Abstract:
Methods to predict contact stresses in the hip are crucial for a deeper understanding of load distribution in both healthy and diseased joints, particularly for addressing osteoarthritis (OA). The primary objectives of this biomechanical study were to develop and validate a three-dimensional finite element (FE) model specifically designed for predicting cartilage contact stresses in the human hip. This subject-specific FE model utilized geometry derived from computed tomography (CT) image data and also assessed the sensitivity of its predictions to various boundary conditions, cartilage geometry, and material properties. Experimental loads, based on in vivo data, were applied to a cadaveric hip joint to simulate daily activities such as walking, descending stairs, and stair-climbing, with contact pressures and areas measured using pressure-sensitive film. The FE meshes for bone and cartilage were meticulously segmented and discretized from CT image data. A critical step in this computational protocol involved importing acetabular and femoral cartilage surfaces into the FE preprocessing software, TrueGrid, where hexahedral element meshes were created, demonstrating TrueGrid's essential role in generating the detailed mesh required for accurate biomechanical simulations. The study achieved fair to good qualitative correspondence between FE predictions and experimental measurements for simulated walking and descending stairs, with excellent agreement observed for stair-climbing. While experimental peak pressures ranged up to 10.0 MPa, FE predictions were slightly higher, ranging from 10.8-12.7 MPa. Sensitivity analyses revealed that alterations to cartilage shear modulus, bulk modulus, or thickness resulted in approximately ±25% changes in peak pressures, emphasizing the importance of accurate material properties in biomechanical modeling. This validated biomechanical modeling framework establishes a strong foundation for the future development of patient-specific FE models, enabling deeper investigations into the mechanics of both normal and pathological human hips.
