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Significance and Use
The modular interfaces of total joint prostheses are subjected to micromotion that could result in fretting and corrosion. The release of corrosion products and particulate debris could stimulate adverse biological reactions, as well as lead to accelerated wear at the articulation interface. Methods to assess the stability and corrosion resistance of the modular interfaces, therefore, are an essential component of device testing.
Long-term in-vitro testing is essential to produce damage and debris from fretting of a modular interface (4,5). The use of proteinaceous solutions is recommended to best simulate the in-vivo environment.
Short-term tests often can be useful in evaluations of differences in design during device development (1-4). The electrochemical methods provide semiquantitative measures of fretting corrosion rates. The relative contributions of mechanical and electrochemical processes to the total corrosion and particulate release phenomena, however, have not been established; therefore, these tests should not be utilized to compare the effects of changes in material combinations, but rather be utilized to evaluate design changes of bore (head) and cone (stem) components.
These tests are recommended for evaluating the fretting wear and corrosion of modular interfaces of hip femoral head and stem components. Similar methods may be applied to other modular interfaces where fretting corrosion is of concern.
These methods are recommended for comparative evaluation of the fretting wear and corrosion of new materials, coatings, or designs, or a combination thereof, under consideration for hip femoral head and neck modular interfaces. Components for testing may be those of a manufactured modular hip device (finished product) or sample coupons, which are designed and manufactured for simulation of the head, taper, and neck region of a modular hip device.
1.1 This practice describes the testing, analytical, and characterization methods for evaluating the mechanical stability of the bore and cone interface of the head and stem junction of modular hip implants subjected to cyclic loading by measurements of fretting corrosion (1-5). Two test methods described are as follows:
1.1.1 Method I—The primary purpose of this method is to provide a uniform set of guidelines for long-term testing to determine the amount of damage by measurement of the production of corrosion products and particulate debris from fretting and fretting corrosion. Damage is also assessed by characterization of the damage to the bore and cone surfaces (4, 5).
1.1.2 Methods II—This method provides for short-term electrochemical evaluation of the fretting corrosion of the modular interface. It is not the intent of this method to produce damage nor particulate debris but rather to provide a rapid method for qualitative assessment of design changes which do not include material changes (1-4).
1.2 This practice does not provide for judgment or prediction of in-vivo implant performance, but rather provides for a uniform set of guidelines for evaluating relative differences in performance between differing implant designs, constructs, or materials with performance defined in the context of the amount of fretting and fretting corrosion. Also, this practice should permit direct comparison of fretting corrosion data between independent research groups, and thus provide for building of a data base on modular implant performance.
1.3 This practice provides for comparative testing of manufactured hip femoral heads and stems and for coupon type specimen testing where the male taper portion of the modular junction does not include the entire hip implant, with the taper portion of the coupon identical in design, manufacturing, and materials to the taper of the final hip implant (4,5).
1.4 Method I of this practice permits simultaneous evaluation of the fatigue strength of a femoral hip stem (in accordance with Practice F1440) and the mechanical stability and debris generated by fretting and fretting corrosion of the modular interface.
1.5 The general concepts and methodologies described in this practice could be applied to the study of other modular interfaces in total joint prostheses.
1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.7 This standard may involve hazardous materials, operations, and equipment. 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.
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
E4 Practices for Force Verification of Testing Machines
E466 Practice for Conducting Force Controlled Constant Amplitude Axial Fatigue Tests of Metallic Materials
E467 Practice for Verification of Constant Amplitude Dynamic Forces in an Axial Fatigue Testing System
F561 Practice for Retrieval and Analysis of Medical Devices, and Associated Tissues and Fluids
F746 Test Method for Pitting or Crevice Corrosion of Metallic Surgical Implant Materials
F897 Test Method for Measuring Fretting Corrosion of Osteosynthesis Plates and Screws
F1440 Practice for Cyclic Fatigue Testing of Metallic Stemmed Hip Arthroplasty Femoral Components Without Torsion
F1636 Specification for Bores and Cones for Modular Femoral Heads
G3 Practice for Conventions Applicable to Electrochemical Measurements in Corrosion Testing
G5 Reference Test Method for Making Potentiostatic and Potentiodynamic Anodic Polarization Measurements
G15 Terminology Relating to Corrosion and Corrosion Testing
G40 Terminology Relating to Wear and Erosion
G61 Test Method for Conducting Cyclic Potentiodynamic Polarization Measurements for Localized Corrosion Susceptibility of Iron-, Nickel-, or Cobalt-Based Alloys
G102 Practice for Calculation of Corrosion Rates and Related Information from Electrochemical Measurements
ISO StandardsISO7206-7 Endurance Performance of Stemmed Femoral Components Without Application of Torsion Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036.
ICS Number Code 11.040.40 (Implants for surgery, prothetics and orthotics)
UNSPSC Code 42321700(Hip joint implants)