Keynote Speech: "Predicting total hip replacement wear: recent in-silico developments combining synovial lubrication and multibody dynamics

The aim of this keynote was to show the latest research achievements obtained at the Department of Industrial Engineering of the University of Salerno by the research group leading by the Author, in the framework of the computational (bio) tribology and biomechanics applied to artificial human synovial joints. Main aim of the research was to accurately predict the in-silico wear of artificial implants, modelling the complex tribological phenomena acting in the joints due to the synovial lubrication considering unsteady loading of the joint. With reference to the Total Hip Replacements (THR), in this lecture were underlined recent computational approaches obtained by merging multibody models, solving the inverse dynamics of musculoskeletal systems, and synovial mixed elasto-hydrodynamic lubrication models. The effectiveness of the proposed analysis consists in the possibility of examining many physical activities, characterized by cyclic kinematic and loading joint conditions like running, swimming and sport in general, in order to predict the implant duration overcoming excessive time and money consumption due to the experimental set-up and investigation, moreover taking into account the complexity of a mixed lubrication model adaptable to several synovial fluid lubrication properties and that considers the surfaces’ contact. The achieved results, mainly in terms of wear volume prediction, were compared with respect to the in-vitro experiments developed by considering standardized (ISO 14242-3) joint loading. The obtained results were very promising, encouraging the research team toward the investigation and the development of more and more accurate models.