimension T is described in Fig. 1 but not sufficient ensurance of function of the device made
and Fig. 2 to be a distance from a surface contact point to an
from them. All devices conforming to this specification shall be
internal peg or an edge of the metal back. The exact location of fabricated from materials, with adequate mechanical strength
the minimum thickness at risk may be at a different site and
and durability, corrosion resistance and biocompatibility.
will depend on the design of the patella prosthesis and the 5.1.1 Mechanical Strength—Components of various pros-
mating femoral component. For devices manufactured from a
theses have been successfully fabricated from the following
single material, T should be measured from the wear surface materials. See Specifications F 75, F 90, F 136, F 138, F 562,
to the back of the fixation surface.
F 563, F 603, F 648, F 745, F 799, and F 1108. The articulating
3.1.5 W —maximum medial-lateral width of the articulat- surface should be fabricated from a material such as UHM-
ing surface in the frontal plane.
WPE in accordance with Specification F 648.
3.1.6 W —maximum medial-lateral width of the metal back 5.1.2 Corrosion Resistance—Materials with limited or no
in the frontal plane.
history of successful use for orthopedic implant application
3.1.7 H —articulating surface superior-inferior height in the must be determined to exhibit corrosion resistance equal to or
frontal plane.
better than one of the materials listed in 5.1.1 when tested in
3.1.8 H —metal back superior-inferior height in the frontal accordance with Test Method F 746.
plane.
5.1.3 Biocompatibility—Materials with limited or no his-
3.1.9 Rc—radius of curvature for single radius axisymmet-
tory of successful use for orthopedic implant application must
ric domes only.
be determined to exhibit acceptable biological response equal
3.2 Definitions of Terms Specific to This Standard:
to or better than one of the materials listed in 5.1.1 when tested
3.2.1 dome—a style of axisymmetric prosthesis that has a in accordance with Practices F 748 and F 981.
single uniform radius of curvature (that is, button).
6. Performance Requirements
3.2.2 fixation element—any peg, keel, or other protrusion
from the nonarticulating side of the patellar component in- 6.1 The implant shall be capable of withstanding sustained
F 1672
NOTE 2—In situations where the pin-on-flat test may not be considered
static and dynamic physiologic loads without compromise of
appropriate, other test methods may be considered.
its function for the intended use and environment. At this time
there are no device-specific test methods and there are no
6.5 Porous metal coatings shall be tested according to Test
acceptable performance levels. Device testing shall be done in
Method F 1044 (shear strength) and Test Method F 1147
keeping with the implant’s intended function.
(tensile strength).
6.2 There
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