Engineering Commons^™

Osteocyte Activity And Skeletal Muscle Relative Gene Expression Profiling After Short-Term Muscle Paralysis, Michelle Gelbs

Dissertations and Theses

Mechanical loading is essential for maintaining bone tissue. Reduced mechanical loading has been shown to have a negative effect on bone, and can result in the development of disuse osteoporosis. Disuse models of muscle inactivity and immobilization, like the Botox model used in this study, result in changes in the bone microarchitecture, the mechanisms behind which are not fully understood. In a previous four-week Botox disuse study, skeletally mature 20- week-old rats experienced degradation of intracortical bone, increased vascular porosity, and decreased osteocyte lacunar density in the tibiae. The focus of this study was to explicate a potential source of …

Diffuse Damage Repair Mechanism In Bone, Leila Mehraban Alvandi

Dissertations and Theses

Bone microdamage is a result of fatigue, creep or ‘wear and tear’ caused by physiological activities and largely contributes to bone fragility. Bone, unlike engineered materials, has the ability to repair the microscopic cracking or microdamage through targeted, osteoclast-mediated bone remodeling. This capability is crucial for preservation of its structural integrity and quality; failure of the skeleton to effectively repair microdamage leads to accumulation of damage, which is one of the main contributors to bone fragility. Linear microcracks (50-100 µm) and diffuse damage (Dif.Dx) (sub-micron) are the two types of microdamage. Recent studies show that Dif.Dx repairs without bone remodeling, …

Nanocellulose Fibers As A Potential Material For Orthopedic Implantation Application, David Gregg Holomakoff

Electronic Theses and Dissertations

The field of biomaterials is of immense importance and will continue to grow and develop in the coming years. Novel materials, as well as new approaches for use of existing materials, are sought after now more than ever. Current metal orthopedic implants have an over engineered stiffness and Young’s modulus, causing a phenomenon called stress shielding. Metal implants absorb the majority of force typically exerted on bone and the osteocytes within. When osteocytes fail to sense mechanical forces bones become less dense and weaken, causing possible fracture and other complications. A new orthopedic material is needed matching Young’s modulus of …

Multi-Scale Assessment Of Bone Mechanics And The Mineral Phase Of Intramuscular Bone Of Atlantic Herring Fish, Svetlana Zeveleva

Dissertations and Theses

Bone tissue is a complex composite structure made up of a soft organic phase consisting of collagen I and non-collagenous proteins, and a hard inorganic phase consisting of mineral nanoplatelets. Given it’s compositional properties, bone is a unique stiff, tough, and strong biomaterial, making it exceptionally difficult to synthesize ex vivo. While the complete hierarchical structure may change with age and population, the basic building block components of mineralized collagen fibrils, are preserved. This study uses a model of intramuscular bone of the Atlantic herring fish, which present a simple structure, and no process of remodeling.

A multi-scale approach …

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 …

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 …

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 …