Functional intimate apparel for adolescents with scoliosis

Abstract

Adolescent idiopathic scoliosis (AIS) is the three-dimensional structural curvature of the spine with unknown etiology which occurs during puberty. Recent survey findings published in 2016 indicate that the prevalence of schoolchildren with AIS in China was 5.14%. Scoliosis not only affects the physical profile such as spinal asymmetry, trunk deformity, shoulder obliquity, scapular asymmetry, and pelvis declination, but also causes spinal pain, restricts physical movement, affects cardiac and pulmonary functions, or even leads to death. Thus, proper treatment for AIS is essential. Rigid bracing is a universal non-invasive treatment for AIS that slows down or stops the progression of the spinal curvature until the bones reach maturity. However, noncompliance with the use of rigid braces is often an issue due to some of the drawbacks of bracing, such as skin irritation, discomfort, loss of aesthetics, and psychological impacts. Therefore, in the last decade, the idea of a flexible brace has been proposed in response to the negative impacts of rigid braces. SpineCor and the posture correction girdle are two examples of flexible braces. Nevertheless, the mechanism and effectiveness of existing flexible braces are still controversial. Therefore, the aim of this study is to develop a novel flexible brace for AIS patients to maximise the performance on spinal correction with the advantage of flexibility and comfort. This study consists of four components including (a) a clinical study on an existing posture correction girdle which involves radiographic examinations, three-dimensional body scanning and interface pressure measurements of subjects with mild scoliosis, (b) the design and development of a functional intimate apparel to treat scoliosis, (c) a clinical study of the proposed functional intimate apparel to investigate the degree of spinal control, spinal contour changes, psychological impact on patients, and effect of the biomechanics of the brace on the interface pressure, and (d) the formulation of a simulation model to predict the effectiveness of the initial in-brace spinal correction of the proposed functional intimate apparel. The effectiveness of the existing posture correction girdle was still unclear. To conduct a background study on the existing design and determine the possible design elements for the proposed functional intimate apparel, a 6-month clinical trial of the original posture correction girdle was first carried out. Subjects were required to wear the posture correction girdle for 6 months. Radiographic examinations of the subjects in three conditions, including pre-intervention, after 6 months of brace wear and after 6 months post-brace wear, were carried out through three-dimensional image scanning, and interface pressure measurements were also done. It was found that the posture correction girdle had a positive effect in controlling the progression of the scoliosis and spinal contour changes. However, the in-brace spinal corrective effect was unsatisfactory. Moreover, the pressure distribution was not even compared to the three-point pressure system, which is the most common system used to exert corrective effects by rigid orthotics. In response to the unsatisfactory in-brace correction of the original posture correction girdle, a functional intimate apparel for AIS was designed and developed in this study. The proposed design adopted a similar corrective mechanism as rigid braces to control the spinal deformity. A conceptual framework for apparel design that is called the functional, expressive and aesthetic model was applied during the design process. A functional intimate apparel prototype that consisted of a bra top, pants, pelvis belt, hinge bone with a cushioning pad and corrective component was designed and developed to maximise the spinal corrective effect of the proposed flexible brace and minimise the negative impacts, such as mobility restriction and discomfort of rigid braces. To investigate the efficacy of the proposed functional intimate apparel, a clinical study was conducted to determine the initial effects of this flexible brace in terms of the in-brace correction, posture changes and quality of life and its biomechanics and the short-term effects on spinal deformity, posture and quality of life. It was found that the initial percentage of in-brace correction ranged between 9.7% and 88.7% with the standard deviation of 33.6. Compared to the original posture correction girdle, the in-brace correction of the proposed functional intimate apparel was significantly greater. Moreover, in considering the effect of posture, it was found that 60% of the subjects corrected their initial posture in terms of reducing the shoulder obliquity and shoulder rotation. Surprisingly, there was no correlation between the initial shoulder asymmetry and in-brace correction. In considering the impact on the quality of life, the results of the brace questionnaire shown that the proposed functional intimate apparel almost never had negative impacts with respect to the general health of the user, physical functions, body pain and social aspects. As for the biomechanics, the interface pressure between the corrective pad and body of the user was measured and found to be similar to that of rigid braces. Apart from the initial effect, the initial spinal correction after 3 months of wear was 52.7%. Furthermore, after three months, the shoulder rotation and posterior trunk symmetry index improved by 29.8% and 13.1% respectively. Also, the results showed that the quality of life did not change drastically after three months of wear. Apart from a clinical study with human subjects, a numerical finite element model was developed to simulate the effectiveness of the in-brace spinal correction of the proposed functional intimate apparel. This model overcame the concerns around human subjects and ethical problems of repeated radiation exposure to examine the scoliotic spine. More importantly, the model could simulate the spinal corrective performance in relation to the position of the pad and loading and material properties of the elastic straps and hinge. The simulation model showed the trend of spinal correction with good accuracy. Moreover, to further investigate the biomechanics of the brace and the effect of the corrective pads on vertebral movement, 15 models with different degrees of thoracic and lumbar loading were constructed. It was found that managing loading from the pads was essential since excessive thoracic loading or insufficient lumbar loading might induce the progression of lumbar curve. The current models showed that a 140% increment in lumbar loading provided the optimum corrective result in both the thoracic and lumbar curves. The research results in this study provided useful information on the design elements and mechanics of flexible braces to treat scoliosis. The functional intimate apparel was a non-invasive means of controlling spinal deformity. This study showed that the textile materials provided adequate corrective forces and resulted in some in-brace correction. The simulation model could be used to predict the degree of in-brace correction and optimise brace designs. The outputs of this project could be extended to the development of other types of flexible orthotic devices and enhance the comfort and flexibility of textile medical products.