Author: Chung, Wing Yan Claire
Title: Active bodysuit for adult degenerative scoliosis (ADS)
Advisors: Yip, Joanne (ITC)
Yick, Kit-lun (ITC)
Degree: M.Phil.
Year: 2022
Subject: Orthopedic braces -- Design
Scoliosis -- Patients
Spine -- Abnormalities
Hong Kong Polytechnic University -- Dissertations
Department: Institute of Textiles and Clothing
Pages: xix, 198 pages : color illustrations
Language: English
Abstract: Adult degenerative scoliosis (ADS), which is also known as de novo scoliosis, is a condition of the ageing population caused by degenerative changes of spine in individuals who do not have any pre-existing spinal deformities, with a Cobb angle that exceeds 10° in the coronal plane. Globally, there is an approximate overall incidence rate of ADS of 6% for people aged 50 or older, and the average progression of the spinal curvature is 3.3° each year. Patients with ADS usually suffer from progressive lower back pain with radiculopathy and neurogenic claudication, spinal stenosis, and progression of the spinal curve which negatively affect the health-related quality of life. Patients are required to wear a rigid brace to relieve pain, correct their posture and reduce the progression of the spinal curvature, which could lead to the problems of discomfort and pressure sores, and cause psychological barriers to compliance with treatment. In response, this project aims to develop a novel flexible brace that provides adequate corrective forces, as well as improves the wear comfort and aesthetics perspective towards bracing treatment.
To achieve the project goal, this study will carry out four tasks, including: (a) a study on the posture, balance and muscle activity of ADS patients, b) a clinical study that involves radiographic examination and questionnaires to investigate the corrective effect, thermal comfort and psychological impact of an existing active bodysuit, (c) the construction of a finite element model to predict the initial in-brace spinal correction of an existing active bodysuit, and (d) the optimisation of a proposed active bodysuit through material testing and D-optimal design.
The posture, balance and muscle utilisation of ADS patients are still unclear. To enhance current understanding of how ADS contributes to the posture, balance and muscle activity, a total of 10 ADS subjects and 10 asymptomatic subjects are recruited to perform habitual standing and sitting. A three-dimensional (3D) motion capturing system, force platform and surface electromyography are used in this study. The ADS subjects demonstrated higher knee flexion in the standing posture and increased hip and knee flexion in the sitting posture at the convex side of their spinal curvature. Moreover, the paraspinal muscles and lower extremities at the convex side of the spine generally showed increase in muscle activity compared to the concave side. The findings demonstrated that ADS patients change their balance pattern to compensate for the shift of the gravity line caused by spinal deformity and have asymmetrical muscles that are elongated and stretched at the convex side of the curvature.
A clinical study is conducted to investigate the efficacy of the existing active bodysuit in terms of the in-brace correction, health-related quality of life and feedback from the recruited subjects. Most of the subjects experience a reduction of Cobb angle greater than 5 degrees while the pain score is reduced after 3-months of brace wear. However, the initial in-brace correction effect of the 2-hour clinical study is not adequate due to possible influential variables, such as a low compliance rate and the material used for the bodysuit. Therefore, the correction effect of the active bodysuit should be enhanced in order to prevent the progression of spinal curvature as well as maintain the ability of ADS patients to perform daily activities.
Based on the results of the clinical study, the thermal comfort and corrective effect of the proposed active bodysuit are the areas that require more attention. First, different fabrics are sourced, and material tests are conducted for the inner vest. A biomechanical model is then developed and validated by comparing the results with those of an actual radiographic examination. The model also eliminates the problems of repeated radiation exposure, subject involvement, long manufacturing time, and brace wear time when conducting a wear trial. The biomechanical model shows a trend of spinal correction with good accuracy. To optimise the spinal corrective effect of the proposed active bodysuit, the different material properties of the shoulder straps, waistband, and side and middle struts are modified by using a D-optimal design. It is found that the design combination of woven shoulder straps with Young's Modulus of 243 MPa, elastics Young's Modulus of 0.45 MPa, 6061 aluminum alloy and polyoxymethylene provides the highest in-brace spinal correction which reduces the predicted in-brace Cobb angle from 29.2° to 27°. The stiffness of the waistband is regarded as the most important factor in reducing the Cobb angle, followed by stiffness of the side struts, shoulder straps and lastly the middle strut.
The research results in this study enhance current knowledge on the balance, posture and muscle activity of ADS patients, as well as provide useful information for the design, thermal comfort and mechanics of flexible braces to control spinal deformities and maintain daily activities of ADS patients. The use of FEM and D-optimal design provides an objective, efficient and reliable methodology to evaluate the performance of different brace materials in correcting spinal deformities and optimising the effectiveness of the proposed active bodysuit. The output of this project can be extended to the development of similar orthotic devices and textile medical products.
Rights: All rights reserved
Access: open access

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