Biomechanics and Biotransport Commons^™

A Finite Element Analysis On The Viscoelasticity Of Postmenopausal Compact Bone Utilizing A Complex Collagen D-Spacing Model, Austin C. Cummings

Master's Theses

The nanoscale dimension known as D-spacing describes the staggering of collagen molecules, which are fundamental to the biphasic makeup of bone tissue. This dimension was long assumed to be constant, but recent studies have shown that the periodicity of collagen is variable. Given that the arrangement of collagen molecules is closely related to the degree of bone mineralization, recent studies have begun to look at D-spacing as a potential factor in the ongoing effort to battle postmenopausal osteoporosis. The theoretical models presented by previous studies have only opted to model a single collagen-hydroxyapatite period, so the creation of an intricate …

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. …

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 …

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 …

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 …

Viscoelastic Anisotropic Finite Element Mixture Model Of Articular Cartilage Using Viscoelastic Collagen Fibers And Validation With Stress Relaxation Data, Matthew Alexander Griebel

Master's Theses

Experimental results show that collagen fibers exhibit stress relaxation under tension and a highly anisotropic distribution. To further develop the earlier model of Stender [1], the collagen constituent was updated to reflect its intrinsic viscoelasticity and anisotropic distribution, and integrated with an existing mixture model with glycosaminoglycans and ground substance matrix. A two-term Prony series expansion of the quasi-linear viscoelastic model was chosen to model the viscoelastic properties of the collagen fibers. Material parameters were determined by using the simplex method to minimize the sum of squared errors between model results and experimental stress relaxation data of tissue in tension. …

A Kinetic Study Of Anti-Vegf-A Polyclonal Antibodies And Anti-Vegf-A Ssdna Aptamers, Heather A. Hedeen

Master's Theses

A new detection reagent that could possibly augment or replace antibodies research and diagnosis methods are aptamers. Aptamers are ssDNA, RNA or polypeptide constructs that function like active antibodies. Antibodies and aptamers both specifically bind to selected target molecules, and as such they enable the detection or targeting of the presence or absence of a specific antigen.

In order to ensure that ssDNA aptamers perform similarly to antibodies, anti-VEGF-A polyclonal antibody and anti-VEGF-A ssDNA aptamer were evaluated against vascular endothelial growth factor A (VEGF-A) using Surface Plasmon Resonance (SPR). It was hypothesized that the anti-VEGF-A aptamer had the same, if …

Development And Application Of A Portable System To Reliably Measure Grip Forces Using Thin-Film Force Sensors, Shane Vincent Tornifoglio

Master's Theses

Accurate tracking of hand grip force is an important consideration needed for a robust understanding in the study of human biomechanics. One aspect where it proves useful is in hand-arm vibration, such as from gripping a power tool. Depending on how firmly the user is gripping the tool, they may change their exposure levels to the tool vibration, which can lead to potential disorders such as Hand-Arm Vibration Syndrome (HAVS).

A small, battery powered portable force unit has been developed to supply power to, and condition, the signals from eight thin-film force sensors. This gives a better understanding of the …

A Comprehensive Methodology For Assessing Biomechanical Risks Associated With Hand Tool Use: Applied To Laparoscopic Surgical Instruments, Drew R. Seils

Master's Theses

Biomechanical risk factors are physical stressors that act on the neuromuscular structures of the human body and are present in all occupational settings. Repetition and intensity of tasks performed can magnify the effects of the biomechanical risks that a worker is exposed to.

After reviewing the current literature on ergonomics in laparoscopic surgery it was clear that a comprehensive approach to quantitatively reporting on the biomechanical risk factors associated with surgical hand tools had never been performed. Utilizing an opto-electronic motion capture system meant the exact surgeon posture was recorded during simulated surgical tasks. Electromyography was used to evaluate muscle …

Mechanical Properties Of Bone Due To Sost Expression: A 3-Point Bending Assessment Of Murine Femurs, Kainoa John Peterson

Master's Theses

Sclerostin, a protein coded for by the SOST gene, is an osteocyte-expressed negative regulator of bone formation. The absence of SOST in the genome may have an effect on bone formation both during skeletal maturation and full maturity. This study attempts to determine significant differences in the mechanical properties of bone that expresses SOST compared to bone that does not. One hundred femur samples from 6, 8, and 12 month old mice were obtained from Lawrence Livermore National Labs and loaded until failure using three-point bending. Results showed significant differences in treatment group effects for cross sectional area, yield force, …

Automation Of Orthodontic Wire Tester For Performing Three Point Bending Tests, Adithya Venkatesan

Master's Theses

Abstract

Understanding the biomechanical factors in orthodontics is important in order to improve the overall effectiveness of actual clinical treatment. An accurate method to study the threedimensional (3D) force systems and the resulting movements of teeth during orthodontic treatment is needed along with the understanding of the material properties of any orthodontic wire. Until recently, most of the orthodontic biomechanics literature was limited to twodimensional experimental studies. Recent advances in threedimensional computer modeling have also been developed but have been limited to the manual control of tooth movement. Overall, there is very little published evidence in the literature on the …

Effect Of Prostaglandin E2 On Mechanical Stresses Applied By Mc3t3-E1 Osteoblast-Like Cells On A Soft Hydrogel Substrate, Abhijit Deb Roy

Master's Theses

Osteoblasts are sensitive to mechanical stimuli and release Prostaglandin E2 (PGE2) when exposed to a fluid shear stress. The exact mechanism by which these cells sense mechanical stress is not well established. A study of the stresses applied by the osteoblasts, under the influence of PGE2, on a hydrogel provided information regarding intercellular-communication via changes in the substrate surface pattern.

A digital image correlation program was developed using the Levenberg-Marquardt optimization algorithm to analyze images and compare the deformations between pairs of images. Comparisons of images before and after the addition of PE2 to the media showed differences in the …

Finite Element Analysis Of The Effect Of Low-Speed Rear End Collisions On The Medial Meniscus, Daniel J. Tichon

Master's Theses

Low-speed, rear end vehicle collisions can inflict soft tissue damage to the passenger’s knees, especially the medial meniscus, which has been previously unexplained in published literature.  It is difficult to determine if factors such as age or other injury was the primary cause of the injury or if the accident acutely caused the meniscal tear.  Rear end collisions may produce a combination of compressive loading and torque about the knee that will injure the medial meniscus during the initial impact and the rebound phase.  The purpose of this study is to determine if it is possible for rear end low-speed …

The Use Of Motion Analysis Technology As An Alternative Means Of Assessing Spinal Deformity In Patients With Adolescent Idiopathic Scoliosis, Matthew J. Solomito

Master's Theses

Adolescent Idiopathic Scoliosis (AIS) is a three dimensional deformity of the spine that causes abnormal curvatures in the coronal and sagittal planes and abnormal vertebral rotations. The gold standard for diagnosing and tracking the progression of the deformity is through the use of repeated radiography and a patient can receive upwards of fifteen radiographic series over the course of treatment, which exposes this population to an increased risk of radiation-dependent complications.

This thesis presents the necessary calculations and the marker set required to make the motion capture technology a viable alternative to radiographs, in an effort to reduce the patient’s …

Integration Of Microfluidics With Surface Plasmon Resonance, Scott B. Fratzke

Master's Theses

This thesis successfully integrates laminate microfluidic devices with an analytic Surface Plasmon Resonance (SPR) instrument. Integration was accomplished at low-cost using materials such as polydimethylsiloxane (PDMS), Poly(methyl methacrylate) (PMMA), Tygon tubing, and a 3-way stopcock. The main components of this thesis are the design and fabrication of the low-cost, in-house fluidics that can integrate with upstream microfluidics and the validation of the in-house fluidics using the Biosensing Instruments BI-2000 SPR instrument. The low-cost fluidics was designed and fabricated “in-house” using a novel investment casting technique that required the use of laser cutting technology to make a master cast, and candle …

Modeling The Long Term Effects Of Alendronate On Bone Mass Preservation Of The Femur With Articular Surface And Total Hip Replacements, Trevor J. Hryce

Master's Theses

Calculating femoral bone density changes after hip arthroplasty is of interest to researchers and clinicians for predicting the longevity of the prosthetic implant and the surrounding bone. Recently clinicians have been administering bisphosphonate drugs in an attempt to reduce the bone resorption due to stress shielding caused by these implants. Current strain-adaptive computational models with bisphosphonate treatment don’t predict the long term effects or look at treatment with hip resurfacing implants. The main goal of this study was to create and validate a computer model of the human femur incorporating a bone remodeling algorithm based on biological remodeling processes and …

An Investigation Of Humeral Stress Fractures In Racing Thoroughbreds Using A 3d Finite Element Model In Conjunction With A Bone Remodeling Algorithm, Ryan James Moore

Master's Theses

The humerus of a racing horse Thoroughbred is highly susceptible to stress fractures at a characteristic location as a result of cyclic loading. The propensity of a Thoroughbred to exhibit humeral fracture has made equines useful models in the epidemiology of stress fractures. In this study, a racing Thoroughbred humerus was simulated during training using a 3D finite element model in conjunction with a bone remodeling algorithm. Nine muscle forces and two contact forces were applied to the 3-dimensional finite element model, which contains four separate load cases representing fore-stance, mid-stance, aft-stance, and standing. Four different training programs were incorporated …

Mechanical Simulation Of Articular Cartilage Based On Experimental Results, Kevin Matthew Stewart

Master's Theses

Recently, a constituent based cartilage growth finite element model (CGFEM) was developed in order to predict articular cartilage (AC) biomechanical properties before and after growth. Previous research has noted limitations in the CGFEM such as model convergence with growth periods greater than 12 days. The main aims of this work were to address these limitations through (1) implementation of an exact material Jacobian matrix definition using the Jaumann-Kirchhoff (J-K) method and (2) quantification of elastic material parameters based upon research findings of the Cal Poly Cartilage Biomechanics Group (CPGBG). The J-K method was successfully implemented into the CGFEM and exceeded …