Biomedical Engineering and Bioengineering Commons^™

Analysis, Segmentation And Prediction Of Knee Cartilage Using Statistical Shape Models, Joseph Michael Johnson

Doctoral Dissertations

Osteoarthritis (OA) of the knee is one of the leading causes of chronic disability (along with the hip). Due to rising healthcare costs associated with OA, it is important to fully understand the disease and how it progresses in the knee. One symptom of knee OA is the degeneration of cartilage in the articulating knee. The cartilage pad plays a major role in painting the biomechanical picture of the knee. This work attempts to quantify the cartilage thickness of healthy male and female knees using statistical shape models (SSMs) for a deep knee bend activity. Additionally, novel cartilage segmentation from …

Mechanical Properties Of Bone Due To Sost Expression: Nanoindentation Assessment Of Murine Femurs, Amir Rafie

Master's Theses

In the human genome, the SOST gene codes for a protein sclerostin. Sclerostin is an osteocyte-expressed negative regulator of bone formation. When the SOST gene is not coded, bone formation is reduced in individuals during skeletal maturation. This study utilizes nanoindentation methods to test for the mechanical properties of bones that both express and do not express the SOST gene. 100 transgenic murine femurs were obtained from Lawrence Livermore Labs in the form of 6 and 8 month SOST transgenic mice, 6 and 12 month SOST knockout mice, and wild type control littermates for each of the 4 age groups. …

Tooth Cusp Radius Of Curvature As A Dietary Correlate In Primates, Michael Anthony Berthaume

Open Access Dissertations

Tooth cusp radius of curvature (RoC) has been hypothesized to play an important role in food item breakdown, but has remained largely unstudied due to difficulties in measuring and modeling RoC in multicusped teeth. We tested these hypotheses using a parametric model of a four cusped, maxillary, bunodont molar in conjunction with finite element analysis. When our data failed to support existing hypotheses, we put forth and tested the Complex Cusp Hypothesis which states that, during brittle food items breakdown, an optimally shaped molar would be maximizing stresses in the food item while minimizing stresses in the enamel. After gaining …

The Effect Of Stem Surface Treatment And Substrate Material On Joint Replacement Stability: An In-Vitro Investigation Into The Stem-Cement Interface Mechanics Under Various Loading Modes, Yara K. Hosein

Electronic Thesis and Dissertation Repository

Mechanical loosening is a common mode of joint replacement failure. For cemented implants, loosening at the implant-cement interface may be affected by stem surface design. Altering the surface topography facilitates the infiltration of bone cement onto the stem, creating a mechanical interlock, improving interface stability. However, few in-vitro studies have investigated this. Therefore, the purpose of this thesis was to investigate the effect of stem surface treatments and substrate materials on stem-cement interface stability in-vitro.

Four separate studies were performed to assess the stability of various stem surface treatments, with two substrate materials, under three loading modes. Titanium and …

Discrete Geometric Based Stress Analysis Of The Lumbar Soft Tissues From In Vivo Kinematics, Joseph W. Mitchell

Doctoral Dissertations

Back pain in the region of the lumbar spine has become an increasingly significant problem among individuals in the United States and is a leading cause of disability and missed work days. At present, efforts focused on treating both the symptoms and causes of low back pain have proven to be difficult, and researchers and clinicians still do not fully understand the most effective means for treating the symptoms. Utilizing a biomechanics approach, it is assumed that lower back pain is, at least in part, associated with an increased localized stress.

Current models used to determine stresses are typically based …

Development Of A Computational Methodology For Evaluating In Vivo Vertebral Mechanics In Subjects Having Various Conditions Of The Lumbar Spine, Christopher Brian Carr

Doctoral Dissertations

Treating and evaluating the causes of low back pain (LBP) is difficult and not fully understood. However, assessing the in vivo motions and loading characteristics in the lumbar spine may provide important data for progressing the diagnosis and treatment of pathologies linked with LBP.

This dissertation describes the development of a comprehensive approach for collecting both the kinematics and kinetics of the lumbar vertebrae under in vivo conditions. Forty-four subjects representing healthy, symptomatic, pathological, and surgically implanted (pre- and post-operative) conditions of the lumbar spine were evaluated using dynamic fluoroscopy and 3D-to-2D image registration to assess the motions of the …

Finite Element Analysis And Validation Of Hip Joints With The Main Types Of Femoroacetabular Impingement, Kevin Lucas Mitchell

Master's Theses

Current research suggests that femoroacetabular impingement can be a cause of osteoarthritis. Femoroacetabular impingement is a condition that can affect both the femur and the pelvis of an individual. Femoroacetabular impingement can cause damage to the hip joint and its surrounding tissues. The articular cartilage and the labrum are both affected by this condition. A cam impingement is where a bony protrusion develops at the femoral head/neck junction. A pincer impingement is where a bony protrusion develops at the acetabular rim. Often, patients are seen with a combination of both impingements. The main goal of this study was to computationally …

The Effects Of Variation In Collagen D-Spacing On Compact Bone Viscoelasticity: A Finite Element Analysis, Miguel A. Mendoza

Master's Theses

The D-spacing that is characteristic of collagen and its structural arrangement was previously thought to be a constant value. Much research is revealing that it is actually a distribution of values in biological tissues. Recent ovine experimentation has also shown that the D-spacing distribution is significantly altered following estrogen depletion. While ewes contain some major biological differences between their human counterparts, they are an economical and robust large animal model for postmenopausal osteoporosis. So, the exploration of the possible implications that D-spacing has on the mechanical properties of the whole bone utilizing animal models and computational methods is warranted. Six …

Computational Biomechanical Modeling Of The Human Knee During Kneeling, Tariq R. Abo-Alhol

Electronic Theses and Dissertations

Total knee replacement benefits patients who suffer from severe knee pain or joint stiffness and other joint related illnesses that limit everyday activities. There has been an increase in the number of procedures performed each year and a need to evaluate the performance of these implants during specialized activities such as kneeling. Most computational studies lack insight into inter-patient variability and the results do not apply to large population. This study developed: (1) three-dimensional explicit finite element (FE) models to investigate natural and implanted knee joint kinematics and bone strain and (2) a platform to enable population-based evaluation by combining …

Subtalar Joint Instability: Diagnosis And Conservative Treatment, Julie Choisne

Mechanical & Aerospace Engineering Theses & Dissertations

Subtalar instability may be caused by various ligamentous injuries. Combined instability at the ankle and subtalar joint is not adequately diagnosed. Further, isolated subtalar instability is usually misdiagnosed which may lead to long term damage to the joint. Developing a non-invasive and clinically practical tool to diagnose subtalar joint instability would be an important asset. The ability of an ankle brace, a common treatment for hindfoot instability, to promote stability for the subtalar joint was not well established. The purposes of this study were to 1) assess the kinematics of the subtalar, ankle, and hindfoot in the presence of isolated …

Evaluation Of The Anterior Talofibular And Calcaneofibular Ligament In Relation To Supination Ankle Sprains, Peter Tran

Biomedical Engineering

Ankle injuries have always posed an issue to a number of athletes. Sports that involve running and jumping accumulate about 25% of injuries correlating to ankle sprains. In most ankle sprains the inversion (supination) of the ankle cause damage to lateral ligaments. The two most common lateral ligaments to experience damage are the anterior talofibular (ATFL) and calcaneofibular (CFL) ligaments. The methods of taping and ankle braces have allowed athletes to prevent recurring sprains from occurring. However, sprains can still occur even when one or both methods are applied. The purpose of each method is to restrict the range of …

Analysis Of Acetabular Cup Orientation Effects On Stress Shielding In Total Hip Replacements Using Finite Element Methods, Brogan Mcguire, Jennifer Gemkow, Brad Gausewitz, Alex Georges

Biomedical Engineering

Improper positioning of the acetabular cup has been shown to contribute to issues such as high wear rates and dislocations in total hip replacements. The differences in contact mechanics due to varying orientation of the acetabular cup may also significantly affect strain distribution in the femur. This study examined these effects of acetabular orientation changes and their contribution to stress shielding using finite element analysis. A solid model of a cementless total hip implant was obtained using 3D point scanning and implanted virtually into a femur solid model. The implanted femur model was imported into ABAQUS and loaded with a …

Design And Development Of A Stair Ascension Assistive Device For Transfemoral Amputees, Casey Michael Barbarino

Master's Theses

Transfemoral amputees around the world experience increased difficulty in climbing stairs due to lack of muscle, balance, and other factors. The loss of a lower limb greatly diminishes the amount of natural force generation provided that is necessary to propel oneself up stairs. This study investigated possible solutions to the problem of stair ascension for transfemoral amputees by the means of designing and developing an externally attachable device to a prosthesis. The number of amputations from military service has greatly increased since 2008, which shows there is a clear need for assistive devices (Wenke, Krueger, & Ficke, 2012). With the …

Universal Personal Transfer, Arian Nasab

Chancellor’s Honors Program Projects

No abstract provided.

Modeling The Zimmer Fitmore And Ml Taper Implantation, Tyler Kazuo Franklin

Master's Theses

With more young adults requiring total hip

arthroplasties the need for bone saving implants becomes

more important. The Zimmer Fitmore is a new bone saving

implant that utilizes an implantation technique that

reduces the damage to the muscle tissue allowing for

patients to have a short recovery time as well as a new

design that allows it to rest on the medial cortex. There

has been anecdotal evidence that this device leads to early

revision within six months of implantation due to failures

occurring in the medial cortex. The main goal of this

study was to computationally model the Zimmer …

A Microfluidic Pretreatment Isoelectric Focusing Dc-Field Assisted H-Filter For The Separation Of Charged Particles, Cameron Sean Carroll

Biomedical Engineering

Microfluidic devices are small portable diagnostic chips that allow for analysis of a biologic sample at relatively low cost. This makes them ideal for settings where a hospital is unavailable. The microfluidic pretreatment isoelectric focusing DC-field assisted H-filter is a device that allows for the separation of differently charged particles in a biologic sample. It does this by employing the concepts of diffusion, electrophoresis, and isoelectric focusing. This is perfect for isolation of a desired analyte or separation of waste from a sample in order to achieve better diagnostic results. The device was first modeled mathematically and visually using Comsol. …

Effect Of Rolling On Viscoelastic Fluids Using A Novel Testing Device, Aswini Mangadu

Dissertations and Theses

The purpose of this research thesis project was to develop a mechanical testing device that could enable us to load articular cartilage with a rolling/sliding motion. This novel device was then used to observe the effect of a rolling motion on the fluid film thickness of different lubricants (motor oil, synovial fluid and Hyaluronic Acid (HA)) to varying loads (1kg, 2,kg, 3kg and 4kg) and speeds (10, 25, 48 and 91 mm/s) applied on the sample fluids for 10 cycles. We were able to examine the effect of different speeds within each load for each of the fluid that was …

The Effects Of Hydrostatic Pressure On Early Endothelial Tubulogenic Processes, Ryan M. Underwood

Theses and Dissertations--Biomedical Engineering

The effects of mechanical forces on endothelial cell function and behavior are well documented, but have not been fully characterized. Specifically, fluid pressure has been shown to elicit physical and chemical responses known to be involved in the initiation and progression of endothelial cell-mediated vascularization. Central to the process of vascularization is the formation of tube-like structures. This process—tubulogenesis—is essential to both the physiological and pathological growth of tissues. Given the known effects of pressure on endothelial cells and its ubiquitous presence in the vasculature, we investigated pressure as a magnitude-dependent parameter for the regulation of endothelial tubulogenic activity. To …