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.