Adapting geometry for the development of an elastic foundation (EF) hip cartilage contact pressure model and a novel method of generating three-dimensional hip joint cartilage geometry

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Presenter(s)

Spencer Williams

Abstract or Description

Articular cartilage damage in the hip joint is associated with changes in cartilage contact pressure, but this quantity is often estimated using computationally expensive finite element analysis (FEA) methods. These models can require a significant time investment and may be unable to model more complex motions than walking. An elastic foundation (EF) model has been used as an alternative in the knee joint to avoid these limitations. I worked with Dr. Brecca Gaffney to develop an EF model for cartilage contact pressure in the hip. I supported the development of this model by positioning and scaling subject-specific proximal femur and cartilage geometry, generated from segmented CT arthrograms, from previously published FEA models to the OpenSim coordinate space and updating muscle insertion points on the subject-specific femurs. Dr. Gaffney built and validated the EF model by comparing its results processed using the Concurrent Optimization of Muscle Activations and Kinematics (COMAK) algorithm to the FEA results. This model will be used to estimate contact pressures for other subjects, which I have generated cartilage surfaces for using Amira software. Because MR images are available for these subjects but not CT arthrograms, different methods from those used in the FEA models are required for modeling the cartilage geometry, and I have prepared surfaces to represent acetabular cartilage with two methods; the first is based on published models with a constant cartilage thickness, and the second attempts to account for the variations in acetabular cartilage thickness reported in literature using original methods. Femoral head cartilage was modeled with constant thickness. Successfully estimating cartilage contact pressure using an EF model and these surfaces would efficiently generate data useful to studying the effects of hip pathologies without requiring CT arthrograms.