Significance and Use 4.1 This practice uses clinical radiographs of the hip joint of a patient that has received a total hip replacement to measure the combined effect of plastic deformation and wear at the articular interface which results in three-dimensional displacements of the femoral head into the acetabular component. 4.2 This practice addresses the validation of the various computational methods available for measuring the magnitude of creep/wear accruing at the articular surface of THRs. 4.3 This practice addresses the type of radiographic projections needed for an analysis as well as general radiographic parameters needed for obtaining high quality films. 4.4 This practice addresses the criterion for evaluating clinical radiographs for inclusion in a study. 4.5 This practice addresses the conversion of radiographic images to the appropriate digital format needed for the various computer-assisted computational methods.Scope 1.1 This practice provides guidance for the measurement of the relative displacement of the femoral head and acetabular component that result from wear and deformation occurring at the articular interface of a total hip replacement from sequential clinical radiographs. 1.2 This practice is primarily intended for use in evaluating patients receiving THRs composed of a polyethylene acetabular component articulating against a metal or ceramic femoral head. 1.3 So-called hard-on-hard articulations such as metal-on-metal and ceramic-on-ceramic THRs are not intended to be directly addressed. 1.4 This practice will focus on computer-assisted computational methodologies for measuring relative displacements over time but not to the exclusion of other methodologies. 1.5 This practice describes methods for conducting a radiographic wear/creep study utilizing various computational methods and is not intended to promote or endorse a particular method. 1.6 It is not the intent of this practice to provide detailed instructions in the use of the various computational methods, which is contained in the respective user manuals. 1.7 It is the intent of this practice to enable comparisons of relative displacements occurring in groups of patients receiving different formulations of bearing materials. It must be recognized, however, that there are many possible variations in the in vivo conditions. A single clinical study may not be universally representative. 1.8 This practice is not intended to be a performance standard. It is the responsibility of the user of this practice to characterize the safety and effectiveness of the prosthesis under evaluation. 1.9 The values stated in SI units are to be regarded as the standard, with the exception of angular measurements, which may be reported in either degrees or radians. Additionally, pixel density may also be reported in imperial units. 1.10 The use of this standard may involve the operation of potentially hazardous radiographic equipment and does not purport to address the safety precautions associated with radiography. It is the responsibility of the user of this standard to define and establish appropriate safety practices. The standard does not determine the applicability of regulatory limitations prior to operating radiographic equipment. 1.11 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.12 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.
