Biological Engineering Commons^™

Reproducibility In Modeling Of Knee Joint Mechanics, Maryam Nazem

Electronic Theses and Dissertations

Computational modeling of knee joint biomechanics can provide valuable insights into joint function, injury mechanisms, and patient outcomes, and can support surgical planning and informed clinical decision-making. However, achieving consistent and repeatable results, or reproducibility, is a significant challenge that affects the credibility of these models. This thesis addresses reproducibility through two studies related to the KneeHub Project, which is a multi-institutional collaboration designed to investigate reproducibility in finite-element modeling of the knee.

The first study involved model benchmarking, where predicted results of the calibrated models were compared with the experimental data to evaluate model reproducibility. While all models replicated …

Influence Of Obesity On Knee Joint Mechanics: A Subject-Specific Musculoskeletal Modeling Approach, Ryan C. Knowles

Electronic Theses and Dissertations

Obesity has been consistently linked to knee osteoarthritis (KOA), a debilitating joint disease. While prior work has shown that obese individuals often walk with altered biomechanics compared to normal-weight (NW) individuals, which may accelerate KOA progression, less is known about how these mechanics affect load distribution between the medial and lateral tibiofemoral (TF) compartments, particularly during higher-demand activities. This study developed subject-specific musculoskeletal models of five obese and five NW individuals, incorporating CT-based bone measurements and individualized joint contact points. Simulations were driven by six degree-of-freedom (6DOF) kinematics obtained from high-speed stereo radiography (HSSR) to predict TF loading and associated …

Computational Fluid Dynamics And Fluid Structure Interaction Modeling In Healthy Vertebral Arteries: A Comparative Study, Bryce Clinkenbeard

Electronic Theses and Dissertations

Cerebral perfusion is critical for maintaining proper brain function, with each cerebrovascular artery playing an integral role in the overall cerebrovascular system. When these arteries become damaged or develop plaque, cardiovascular disease (CVDs) such as atherosclerosis can arise, leading to conditions like arterial stenosis. While CVDs are most prevalent in older individuals, they are also observed in young adults, particularly those engaged in high-endurance occupations such as military service. Diagnosis and prediction of CVDs often rely on imaging modalities supported by computational fluid dynamics (CFD) which account for low resolution in fluid flow. CFD models assume rigid arterial walls, which …

The Impact Of Cumulative And Acute Loading On Achilles Tendon Health, Performance, And Reported Pain In Collegiate Gymnasts, Julio Serrano Samayoa

Electronic Theses and Dissertations

Gymnasts are at a high risk of Achilles tendon (AT) injuries due to intense loads during takeoffs and landings. To better understand better the relationship between impact loading and its effects on tendon adaptation and athletic performance, this study uses Inertial Measurement Units (IMUs) to track AT loading across a collegiate gymnastics season. This data were compared against physiological and athletic performance metrics, obtained through force plates and ultrasound imaging, to explore how mechanical load influences reported pain and athletic performance. Results varied, with cumulative impacts being correlated with improved jump height (Spearman 0.362, Pearson 0.348), while peak power and …

Statistical Modeling Of Knee Morphology And Material Properties Considering Diverse Populations, Gabrielle Jeannine Kindy

Electronic Theses and Dissertations

Total Knee Arthroplasty (TKA) is a widely performed surgical procedure aimed at alleviating pain and restoring function in patients with severe knee osteoarthritis. Despite its general success, disparities in postoperative outcomes have been observed across different racial and ethnic groups, with minority populations often experiencing less favorable results. One potential avenue for improving the generalizability of orthopaedic implants is using Statistical Shape and Intensity Models (SSIMs), which can be used to incorporate patient variability directly into the orthopaedic medical device development workflow through population-based finite element analysis.

This work aimed to construct an SSIM from a diverse subject set, incorporating …

Improving Quantification Of Mitral Regurgitation Through Computational Fluid Dynamics And Ex Vivo Testing, Alexandra Flowers

Electronic Theses and Dissertations

Mitral regurgitation (MR) is a prominent cardiac disease affecting more than two million people in the United States alone. In order for patients to receive proper therapy, regurgitant volume must first be quantified. As there are an array of methods to do so, the proximal isovelocity surface area (PISA) method continues to be the most accurate and clinically used method. However, there are some difficulties obtaining the necessary measurements need for this when performing transthoracic echocardiography. This study aims to evaluate and present techniques that may be used to more accurately quantify regurgitation through ex vivo testing and computational fluid …

Pulmonary Valve Replacement, Mina Shafiei

Electronic Theses and Dissertations

Currently, transcatheter pulmonary valve replacement (TPVR) is a well-established alternative for surgical pulmonary valve replacement (SPVR) to treat pulmonary valve disorders in patients with prior congenital heart surgery. Edwards Sapien 3 valve is a bioprosthesis originally designed for the aortic position but has been used off-label in native right ventricular outflow tract (RVOT). It is currently under clinical trial to get food and drug administration (FDA) approval.

This study is a comparison of the performance of Sapien 3 with surgical bioprosthetics. The in vitro tests result showed Sapien 3 experiences less degree of opening and effective orifice area in pulmonic …

Revision Total Hip Femoral Stem Micromotion And Statistical Shape Modeling Of The Knee, William Fugit

Electronic Theses and Dissertations

The first purpose of this thesis was to compare the amount of micromotion seen in the femoral stem in a revision total hip arthroplasty between simple loading conditions and loading conditions derived from activities of daily living, through the use of experimental and computational methods. The amount of micromotion at the bone-implant interface was larger for activities of daily living, with ranges of 200μm more than the largest simple loading conditions. The second purpose of this thesis was to compare measurements of accuracy in a statistical shape model between individual bone and joint-level models, specifically for the knee. Using computational …

Correlating With Local Variation In Collagen Level And Mechanical Properties Of The Heart Tissues, Talayeh Tavangar

Electronic Theses and Dissertations

The determination of the myocardium's tissue properties is essential in constructing finite element (FE) models of the heart. To obtain accurate results, especially for functionally modeling the heart, we must determine the tissue properties in-vivo. The calculation of the heart tissue properties remains a challenging area as it is categorized as a heterogeneous, anisotropic, nonlinear soft tissue that undergoes large deformation. In this work, we tried to introduce and evaluated a finite element method to determine the mechanical properties of the cardiac tissue. The introduced method combined a finite element modeling with the experimentally obtained images from the left and …

Tibial Strains And Tray-Bone Micromotions After Total Knee Arthroplasty: Computational Studies Evaluating The Tibial Fixation, Huizhou Yang

Electronic Theses and Dissertations

Cemented and cementless fixation in total knee arthroplasty (TKA) have been successfully used for decades. As the number of younger and more active patients treated with TKA continues to increase, long-term implant survivorship is of increasing importance. One of the most common complications and hence the reason for revision is mechanical loosening (23.1% of all revised TKA). The loosening mechanisms have been proposed for different fixation types. For cemented fixation, bone remodeling after surgery is regulated by the changes in strain energy density (SED). The recruitment of osteoclasts and osteoblasts is controlled by SED-related signals. Insufficient stimuli can promote bone …

Fluid Dynamics Characterization Of Transcatheter Aortic Valves, Mohammed Barakat

Electronic Theses and Dissertations

Aortic stenosis due to degenerative calcific aortic valvular disease is the most reason for aortic valve replacement in developed countries. Aortic stenosis affects up to 7% of the world population, and current clinical data indicate that the number of the affected people could be triple by 2050, due to population ageing and health lifestyle. Transcatheter aortic valve replacement (TAVR) was introduced as a minimal invasive treatment of severe aortic stenosis. Even though surgical aortic valve replacement (SAVR) is considered the golden standard treatment for severe aortic stenosis patients, TAVR showed equivalent or even superior outcome compare to SAVR. Currently, transcatheter …

Mechanical Effects Of Surgical Adhesives On Ascending Thoracic Aortic Aneurysm Replacement, Dong Qiu

Electronic Theses and Dissertations

Ascending thoracic aortic aneurysm (aTAA) is a potentially lethal disease which grows gradually over time and may lead to aortic dissection and rupture. Currently, aTAA surgical repair using Dacron graft is a well-established treatment. In addition, surgical adhesives are frequently used in the surgeries to seal the anastomotic site. This study aims to investigate mechanical effects of four commonly used surgical adhesives, namely BioGlue, CoSeal, Crosseal, and Tisseel, on the suture site using in-vitro digital image correlation (DIC) method and finite element (FE) simulations in an ovine model. In this study, first, mechanical properties of ovine ascending aorta were obtained …

Development Of A Computational Approach To Assess Hip Fracture And Repair: Considerations Of Intersubject And Surgical Alignment Variability, Azhar Ali

Electronic Theses and Dissertations

Hip fracture remains a major public health concern due to the significant number of occurrences and mortality rates. Intertrochanteric fractures are the most common type of fracture and are typically caused by a fall. Intramedullary osteosynthesis is a common surgical practice to repair intertrochanteric fractures, but revisions are often required. The work presented in this thesis aims to improve the realism and fidelity of computational models of hip fracture, which can be an effective alternative to costly and labor-intensive clinical in-vivo and experimental in-vitro testing. Intersubject variability is inherently present in anatomy and material relations. Statistical shape and intensity models …