Development of a posture monitoring system

Pao Yue-kong Library Electronic Theses Database

Development of a posture monitoring system


Author: Wong, Wai-yin
Title: Development of a posture monitoring system
Degree: Ph.D.
Year: 2009
Subject: Hong Kong Polytechnic University -- Dissertations.
Posture disorders -- Diagnosis.
Spine -- Abnormalities -- Diagnosis.
Department: Dept. of Health Technology and Informatics
Pages: xix, 302 p. : ill. ; 30 cm.
Language: English
InnoPac Record:
Abstract: Spinal deviations including lateral curvature, rotational deformity, hyper/hypo-kyphosis and hyper/hypo-lordosis, could be associated with some spinal diseases such as idiopathic scoliosis, Scheuermann's disease, osteoporotic vertebral fractures or low back pain. Spinal diseases occur at different stages of life span from growing population to working population and then extending to aging population. These diseases might relate to physical and social problems of the patients and would impose a major burden to the society via work absenteeism and high health care costs. Therefore, an effective posture assessment and training would be helpful for improving a person's quality of life and reducing the social burden. For posture assessments of the spine, radiography and motion analysis systems are commonly used. However, the operations of these systems are confined within the laboratory or clinical environments, and the measurements cannot provide any posture information in daily situations. As a non-surgical treatment to some spinal diseases, the conventional orthotic intervention is to apply passive forces to the patient's body via a spinal orthosis for controlling the spinal deformities and maintaining a good trunk alignment. However, once the orthosis is removed from the body, its functions can no longer be kept. Therefore, an active posture training approach should be postulated in suitable clinical cases as it can keep the trunk in an appropriate posture via using the patient's own back muscles and a long-lasting effect can be accomplished. This can also facilitate the refinement of upright posture awareness and prevention of deterioration of spinal diseases. A portable posture monitoring system, which can measure parameters related to the spinal curvature, could be used for providing posture information of daily activity and improving the effectiveness of posture training. In this thesis, a portable posture monitoring system has been developed, which consists of 3 inertial sensor modules, a data logging and feedback system, an integrated garment, and with additional software for analysis of posture information and visual display software for providing posture training. The sensor modules were used for tracking the trunk posture change at the thoracic and lumbar regions in the sagittal and coronal planes relative to a neutral position, in terms of curvature alteration measured between adjacent sensor modules. An auto-reset algorithm has been developed and integrated into the measurement system for minimizing the measurement errors due to the inherent limitations of the inertial sensors. In the evaluation process, the measured posture change was compared with the total change of the inter-segmental angles of the trunk measured by a motion analysis system. The results showed that inertial sensor modules could provide trunk posture information of the thoracic and lumbar regions and its measurements were found to be comparable to those of the motion analysis system (averaged RMS differences <4.5o for the sagittal plane and <3.5o for the coronal plane, and correlation coefficient is >0.824 in dominant planes of movements during flexion and lateral bending). The system has been used to monitor posture changes of healthy human subjects and patients with adolescent idiopathic scoliosis during daily activity. The results demonstrated that the subjects could alter their postures with an audio-biofeedback signal provided. This verified the potential of the developed system in facilitating posture training. With this promising result, it is worthy for further developments and enhancements. The ultimate goal of this system is towards the applications in occupational health promotion as a prophylactic measure for those jobs with a high-risk of low back pain as well as a treatment option for the patients with posture deviations or spinal diseases.

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