The Impact Of Combined Flexion And Compression On The Mechanical Integrity Of The Annulus Fibrosus, Keaton Briar

Theses and Dissertations (Comprehensive)

Introduction: Intervertebral disc (IVD) herniation is characterized by an expulsion of nucleus pulposus (NP) material through the annulus fibrosus (AF). The AF contains two major adhesive structures, the intralamellar matrix and the interlamellar matrix, which act to maintain the strength of the AF and prevent NP material migration. As a herniation occurs, clefts form within the intralamellar matrix, pushing the NP between adjacent collagen fibres; meanwhile, delamination of the interlamellar matrix causes the NP to pool between layers of the AF. Further, herniation more readily occurs in a combined loading scenario of both compression and flexion. Flexion, and in particular …

Spinal Motor Neuron Excitability And Balance Control Changes Following Downslope Walking, Nikki Aitcheson-Huehn

Theses and Dissertations (Comprehensive)

Downslope walking (DSW) has been proposed as a rehabilitation tool for people with Multiple Sclerosis (PwMS) although there are mixed findings in young adults (YA) regarding the balance control changes, despite both populations experiencing depressed spinal motor neuron (MN) pool excitability. Our aim was to determine whether YAs could demonstrate improved balance control in conjunction with SOL H reflex depression (estimate of spinal MN excitability) following DSW. We also aimed to determine whether reciprocal inhibition was a potential mechanism for H reflex depression via conditioned SOL H reflexes. Thirty young adults (23±1.4y, 6 males) were assigned to 30-minutes of DSW …

Toll-Like Receptor 4 Inhibition Differentially Impacts Intervertebral Disc Axial Mechanics In Wild Type And Sparc-Null Mice, Mitch Whittal

Theses and Dissertations (Comprehensive)

Study Design. In vivo examination of the influence of TAK-242 (resatorvid) treatment on the mechanical properties of the intervertebral disc (IVD) in secreted protein acidic and rich in cysteine (SPARC) gene knockout (SPARC-null) mice.

Objectives. To examine if chronic TAK-242 treatment mitigates mechanical degradation associated with IVD degeneration in SPARC-null mice.

Summary of Background data. IVD degeneration is associated with low back pain (LBP) and is accompanied by mechanical changes to the spine. SPARC is a protein that contributes to the functioning and maintenance of the extracellular matrix (ECM), with SPARC-null mice displaying accelerated IVD degeneration. TAK-242 is a toll-like …

The Effect Of Loading Rate On Annulus Fibrosus Strength Following Endplate Fracture, John Mcmorran

Theses and Dissertations (Comprehensive)

Low back pain is the most prevalent cause of chronic pain for North Americans, and its correlation with endplate damage, and deficient mechanical properties in the annulus fibrosus (AF) makes this injury particularly concerning. To date, biomechanical alterations in the AF following endplate fracture have not been well described. Owing to the AF’s collagenous composition, and the intrinsic biomechanics of intervertebral discs (IVDs) during compression, it was hypothesized that the mechanical properties of AF specimens would show rate-dependent alterations in their tensile and adhesive strengths following endplate fracture. The purpose of the present study was to quantify the mechanical properties …

A Comparison Of The Stability & Pressure Distribution Between Young Adults And A Transtibial Amputee During Obstacle Crossing, Colin Kirst

Theses and Dissertations (Comprehensive)

Falls are identified as the largest risk and leading cause of injury for multiple populations, including young adults and individuals with a transtibial amputation. Furthermore, obstacle crossing is identified as the number one cause of a trip, which subsequently leads to falling. Previous research provides conflicting results and a lack of specificity in certain outcome measures of dynamic stability during obstacle crossing. Therefore, the purpose of this thesis was to gain foundational knowledge on outcome measures related to dynamic stability during an obstacle crossing protocol. An additional purpose was to investigate the dynamic stability of young adults, and speculate on …

An Investigation Of The Relationship Between Intervertebral Disc Puncture, Inflammation, And Tissue Mechanics Using A Rat-Tail Model., Brigitte Laird

Theses and Dissertations (Comprehensive)

Introduction: The intervertebral disc (IVD) is composed of the annulus fibrosus (AF), which surrounds and contains the nucleus pulposus (NP). It is hypothesized that when the IVD becomes injured, in the case of IVD herniation, a localized innate immune response is initiated. Although the presence of pro-inflammatory cytokines in injured IVDs has been well documented, the extent to which inflammation affects the mechanical properties of the IVD remains poorly understood. The purpose of this study was to determine the effect of IVD damage (via puncture) and inflammation (via lipopolysaccharide (LPS) exposure) on the mechanical and structural properties of the IVD. …

The Effects Of Orthotics And Increased Plantar Sole Mechanoreceptor Activation On Turning Performance In Individuals With Parkinson’S Disease, Kelly A. Robb

Theses and Dissertations (Comprehensive)

Locomotion and turning are complex movement patterns essential to activities of daily living. Individuals with Parkinson’s disease (PD) report difficulties turning, often coupled with impaired balance and increased fear of falling. The purpose of this within-subject study was to determine if orthotics, with and without a textured top cover, can improve gait stability and turning performance within Parkinson’s participants. Seven participants with a diagnosis of idiopathic Parkinson’s disease, aged 55-80 years old, participated in the study. Participants completed three testing sessions; baseline, 4 weeks post-baseline, and 5 weeks post-baseline. The ‘footwear only’ and ‘footwear + non-textured orthotic’ conditions were tested …

The Effects Of A 12-Week Custom Foot Orthotic Intervention On The Intrinsic Muscles Of The Foot, And Dynamic Stability During Unexpected Gait Termination In Healthy Young Adults, Katrina Protopapas

Theses and Dissertations (Comprehensive)

Introduction: Custom-made foot orthotics (CFO’s) are a commonly prescribed intervention to help individuals that are suffering from foot pain and foot disorders. However, the mechanisms of CFO’s are still poorly understood and are not well known. With the plantar intrinsic muscles of the foot being in direct contact with the CFO, it puts these structures at risk for disuse muscle atrophy as a result of being offloaded. Therefore, the purpose of the current study was to determine the effect of a 12-week custom-made foot orthotic intervention on the intrinsic muscles of the foot and dynamic stability during unexpected gait termination. …

The Effects Of Manipulated Somatosensory Input On Simulated Falls During Walking, Sarah Mitchell-Ewart

Theses and Dissertations (Comprehensive)

Previous research has demonstrated that there is a distinct relationship between aging and instability. The somatosensory system plays a significant role in balance control in conjunction with vision and the vestibular system (Qiu et al., 2012). Evidence has shown that manipulation of the mechanoreceptors on the plantar surface of the foot has a direct effect on balance control. By manipulating these receptors with hypothermic anesthesia and vibration, researchers are capable of simulating the effect of sensory modification on healthy individuals, in order to understand the role that plantar-surface sensation has in adapting to perturbation during gait (Perry et al., 2001; …

The Effects Of A Low Back Pain Vibration Modality On Trunk Postural Control, Adam R. Cornwall

Theses and Dissertations (Comprehensive)

Abstract

Introduction: Low back pain (LBP) is prevalent worldwide and is affecting even more individuals as the population ages. There has recently been an increase in production of low back pain (LBP) vibration modality belts that apply localized vibration to the lumbar region of the spine as it has shown to reduce pain. However, vibration is also known to perturb muscle spindles and thus interfere with proprioception. If a LBP vibration modality causes a proprioceptive deficit in the trunk lumbar region it could potentially increase an individual’s risk of injury due to poor postural control. Therefore, the effects of a …

An Exploratory Approach To Manipulating Dynamic Stability: Investigating The Role Of Visual Control During A Precision Foot Placement Task, Russell Cg Kennedy

Theses and Dissertations (Comprehensive)

ABSTRACT

Background: The visual system provides the body with an accurate sensory system; designed to gather information at a distance and acts as a feedforward control mechanism during human locomotion. By doing so, visual information contributes coordination of the head-arm-trunk (HAT) segment and modulating foot placement. The purpose of this study was to examine the effects of a constrained pathway during a complex navigational stone-stepping task on HAT segment control and how the visual system guides locomotion during a complex foot placement task.

Methods: Nine university-aged females (Mean age: 22.5 years old +/-1.75) participated in this study. Participants …

The Influence Of Hip Mobility And Fatigue On Spinal Flexion And Muscle Activation In Rugby Scrum Performance, Joshua D. Clayton

Theses and Dissertations (Comprehensive)

Introduction: Rugby scrumming is a means of restarting play following a minor rule infringement that can occur up to 28 times per game. The scrum poses a significant injury risk, with more days missed due to injury per event than any other rugby activity. Rugby players also have a significantly higher rate of spine injury than the general population, perhaps due to flexion in combination with high compression forces, which has been cited as the main mechanism of injury. Flexion of the spine has also been associated with poor hip mobility and quadriceps fatigue in other athletic tasks and may …

The Effect Of Training Older Adults In Tai Chi And Compensatory Stepping On Balance Control, Hannah L. Moore Miss

Theses and Dissertations (Comprehensive)

Abstract

Introduction: In Canadian society, there is a growing prevalence of older adults and one of the main problems facing this generation today is the risk of falling. Tai Chi (TC) is a martial art that has demonstrated improvements in balance control. It uses a series of fluid movements that engage head, neck and trunk rotation while simultaneously reducing base of support. In addition, it has been demonstrated that training older adults by administering unpredictable perturbations to challenge balance better equips them to react successfully in response to balance perturbations. This study aims to determine the potential balance specific benefits …

Influence Of Planning Resources On Gait Control In Parkinson’S Disease, Frederico P. Faria

Theses and Dissertations (Comprehensive)

Movement disturbances in individuals with Parkinson’s disease (PD) have been associated with difficulties to plan complex actions. Performance of simple and complex actions overloads resources for individuals with Parkinson’s disease (PD). However, it is unclear if central resources required to plan gait adjustments while walking exacerbate gait disturbances of patients with PD. More specifically, it is unclear how gait impairments, sensory processing, and the dopaminergic system influence the load on processing resources (e.g. cognitive load) during the planning of step modifications. In order to investigate the relative influence of these factors on cognitive load and its impact on gait control, …

Gait Initiation Mechanics In Concussed Varsity Athletes, Adam Harper

Theses and Dissertations (Comprehensive)

Concussions are a common and potentially serious injury that affects athletes across multiple sports. More than ever concussions are now at the forefront of sport-related research.

Current research indicates that in a cohort of Canadian junior hockey players examined during the 2009-2010 season showed a rate of concussion at 36.5% of all athletic injuries (Echlin et al., 2010). This rate of concussion injury indicates that proper evaluations and examination tools are key to successful management of concussions. The objective of this study was to determine whether a functional task such as gait initiation is able to quantify stability difference following …