This paper presents a metrological analysis of hip prosthesis components. When changing ceramic prostheses, the surgeon sometimes finds traces of alloy lying in the insert or the femoral head. These traces can be thin and accurate or as a wide band. From the measurements made on the contact areas of hip prosthesis components, we analyse these phenomena by highlighting the defects of form, waviness and roughness of these surfaces using a novel geometric parameterization (namely modal parameterization). The aim of this work is to isolate these defects to characterize the prostheses components. We show that this parameterization allows a multi-scale analysis of surfaces regardless of the type of wear of the prosthesis, and that the results offer some relevant explanations to the analysis of visible damage on the prostheses. In a later study, we are going to analyse the defects influence on the alteration of the performance of hip prostheses.