Validation of Finite Element Predictions of Cartilage Contact Pressure in the Human Hip Joint

Abstract

Methods to predict contact stresses in the hip can provide an improved understanding of load distribution in the normal and pathologic joint. The objectives of this study were to develop and validate a three-dimensional finite element (FE) model for predicting cartilage contact stresses in the human hip using subject-specific geometry from computed tomography image data, and to assess the sensitivity of model predictions to boundary conditions, cartilage geometry, and cartilage material properties. Loads based on in vivo data were applied to a cadaveric hip joint to simulate walking, descending stairs and stair-climbing. Contact pressures and areas were measured using pressure sensitive film. CT image data were segmented and discretized into FE meshes of bone and cartilage. FE boundary and loading conditions mimicked the experimental testing. Fair to good qualitative correspondence was obtained between FE predictions and experimental measurements for simulated walking and descending stairs, while excellent agreement was obtained for stair-climbing. Experimental peak pressures, average pressures, and contact areas were 10.0 MPa (limit of film detection), 4.4-5.0 MPa and 321.9-425.1 mm 2 , respectively, while FE predicted peak pressures, average pressures and contact areas were 10.8-12.7 MPa, 5.1-6.2 MPa and 304.2-366.1 mm 2 , respectively. Misalignment errors, determined as the difference in root mean squared error before and after alignment of FE results, were less than 10%. Magnitude errors, determined as the residual error following alignment, were approximately 30% but decreased to 10-15% when the regions of highest pressure were compared. Alterations to the cartilage shear modulus, bulk modulus, or thickness resulted in ±25% change in peak pressures, while changes in average pressures and contact areas were minor (±10%). When the pelvis and proximal femur were represented as rigid, there were large changes, but the effect depended on the particular loading scenario. Overall, the subject-specific FE predictions compared favorably with pressure film measurements and were in good agreement with published experimental data. The validated modeling framework provides a foundation for development of patient-specific FE models to investigate the mechanics of normal and pathological hips.

Early Experience With a Comprehensive Hip Preservation Service Intended to Improve Clinical Care, Education, and Academic Productivity

“…An established clinical and basic science research relationship focusing on the principles of computational and experimental engineering mechanics, motion analysis, and imaging to solve unique problems related to hip pathomorphology was similarly improved [2,3,15,27]. We observed an increase in research activity, including an increase in peer-reviewed publications, projects in progress, and funded research grants, in the 3 years after creation of the HPS.…”

Changes in the stress in the femoral head neck junction after osteochondroplasty for hip impingement: A finite element study

“…These tissues were assumed to exhibit elastic-plastic, isotropic material behavior with properties taken from the literature [28][29][30][31][32] (Table 1). Full bonding was assumed at the interface between cortical and the cancellous bone.…”

Using a Finite Element Pediatric Hip Model in Clinical Evaluation - A Feasibility Study

“…This is caused by stress wave propagation in the explicit analyses, but is judged not to influence the overall response. Anderson et al combined an experimental and a computational study to validate a FE model of the hip joint with respect to cartilage contact pressure and contact area [7]. Their cartilage consisted of two geometrical layers with varying thickness.…”

“…Instead several three-dimensional finite element (FE) models have been constructed to evaluate the biomechanics of the mature human pelvis and hip joint. Some studies combined experimental trials with FE analyses in order to validate the stress distribution in the pelvic cortical bone or contact forces in the articular cartilage of FE models [5][6][7]. Harris et al constructed FE models of 10 hips and found large variations among subjects when considering contact forces in the articular cartilage [8].…”