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Integration of a Finite Element Model with the DAP Bone Remodeling Model to Characterize Bone Response to Skeletal LoadingNASA's Digital Astronaut Project (DAP) has developed a bone remodeling model that has been validated for predicting volumetric bone mineral density (vBMD) changes of trabecular and cortical bone in the absence of mechanical loading. The model was recently updated to include skeletal loading from exercise and free living activities to maintain healthy bone using a new daily load stimulus (DLS). This new formula was developed based on an extensive review of existing DLS formulas, as discussed in the abstract by Pennline et al. The DLS formula incorporated into the bone remodeling model utilizes strains and stress calculated from finite element model (FEM) of the bone region of interest. The proximal femur was selected for the initial application of the DLS formula, with a specific focus on the femoral neck. METHODS: The FEM was generated from CAD geometry of a femur using de-identified CT data. The femur was meshed using linear tetrahedral elements Figure (1) with higher mesh densities in the femoral neck region, which is the primary region of interest for the initial application of the DLS formula in concert with the DAP bone remodeling model. Nodal loads were applied to the femoral head and the greater trochanter and the base of the femur was held fixed. An L2 norm study was conducted to reduce the length of the femoral shaft without significantly impacting the stresses in the femoral neck. The material properties of the FEM of the proximal femur were separated between cortical and trabecular regions to work with the bone remodeling model. Determining the elements with cortical material properties in the FEM was based off of publicly available CT hip scans [4] that were segmented, cleaned, and overlaid onto the FEM.
Document ID
Acquisition Source
Glenn Research Center
Document Type
Conference Paper
Werner, Christopher R.
(ZIN Technologies, Inc. Middleburg Heights, OH, United States)
Mulugeta, Lealem
(Universities Space Research Association Houston, TX, United States)
Myers, J. G.
(NASA Glenn Research Center Cleveland, OH, United States)
Pennline, J. A.
(NASA Glenn Research Center Cleveland, OH, United States)
Date Acquired
March 10, 2015
Publication Date
January 13, 2015
Subject Category
Life Sciences (General)
Report/Patent Number
Meeting Information
Meeting: Human Research Program Investigator''s Workshop
Location: Galveston, TX
Country: United States
Start Date: January 13, 2015
End Date: January 15, 2015
Sponsors: NASA Johnson Space Center, National Space Biomedical Research Inst.
Funding Number(s)
WBS: WBS 516724.01.02.10
Distribution Limits
Public Use Permitted.
Bone Remodeling
Mechanical Stimulus
Finite Element Model
Proximal Femur
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