EP3.20 Shear-Enhanced Discrete Element Analysis of Hip Cartilage Contact in Femoroacetabular Impingement

Abstract Abnormal joint mechanics play a central role in hip pathology in young adults, particularly in conditions such as femoroacetabular impingement (FAI). In these patients, altered contact mechanics can increase contact pressures and generate shear stresses. These shear stresses are believed to contribute to cartilage delamination, a key clinical feature of FAI. A better understanding of these mechanical processes is essential for improving diagnosis and treatment. Computational modeling offers a valuable way to investigate them. Finite element analysis (FEA) is the reference standard for evaluating contact pressure and shear stresses. However, its high computational cost limits its use in large-scale and subject-specific analyses. Discrete element analysis (DEA) is a faster alternative. DEA represents cartilage contact using distributed springs between articulating surfaces. Conventional DEA models are limited to normal contact and do not capture shear-driven interactions, which are important in FAI. To address this limitation, a shear-enhanced DEA framework is introduced for modeling articular cartilage contact. The proposed approach extends the classical spring-based formulation by incorporating tangential contact behavior through a friction-based model and tangential response. This enables the estimation of contact pressure and shear traction while preserving the computational efficiency needed for subject-specific simulations. This method was developed to better represent the mechanical causes of cartilage damage in FAI. In particular, current fast computational models do not capture shear-induced cartilage delamination, a key clinical feature. Ongoing comparisons with corresponding FEA simulations aim to evaluate whether the proposed method can reproduce key trends in contact pressure distribution and shear response. By incorporating shear into DEA, this approach has the potential to combine computational efficiency with clinical relevance. It may provide a practical tool for improving understanding, diagnosis, and treatment planning in hip pathology.