Session: 17-01-01: Research Posters

Paper Number: 150716

150716 - Development of a High-Fidelity Cad Model of the Female Foot Using Computed Tomography Data 

Overview  

A high-fidelity computer-aided design (CAD) model of the female foot was developed using computed tomography (CT) data acquired from the National Institutes of Health (NIH). Segmentation techniques were applied to create stereolithography models of each bone and the soft tissue. These models underwent cleaning and further refinement to produce Non-Uniform Rational B-Spline (NURBS) surfaces and final CAD models. 

Background 

Existing studies underscore the importance of accurate foot models for biomechanical analysis. Hodge et al. (1999) highlighted the role of orthotic management in reducing plantar pressure and pain, while Raspovic et al. (2000) emphasized the impact of customized insoles on diabetic foot ulcers. Cavanagh and Rodgers (1987) provided foundational insights into pressure distributions under healthy feet, and Knapp (2001) developed 3D geometry of the male foot for finite element plantar fasciitis studies. Benjamin et al. (2006) highlighted the significance of detailed anatomical models for assessing internal structures under various loading conditions. 

Building on these foundational studies, our project aims to deliver a robust CAD model that will facilitate future biomechanical simulations and enhance understanding of foot mechanics. This refined modeling approach sets the groundwork for analyses that could improve clinical outcomes for foot-related ailments. 

CT Data Segmentation 

The process of data segmentation involved isolating the soft tissue from the bones and segmenting each bone through edits in both 2D and 3D. Initial segmentation consisted of an automated process in which Hounsfield threshold values of 226 HU to 1808 HU were used for the generation of the bone and –231 HU to 225 HU for the generation of soft tissue. Manual procedures followed, including filling cavities and holes, removing artifacts, and addressing issues that could disrupt finite element modeling (FEM). In the scans, the middle, ring, and little toes were pressing against each other and were combined in the soft tissue model. Separate models of their phalanges (3 through 5) were developed to ensure each bone was distinctly represented.  

CAD Model Generation and Refinement 

After segmentation, the models underwent a thorough cleaning process using Wrap by Geomagic. This involved smoothing the surfaces, filling small holes, and defeaturing noise or details too fine for future finite element analysis. Patches were developed to prepare the models for conversion into Non-Uniform Rational B-Spline (NURBS) surfaces. These NURBS surfaces provided a precise and smooth representation of the anatomical structures, which were then used to create the final CAD models.  

Future Work 

The high-fidelity CAD models of the female foot will be used for finite element analysis to predict stresses, deformations, and strains due to various loading conditions.  

 

References 

Hodge, M. C., Bach, T. M., & Carter, G. M. (1999). Orthotic management of plantar pressure and pain in rheumatoid arthritis. Clinical Biomechanics, 14(8), 567-575. ISSN 0268-0033. https://doi.org/10.1016/S0268-0033(99)00034-0. 

Raspovic, A., Newcombe, L., Lloyd, J., & Dalton, E. (2000). Effect of customized insoles on vertical plantar pressures in sites of previous neuropathic ulceration in the diabetic foot. The Foot, 10(3), 133-138. ISSN 0958-2592. https://doi.org/10.1054/foot.2000.0604. 

Cavanagh, P. R., Rodgers, M. M., & Iiboshi, A. (1987). Pressure distribution under symptom-free feet during barefoot standing. Foot & Ankle, 7(5), 262-276. https://doi.org/10.1177/107110078700700502 

Knapp, A., Schönning, A., Stagon, S., & Livingston, B. (2016). Development of 3D Geometry of the Foot for FE Plantar Fasciitis Study. The Journal of Management and Engineering Integration, Winter 2016 Volume. 

Benjamin, M., Toumi, H., Ralphs, J. R., Bydder, G., Best, T. M., & Milz, S. (2006). Where tendons and ligaments meet bone: attachment sites ('entheses') in relation to exercise and/or mechanical load. Journal of Anatomy, 208(4), 471-490. https://doi.org/10.1111/j.1469-7580.2006.00540.x. 

National Institutes of Health. (n.d.). Index of public/Visible-Human/Female-Images/radiological/normalCT/. Retrieved from c_vm2472.fro to c_vm2852.fro. 

Presenting Author: Carlos Hernandez Ortiz University of North Florida

Presenting Author Biography: Carlos Andres Hernandez Ortiz has a Bachelor of Science in Mechanical Engineering from the University of North Florida. He is continuing his studies to achieve a Master's Degree in Mechanical Engineering and is looking forward to discovering new studies of the foot.

Authors:

Carlos Hernandez Ortiz University of North Florida
Muhammad Mahdi Nabi University of North Florida
Alexandra Schonning University of North Florida
Jutima Simsiriwong University of North Florida