The standard “ASTM F1714-96 Standard guide for gravimetric wear evaluation of prosthetic hip designs in simulator devices” developed by the American Society for Testing and Materials (ASTM) describes a test method that uses a weight-loss technique to evaluate the wear characteristics of materials or devices, or both, intended for use as bearing surfaces for human hip joint replacement prostheses.
Hip prostheses are evaluated in a device intended to simulate the tribological conditions encountered in the human hip joint. Because the hip simulator method allows the use of actual implant designs, materials, and physiological load/motion combinations, it can represent a more physiological simulation than basic wear screening tests such as pin-disc (ASTM F732-00) or ring-disc (ISO 6474).
The purpose of this guide is to rank combinations of implant designs and materials in terms of material wear rates under simulated physiological conditions. However, there are many possible variations under in vivo conditions, and a single laboratory simulation with a fixed set of parameters may not be universally representative.
Reference materials for comparative evaluation of candidate materials, new devices or components, or a combination thereof shall be the wear rate of extruded or compression molded, ultra-high molecular weight polyethylene, tested against standard counter surfaces (stainless steel, cobalt chrome-molybdenum alloy, thermomechanically treated cobalt chrome, alumina ceramic), having typical prosthetic quality, surface finish, and geometry similar to those with established clinical history. These reference materials are tested under the same wear conditions as the candidate materials.
This guideline uses a weight-loss method of determining wear for polymeric components used with hip joint prostheses, using serum or proven equivalent fluid and operating under a dynamic load profile representative of human hip joint forces during walking.
The basis of this weight-loss method for wear measurement was originally developed for studies of pin wear on the disc and has been extended to total hip prostheses and femoral-tibial knee prostheses and femoropatellar knee prostheses.
Although wear causes a change in the physical dimensions of the sample, it differs from dimensional changes caused by creep or plastic deformation in that wear results in the removal of material, usually in the form of polymeric debris particles, resulting in a loss in weight of the sample.
This guideline for measuring polymeric component wear is suitable for a variety of simulator devices. These techniques can be used with metal, ceramic, carbon, polymeric, and composite counter surfaces against a polymeric material (e.g., polyethylene, polyacetal, and similar). Therefore, this weight loss method has universal application for wear studies of total hip prostheses with polymeric bearings. This weight loss method has not been validated for high-density material bearing systems such as metal-metal, carbon-carbon, or ceramic-ceramic. The gradual wear of such rigid bearing combinations has generally been monitored using linear, variable displacement transducers, or other profilometric techniques.
Hip replacement components, hip joint prosthesis consists of a ball and socket configuration where materials such as polymers, composites, metal alloys, ceramics and carbon are used in various combinations and designs.
During testing, components are kept in separate, isolated chambers on a multiple sample machine to prevent contamination of one set of components with debris from another test. The chamber should be constructed entirely of non-corrosive materials such as acrylic plastic or stainless steel and should be easily removable from the machine for thorough cleaning between tests. Wear chambers are designed so that the test bed surfaces remain immersed in lubricant throughout the test).
Since wear will be determined from the weight loss of the components, the method of mounting the components in the test chamber should not compromise the accuracy of the assessment of weight loss due to wear.
Among the numerous testing, measurement, analysis and evaluation studies that our organization has provided for businesses in various sectors, our organization also provides testing services defined in the standard “ASTM F1714-96 Standard guide for gravimetric wear assessment of prosthetic hip designs in simulator devices” with its trained and expert staff and advanced technological equipment.
To get an appointment, to get more detailed information or to request an evaluation, you can ask us to fill in our form and reach you.
