This book aims to expand the knowledge on how surfaces from human joints behave. Factors under the scope are: friction coefficient and surface charges. Friction coefficient becomes vital as it changes along an individual's life; it is directly connected to tear and wear of cartilage tissue due to aging and diseases. Electrostatic charge of surfaces, are the ones governing biological interactions (e.g. protein adsorption and cell adhesion) and play a critical role in interaction of the body with biomaterials from prosthetic joint replacements. To get an insight on friction coefficient and surface charges in human joints, experiments were performed in samples obtained from animal models. Total joint replacement is a field where tribology plays a vital role. The efforts in this study are focused on the pursue of scientific information which leads to improvements for current treatments for diseased joints, before joint replacement to occur, and, moreover, for the cases in which jointreplacement is inevitable, to design and construct better prosthetic devices.