1.1   This standard guide provides options and a compendium of information for measuring the bearing surface and estimating the in-vivowear of explanted Metal-on-Metal (MoM) and other “hard” (for example, ceramic) hip components. The guide covers the measurement of acetabular cups and femoral heads using a dimensional change method and is applicable to all prosthetic hip types, including stemmed (modular) and resurfacing hip systems.