Author: So, Tsz-wah Patrick
Title: Effects of backrest inclination on spinal posture
Degree: M.Sc.
Year: 2002
Subject: Hong Kong Polytechnic University -- Dissertations
Lumbar vertebrae
Department: Multi-disciplinary Studies
Jockey Club Rehabilitation Engineering Centre
Pages: xiv, 77 leaves : ill. (some col.) ; 30 cm
Language: English
Abstract: The purpose of this study was to investigate the effects of backrest inclination on spinal posture. A non-contact measurement technique with the application of laser sensing technology was established to quantify spinal posture from the lumbar to the cervical region. High repeatability (ICC = 1.0000) and negligible error (Percentage of absolute error = 0.32%) was demonstrated for this technique. The spinal postures (in terms of spinal height and depth) were measured in ten adults for four backrest inclinations. Spinal curvatures of the lumbar, thoracic and cervical regions were estimated, using a numerical method, from the spinal heights and depths measured. Reproducibility of spinal postures at different backrest inclinations was determined using an ICC (3,1) and most of the values for spinal height and depth were above 0.75. Lumbar curvatures were also found to be reproducible for all four backrest inclinations examined (ICC > 0.75), but decreased from thoracic and cervical regions. Repeated measures ANOVA together with post-hoc multiple comparison with Bonferroni correction was adopted to determine the differences in spinal posture at different backrest inclinations. Statistically significant differences were only shown in spinal height, length of spine in contact with the backrest, spinal depth at T12 and the peak of the lumbar region. These differences justified the need for adjustability in these parameters so that the design of back support could then accommodate the changes in spinal posture at different backrest inclinations. Regression analysis was conducted to explore the relationship between spinal posture and backrest inclination. Linearity was demonstrated in spinal heights at all levels but the coefficient of determination values only ranged from 0.173 to 0.691. The limited power of using the degree of backrest inclination to predict spinal posture favoured user adjustment of the height of the back support (at different levels) rather than a built-in backrest design with automatic rectification. This study served as a starting point far investigations into how spinal posture adapts to different chair designs. Future studies could include a series of investigation scomposed of postural evaluation and spinal loading measurements combined with the chair-users' ratings of comfort level. In this way, a model of optimal sitting posture for the entire spine could possibly be developed and utilized in the design of the shape/contour of the backrests of chairs.
Rights: All rights reserved
Access: restricted access

Files in This Item:
File Description SizeFormat 
b16277338.pdfFor All Users (off-campus access for PolyU Staff & Students only)6.07 MBAdobe PDFView/Open

Copyright Undertaking

As a bona fide Library user, I declare that:

  1. I will abide by the rules and legal ordinances governing copyright regarding the use of the Database.
  2. I will use the Database for the purpose of my research or private study only and not for circulation or further reproduction or any other purpose.
  3. I agree to indemnify and hold the University harmless from and against any loss, damage, cost, liability or expenses arising from copyright infringement or unauthorized usage.

By downloading any item(s) listed above, you acknowledge that you have read and understood the copyright undertaking as stated above, and agree to be bound by all of its terms.

Show full item record

Please use this identifier to cite or link to this item: