1.1 This practice describes the testing, analytical, and characterization methods for evaluating the stability of the bore and cone interface of the head and stem junction of modular hip implants subjected to cyclic loading in a corrosive environment by measurements of fretting corrosion test methods described are as follows: 1.1.1 Method IThe primary purpose of this method is to provide a uniform set of guidelines to accelerate fretting corrosion in long-term testing to determine the amount of damage by post test evaluation and electrochemical characterization during the test. Damage is also assessed by characterization of the surfaces and geometry of the bore and cone before and after the testing 1.1.2 Methods IIThis 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 1.2 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 simulated head/neck taper 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 simulated head/neck taper identical in design, manufacturing, and materials to the taper of the final hip implant 1.4 The general concepts and methodologies described in this practice could be applied to the study of other modular interfaces in total joint prostheses. 1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.6 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.
This practice can be used to rank the effects of head and cone materials, design variables, manufacturing, and other conditions on the resistance to fretting corrosion under cyclic forces in a simulated human body environment. These test methods shall use the modular femoral components that meet the full requirements of the modular components of actual femoral prostheses. The materials and processing shall be the same as the final finished products with the exception of sterilization. The test may reveal features of materials, material combinations, designs, and manufacturing processes that work to inhibit the occurrence of crevice corrosion. In the fatigue test methods, it is recognized that actual loading in vivo is quite varied and that no one set of experimental conditions can encompass all possible variations. Thus, the test methods included here represent a simplified model for the purposes of comparisons between designs and materials. The environment is representative of the saline environment for the femoral prosthesis in the human body with the exception that the reactivity of the environment is accelerated by increasing the temperature higher than the normal temperature of the human body and using acid to decrease the pH of the environment to accelerate the decrease in pH than can occur in crevices with metallic surfaces.
Keywordsfatigue; fretting; fretting corrosion; hip; modular; taper; adapter; sleeve; crevicecorrosion; modular heads; modular tapers and bores; potentiostatic current monitoring
The title and scope are in draft form and are under development within this ASTM Committee.Back to Top
Draft Under Development