Date of Award

Summer 2011

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Biomedical Engineering - (Ph.D.)

Department

Biomedical Engineering

First Advisor

Richard A. Foulds

Second Advisor

Bryan J. Pfister

Third Advisor

William C. Van Buskirk

Fourth Advisor

Sheldon S. Lin

Fifth Advisor

J. Christopher Fritton

Abstract

The first discovery of the potential role that mechanical loading has on determining the strength of bone occurred in 1892. However, for almost a century after this discovery, the specific mechanisms influenced by mechanical loading remained locked in a mysterious 'black box'. Then in the 1960s, the 'black box' was opened and continued work has now unlocked the basic mechanisms involved in mechanical loading and whole-bone strength. This increased knowledge has spurred clinicians and researchers to investigate the impact of weight-bearing interventions on individuals with an increased risk of osteoporosis. The most common weight-bearing clinical intervention used in non-ambulant populations is passive standing. However, insurance companies are increasingly denying reimbursement for standers, quoting that there is not enough scientific literature proving the benefits of the intervention. This study continues the investigation of the impact of passive standing, while introducing and investigating the impact of a novel dynamic stander which mimics the walking gait. A fifteen-month study was initiated to determine the impact of each clinical intervention on bone mineral density, bone mineral content and area in non- ambulant children. Dual-energy x-ray absorptiometry (DXA) was used to calculate the aforementioned parameters as it is the current 'gold standard' in the field, though limitations do exist in the calculation of density, content and area in low density populations. Due to these limitations, this study also investigates potential improvements to the algorithms used in DXA to increase the precision of this study and future work.

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