Biomedical Engineering and Bioengineering Commons^™

Biomechanical And Radiographic Evaluation Of An Ovine Model For The Human Lumbar Spine, Nina E. Easley, M. Wang, Linda M. Mcgrady, Jeffrey M. Toth

Biomedical Engineering Faculty Research and Publications

While various species of animal models have been used in preclinical investigations of spinal implant devices to assess their biological adaptation and biomechanical performance, few studies have made comprehensive comparisons to validate their suitability of modelling the human spine. The purpose of this study was to assess essential biomechanical behaviours and disc morphology of the ovine lumbar model. Flexibility testing was conducted on the spines (L3—L4 and L4—L5) of nine skeletally matured sheep. Segmental rotation and intradiscal pressure were measured and load sharing between the intervertebral disc and posterior elements were calculated on the basis of a simplified parallel spring …

Relationship Between Arch Height And Midfoot Joint Pressures During Gait, Dong Gil Lee

ETD Archive

A foot arch is a multi-segmented curved structure which acts as a spring during locomotion. It is well known that ligaments are important components contributing to this spring-like property of the arch. In addition, intrinsic and extrinsic foot muscles contribute to arch support. According to the windlass foot model, arch height and midfoot joint orientation change during gait. However, it is not known whether altered joint configurations result in increased joint stress during gait. If so, it is possible for there to be a "vicious cycle" in which joint stress increases as the arch height diminishes, which may then lead …

Spatial Sensors For Quantitative Assessment Of Retrieved Arthroplasty Bearings, Melinda Harman

All Dissertations

Evaluation of retrieved joint arthroplasty bearings provides unique evidence related to the physiological environment in which bearing materials are expected to perform. This dissertation describes the development of novel spatial sensors and measurement strategies for standardized, quantitative assessments of arthroplasty bearings, including total knee replacements, unicompartmental knee replacements, and total hip replacements. The approach is to assess bearings that endured a finite duration of function in patients, with particular emphasis on expanding our understanding of the biomechanical conditions specific to bearing function and wear in the physiological environment. Several quantifiable parameters are identified that prove comparable to pre-clinical in vitro …

The Use Of Hinged External Fixation To Provide Additional Stabilization For Fractures Of The Distal Humerus, Christopher R. Deuel, Philip Wolinsky, Eric Shepherd, Scott Hazelwood

Biomedical Engineering

Objective: To assess improvements in fixation stability when a hinged unilateral external fixator is used to supplement compromised internal fixation for distal humerus fractures.

Methods: Removing a 1-cm section of the distal humerus in cadaveric whole-arm specimens created a comminuted distal humerus fracture model (AO type 13-A3). Fixation was then performed using different constructs representing optimal, compromised, or supplemented internal fixation. Internal fixation consisted of either 2 reconstruction plates with 1, 2, or 3 (optimal) distal attachment screws, or crossing medial and lateral cortical screws. A hinged external fixator was applied in combination with compromised internal fixation. The stability of …

An Unsupervised Fluoroscopic Analysis Of Knee Joint Kinematics, Charles Scott, Elisa H. Barney Smith

Electrical and Computer Engineering Faculty Publications and Presentations

Knowledge of the three dimensional positions of bones at a joint as a function of time is required to accurately model joint kinematics. 3-D bone geometry data from a static computer tomography (CT) images can be combined with time sequence information from 2-D video fluoroscopy images to produce 3-D position data over time. The process involves creating virtual X-rays from the CT image through digitally reconstructed radiograph (DRR) projections. Historically, the process of matching the 3-D and 2-D data has required human interaction. We have eliminated the need for manual initialization using a Monte Carlo technique with a variable search …

A New Biomechanical Head Injury Criterion, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

This paper presents a new analysis of the physics of closed head injury caused by intense acceleration of the head. At rest a 1 cm gap filled with cerebrospinal fluid (CSF) separates the human brain from the skull. During impact whole head acceleration induces artificial gravity within the skull. Because its density differs slightly from that of CSF, the brain accelerates, strikes the inner aspect of the rigid skull, and undergoes viscoelastic deformation. Analytical methods for a lumped parameter model of the brain predict internal brain motions that correlate well with published high-speed photographic studies. The same methods predict a …

Brain Motion And Deformation During Closed Head Injury In The Presence Of Cerebrospinal Fluid, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

This paper presents a new analysis of the physics of closed head injury following brief, intense acceleration of the head. It focuses upon the buoyancy of the brain in cerebrospinal fluid, which protects against damage, the propagation of strain waves through the brain substance, which causes damage, and the concentration of strain in critical anatomic regions, which magnifies damage. Numerical methods are used to create animations or "movies" of brain motion and deformation. Initially a 1 cm gap filled with cerebrospinal fluid (CSF) separates the brain from the skull. Whole head acceleration induces artificial gravity within the skull. The brain …

Model And Clinical Device Development For Noninvasive Diagnosis Of Low Back Pain And Dysfunction, Ravi Patraju

Theses

Millions of people suffer from acute or chronic low back pain. In order for proper treatment to be administered, a patient must receive an accurate diagnosis. Therefore, it is critical to develop an objective model to measure the motion and any dysfunction of a patient's low back. Only then can a physician effectively implement the correct therapy and measure its effectiveness through follow-up to minimize or eliminate low back pain.

Numerous cadaveric, active and passive studies have been done to understand the mechanics of low back disorders. However, only living human subjects suffer from low back pain and therefore cadaveric …

The Morphology Of Uhmwpe Wear Debris Generated By A Hip Joint Simulator, Aaron P. Essner

Theses

The size, quantity and shape of total hip replacement wear debris may identify wear mechanisms as well as play a role in osteolysis. Characterization of wear particles generated from a hip joint simulator was conducted followed by comparison with literature reported in vivo results. The effect of counterface material and lubricant type on particle morphology was assessed. Biomaterial pairs including UHMWPE articulated against CoCr, Alumina and Zirconia were considered. Deionized (D.I.) water and bovine serum were used as lubricants. Particles generated from Alumina/UHMWPE in serum were slightly larger than those for CoCr and Zirconia against UHMWPE in serum. Particle shape …

The Articular Cartilage Of The Rabbit Knee: A Scanning Electron Microscopy Study, Daniel Levanon, Haim Stein

Cells and Materials

The surface morphology of eight sectors in the rabbit knee articular cartilage was studied using scanning electron microscopy. Cartilage surfaces showed wide variation in the shape, dimensions , and density of gaps and acellular processes. Patellas and load-bearing condyles revealed a relatively higher density of processes than did load-free condyles. Surface processes and gaps were abundant. They might represent a condensation product(s) of hyaluronic acid/protein complex that accrues during cycles of loading/weight bearing.

Optimization Of The Design Of The Harrington Distraction Rod And Hooks, Margaret Ann Pisani

Theses

The Harrington Distraction Rod is presently attached to the spines of patients who suffer from scoliosis and vertebral fractures. The rod's purpose is to apply a distractive force to the scoliotic curve in an attempt to reduce its severity. In fractures this rod is implanted to reduce the fracture and increase the stability of the spinal column. Harrington distraction rods are also inserted in order to give mechanical support to the spinal column.

Presently the Harrington Distraction Rod, manufactured by Zimmer, is one—quarter inch in diameter and made of 316L cold—worked stainless steel. The proximal end of the rod consists …