ASTM F2003-00
(Guide)Standard Guide for Accelerated Aging of Ultra-High Molecular Weight Polyethylene
Standard Guide for Accelerated Aging of Ultra-High Molecular Weight Polyethylene
SCOPE
1.1 It is the intent of this guide to permit an investigator to investigate the oxidative stability of ultra-high molecular weight polyethylene (UHMWPE) materials as a function of processing and sterilization method. This guide describes a laboratory test method for accelerated aging of UHMWPE specimens and components for total joint prostheses. The UHMWPE is aged at elevated temperatures and, alternatively, at elevated partial pressures of oxygen, to accelerate oxidation of the material and thereby allow for the evaluation of its long-term chemical and mechanical stability.
1.2 Although the accelerated-aging test methods described by this guide will permit an investigator to compare the oxidative stability of UHMWPE, it is recognized that these test methods may not precisely simulate the degradative mechanisms for an implant during real-time shelf aging and implantation. However, these accelerated oxidation methods have been successfully used to rank UHMWPE materials for their long-term oxidative stability.
1.3 The accelerated aging test methods specified herein have been validated based on oxidation levels exhibited by certain shelf-aged UHMWPE components packaged in air and sterilized with gamma radiation. The methods have not been shown to be representative of shelf aging when the UHMWPE is packaged in an environment other than air. For example, these test methods have not been directly correlated with the shelf life of components that have been sealed in a low-oxygen package, such as nitrogen.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
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Designation: F 2003 – 00
Standard Guide for
Accelerated Aging of Ultra-High Molecular Weight
Polyethylene
This standard is issued under the fixed designation F 2003; 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.
1. Scope ethylene Powder and Fabricated Form Surgical Implants
F 1714 Guide for Gravimetric Wear Assessment of Pros-
1.1 It is the intent of this guide to permit an investigator to
thetic Hip-Designs in Simulator Devices
investigate the oxidative stability of ultra-high molecular
F 1715 Guide for Gravimetric Wear Assessment of Pros-
weight polyethylene (UHMWPE) materials as a function of
thetic Knee-Designs in Simulator Devices
processing and sterilization method. This guide describes a
2.2 ISO Standards:
laboratory test method for accelerated aging of UHMWPE
ISO 5834 Implants for surgery—Ultra-high molecular
specimens and components for total joint prostheses. The
weight polyethylene
UHMWPE is aged at elevated temperatures and, alternatively,
ISO 14242 Implants for surgery—Wear of total hip joint
at elevated partial pressures of oxygen, to accelerate oxidation
prostheses
of the material and thereby allow for the evaluation of its
ISO 14243 Implants for surgery—Wear of total knee joint
long-term chemical and mechanical stability.
prostheses
1.2 Although the accelerated-aging test methods described
by this guide will permit an investigator to compare the
3. Terminology
oxidative stability of UHMWPE, it is recognized that these test
3.1 Definitions—For definitions of terms in this guide relat-
methods may not precisely simulate the degradative mecha-
ing to plastics, refer to Terminology D 883. For definitions of
nisms for an implant during real-time shelf aging and implan-
terms in this guide relating to UHMWPE, refer to Specification
tation. However, these accelerated oxidation methods have
F 648 and ISO 5834.
been successfully used to rank UHMWPE materials for their
3.2 Definitions of Terms Specific to This Standard:
long-term oxidative stability.
3.2.1 oxidation, n—the incorporation of oxygen into an-
1.3 The accelerated aging test methods specified herein
other molecule (for example, UHMWPE) by means of a
have been validated based on oxidation levels exhibited by
chemical covalent bond.
certain shelf-aged UHMWPE components packaged in air and
3.2.2 oxygen bomb, n—a pressure vessel suitable for pre-
sterilized with gamma radiation. The methods have not been
conditioning of UHMWPE at an elevated temperature and
shown to be representative of shelf aging when the UHMWPE
partial pressure of oxygen.
is packaged in an environment other than air. For example,
these test methods have not been directly correlated with the
4. Significance and Use
shelf life of components that have been sealed in a low-oxygen
4.1 This guide summarizes test methods that may be used to
package, such as nitrogen.
accelerate the oxidation of UHMWPE components using
1.4 This standard does not purport to address all of the
elevated temperatures and, alternatively, elevated partial pres-
safety concerns, if any, associated with its use. It is the
sures of oxygen. Under real-time conditions, such as shelf
responsibility of the user of this standard to establish appro-
aging and implantation, oxidative changes to UHMWPE after
priate safety and health practices and determine the applica-
sterilization using high energy radiation may take months or
bility of regulatory limitations prior to use.
years to produce changes that may result in deleterious
mechanical performance. The test methods outlined in this
2. Referenced Documents
guide permit the evaluation of oxidative stability in a relatively
2.1 ASTM Standards:
2 short period of time (for example, weeks).
D 883 Terminology Relating to Plastics
4.2 This guide may also be used to precondition UHMWPE
F 648 Specification of Ultra-High Molecular-Weight Poly-
test specimens and joint replacement components prior to
characterization of their physical, chemical, and mechanical
This guide is under the jurisdiction of ASTM Committee F-4 on Medical and
Surgical Materials and Devices and is the direct responsibility of Subcommittee
F04.15 on Test Material Methods.
Current edition approved Jan. 10, 2000. Published April 2000. 3
Annual Book of ASTM Standards, Vol 13.01.
Annual Book of ASTM Standards, Vol 08.01. 4
Available from American National Standards Institute, 11 W. 42nd St., 13th
Floor, New York, NY 10036.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
F 2003
NOTE 2—To maximize the extent and penetration of oxidative degra-
properties. In particular, this guide may be used for precondi-
dation into bulk hip or knee components using Test Method A, it is
tioning of UHMWPE components prior to evaluation in a hip
recommended that specimens be inserted into the thermal chamber while
or knee joint wear simulator as outlined in Guide F 1714 (hip
at room temperature, and that the chamber be elevated to the constant
wear), Guide F 1715 (knee wear), ISO 14242 (hip wear), or
preconditioning temperature at a slow constant heating rate, ranging from
ISO 14243 (knee wear), or combination thereof. 5
0.1 to 0.6°C/min (1).
5. Apparatus and Materials 6.2 Test Method B (Preconditioning at Elevated Partial
Pressures of Oxygen)—Conduct Test Method B using an
5.1 UHMWPE Test Specimens—The test specimens shall be
oxygen bomb placed inside a suitable thermal chamber. Pre-
prepared in final form in accordance with the requirements of
condition test specimens at a constant temperature of 70°C and
any subsequent physical, chemical, or mechanical tests to be
at an equilibrium pressure of 503 kPa (73 psi, 5 atmospheres)
performed after preconditioning. For example, if the specimens
of pure oxygen for 2 weeks prior to subsequent testing.
will ultimately be subjected to hip joint simulation, they should
6.3 Regardless of the preconditioning test method used
be prepared in final form in accordance with Guide F 1714 and
(Test Method A or B), array the test specimens within the test
ISO 14242. Because the accelerated oxidation methods out-
chamber or oxygen bomb such that all relevant surfaces have
lined in this guide result in inhomogeneous distribution of
equivalent access to oxygen during the test. For example, with
chemical, physical, and hence mechanical properties through
hip and knee components, the articulating surface which may
the thickness of a preconditioned part, it is not recommended
subsequently be subjected to wear simulation shall not be
that finished test specimens be machined after preconditioning
obstructed or covered by other parts or materials that might
of (bulk) stock materials. Because this guide is not intended to
interfere with uniform access of the surface to oxygen.
reproduce the aging of UHMWPE that is stored in a low-
6.4 For both Test Methods A and B, maintain the test
oxygen environment, test specimens should be removed from
chamber or oxygen bomb, or both, at ambient humidity. The
their packaging prior to preconditioning.
user should be aware that adding water to the test chamber may
5.2 Preconditioning Chamber—Accelerated oxidation (pre-
affect the oxidation mechanism during the preconditioning
conditioning) of the UHMWPE shall be conducted in a
process.
convection, air circulating oven that can maintain the desired
temperature with an accuracy of 62°C. The spatial variation of
7. Report of Specimen Preparation and Test Conditions
temperature within the oven
...
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