1.1 This guide specifies a method to measure the surface and estimate the in-vivo material loss from the conical taper junctions, such as the femoral head/stem junction or adapter sleeve from explanted modular hip prosthesis, modular knee or shoulder joints. This guide is applicable to any articulating bearing material, stem material and conical taper size. The principles in this guide may be applied to other designs of taper junction, such as the modular stem/neck junction found in some hip joints.

1.2 This guide covers the measurement of the surface and estimation of depth of material loss and volume of material loss and taper geometry using a Roundness Machine (1-4), Coordinate Measuring Machine (CMM) (5) and Optical Coordinate Measuring Machine (6, 7).2 Other measurement equipment may be used to measure the surface if the resolution and accuracy of the measurements are comparable with the instruments detailed in this standard. The measurement and analysis protocols should be based on those described in this standard.

Note 1: The maximum depth of material loss is sensitive to the number and spacing of data points.

1.3 The measurement techniques in this standard guide use measurements taken on the surface of the taper using stylus instruments. The material loss/corrosion mechanisms in the taper junction may lead to oxide layers or corrosion products deposited on the surface of the taper. These layers may lead to an underestimation of the volume of material loss.

1.4 The explants may have debris or biological deposits on the surfaces of the taper junctions. These deposits will prevent the measurement of the actual surface of the taper junction and their effect on the measurement must be considered when deciding the cleaning protocol. Normally, the taper surfaces will be cleaned before measurements are taken.

1.5 This standard may involve hazardous materials, operations and equipment. As a precautionary measure, explanted devices should be sterilized or minimally disinfected by an appropriate means that does not adversely affect the implant or the associated tissue that may be the subject of subsequent analysis. A detailed discussion of precautions to be used in handling human tissues can be found in ISO 12891-1. 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.