ASTM F3129 : 24

1.1 This guide specifies a method to measure the surface features, such as hills and valleys, and to 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 includes information on how to perform measurements using a Roundness Machine (1-4), Coordinate Measuring Machine (CMM) (5), and Optical Coordinate Measuring Machine (6, 7).2 Other equipment may be used to estimate material loss if the equipment is reliable and accurate enough to provide comparable estimates to the aforementioned equipment.

1.3 The measurement techniques described in this standard guide use measurements taken on the surface of the taper using contact stylus and/or optical instruments. The mating materials and geometries in the taper junction can have changed in form, structure, and composition during use. These changes will impact any final estimation. In addition, any estimation of original surface form will also impact any final estimation of material loss. The material loss/corrosion mechanisms in the taper junction can lead to oxide layers or corrosion products on the surface of the taper. These layers can lead to an underestimation of the volume of material loss.

1.4 The explants can have debris or biological deposits on the surfaces of the taper junctions. These deposits can prevent the measurement of the surface of the taper junction, and their effect on the measurement must be considered when deciding the cleaning protocol.

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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.6 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.