Standard Practice for Gravimetric Measurement of Polymeric Components for Wear Assessment

Abstract

3.1 This practice uses a weight loss method of wear determination for the polymeric components or materials used in human joint prostheses using serum or demonstrated equivalent fluid for lubrication and running under a load profile representative of the appropriate human joint application (1, 2).4 The basis for this weight loss method for wear measurement was originally developed (3) for pin-on-disk wear studies (Test Method F732) and has been extended to total hip replacements (4, 5) (ISO 14242-2, Guide F1714), to femoro-tibial knee prostheses (6) (ISO 14243-2), and to femoro-patellar knee prostheses (6, 7). 3.2 While wear results in a change in the physical dimensions of the specimen, it is distinct from dimensional changes due to creep or plastic deformation, in that wear results in the removal of material in the form of polymeric debris particles, causing a loss in weight of the specimen. 3.3 This practice for measuring wear of the polymeric component is suitable for various simulator devices. These techniques can be used with metal, ceramic, carbon, polymeric, and composite counterfaces bearing against a polymeric material (for example, polyethylene, polyacetal, and so forth). Thus, this weight loss method has universal application for wear studies of human joint replacements which feature polymeric bearings. This weight loss method has not been validated for non-polymeric material bearing systems such as metal-metal, carbon-carbon, or ceramic-ceramic. Progressive wear of such rigid bearing combinations has generally been monitored using linear variable displacement transducers, or by other profilometric techniques.