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1.1 This practice describes a laboratory method using a weight-loss (that is, mass-loss; see X1.4) technique for evaluating the wear properties of polymeric materials or devices which are being considered for use as bearing surfaces of human joint replacement prostheses. The test specimens are evaluated in a device intended to simulate the tribological conditions encountered in the human joint; for example, use of a fluid such as bovine serum, or equivalent pseudosynovial fluid shown to simulate similar wear mechanisms and debris generation found in vivo.

1.2 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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 (Practice F732) and has been extended to total hip replacements (4, 5, ISO 14242–2, and Guide F1714), and to femoro-tibial knee prostheses (6 and 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 counter faces 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.