國立成功大學 生物醫學工程學系 博士論文

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1 國立成功大學 生物醫學工程學系 博士論文 氣囊式脊椎裝具對脊椎側彎患者矯正效果的 評估 Evaluation of Airbag Spinal Orthotic with Scoliosis Patient 研究生 : 楊文杰 (Wen-Chieh Yang) 指導教授 : 張志涵 (Chih-Han Chang) 中華民國一百零三年五月

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3 中文摘要 青春期原發性脊柱側彎 (AIS) 是一種好發在孩童脊柱的畸形病變 病理上, 在身體發育期間當椎骨兩側的生長速度不相等時會造成椎骨兩側厚度的不同而造成脊柱畸形 脊柱兩側的肌肉在長度 - 張力的關係上也會因彎曲而導致不平衡的現象, 結果將增加側彎的嚴重性及惡化的速度 脊柱側彎的患者除有不良姿勢外, 還會因引發心肺功能的嚴重傷害及肌肉神經系統的疼痛而造成日常生活機能的障礙 根據文獻報告僅有背架治療與外科手術才能有持續性且有效的控制側彎的惡化和矯正的效果 Airbag brace 是改良自 Boston Brace 一種新式的矯正型背架, 其提供的矯正力量除來自背架後面的張力性束帶外, 更可由內襯在背架底層的氣囊以充氣的方式來增加推動脊柱所需的壓力 本研究以 20 位 6 至 16 歲穿戴自己的 Airbag brace 的 AIS 患者並來討論本裝具在臨床上矯正的效果與在不同活動時背架對肌肉的作用 經統計顯示不僅在矯正及減少側彎角度上有顯著作用外, 與一般背架的最大不同處在於脊柱側彎的曲線與角度的減少是在移除背架後經 X-ray 顯現才來的結果, 不同於其他背架是在穿著下所顯示的矯正效果 本研究在探討 Airbag brace 在矯正上的兩種因素, 外在因素 : 皮膚 - 裝具界面的矯正力 ; 內在因素 : 豎脊肌 (Erector Spinae) 的活性, 透過這兩種因素來了解背架在不同動作或姿勢時對身體的作用壓力 接觸面積及對背部肌肉活性的影響 藉此可提供改良背架的組件與力學原理, 也能給予側彎患者進行治療性運動時另一種方法以增加矯正的效果 在研究的結果顯示, 以可加壓變形的 airbag 取代固定形態的 pressure pad 是可行的, 不管在接觸壓力 接觸面積和力量上 (8.91±4.19 kpa, ±73.96 cm 2, and ±187.8 N) 和之前的文獻相似, 並且在不同的動作 / 姿勢下這三種參數都能保持在一定的範圍內 另外, 在 I

4 患者固定回診的檢查下顯示 Airbag brace 在減少側彎角度上有顯著的效果 (p <0.05, 矯正前 (33.14±9.36) 矯正後(21.82 ± 10.32)) 另外, 比較在相同動作下背架對肌肉影響的結果, 其差異經肌電訊號顯示背架確實對肌肉的活性有顯著影響, 特別是在 trunk upright flexion extension 以及 rotate to concave side 等動作 (5.11±2.2, 20.33±3.2, 9.08±3.8 及 8.24±2.3) 然而, 在沒有穿戴背架時各動作間的肌肉活性並無任何差異, 但在有背架使用時不同動作間的肌肉活性即顯現出差異性, 特別是 trunk flexion 及 extension 等動作會較左 右兩側彎有更大的活性表現 在進行脊柱兩側肌肉活性的比較時發現, 無背架的作用下僅在轉向凸側的動作中其兩側的肌力有顯著差異 (4.21±0.9,t=3.46) 然而在背架作用下彎向凸側 (1.83±0.2, t=2.46) 與轉向凸側 (2.49±0.6,t=2.71) 等動作的兩側的肌力有顯著的差異 由於正常脊柱和側彎的脊柱在動作型態上會有所不同, 例如正常脊柱的椎體在身體進行側彎與軸向旋轉時的轉動方向和身體相同, 但在脊柱側彎的椎體則是相反 另外, 控制脊柱動作的肌肉群不僅複雜且精細加上脊柱側彎有數種不同的型態, 因此不同患者在執行同一動作時可能會有不同的動作策略, 也就更增加了研究上的複雜與困難 當本研究以 Airbag brace 來矯正與減少側彎角度時, 不僅可在不同姿勢下維持一致性的矯正壓力與接觸面積外也可增加背部肌肉的活性 就研究結果與臨床理論比較, 相同之處在於不建議患者往側彎的凹側彎曲即使是穿著背架, 而不同處在於建議可穿著背架時進行矯正動作的訓練, 特別是身體的 upright flexion extension 和彎向與轉向凸側動作 關鍵字 : 脊柱側彎,Cobb 角度, 氣囊式背架, 背架內運動 II

5 Abstract Adolescence idiopathic scoliosis (AIS) is a spinal column deformity that often occurs in children during adolescence. Pathologically, when the growth speed on both sides of the vertebral is unequal, the thickness of the vertebral body is different and leads to scoliosis. Consequently, the length-tension relationship of the muscles on the sides of the spine is imbalanced progressively. Patients with scoliosis have poor posture and may even have poor cardiopulmonary function when this condition becomes severe. Pain accompanied by neuromuscular dysfunction may cause Activities of daily living (ADLs) disability. According to research, only bracing treatments and surgical operations can effectively control the deterioration and correction of scoliosis. The correction principal of a traditional brace is based on a three-point compression system. The brace gives opposite force to the apex of the curve and fixation to both ends at the same time. As a result, a traditional brace is used to treat curves with Cobb angles between 20 degrees and 45 degrees. According to clinical statistics, among traditional braces, the Boston Brace has the best correction effect. However, it can only maintain and avoid deterioration of the spine. Hence, a lot of medical experts believe that the brace can only maintain and does not treat or correct. Because reduction of the Cobb angle is often only shown on the X-ray of the patient with a brace, and once the brace is removed, the Cobb angel returns to the initial condition. The airbag brace is modified from the Boston Brace. Its corrective force comes III

6 from not only the tension stripe behind the brace, but also from an airbag filled with air within the brace to increase the pressure pushing on the spine. This study targets 20 AIS subjects (aged 6-16) and supplies them with their own airbag braces in order to do research on the corrective effects. The data analysis of the results indicates effective correction. Compared with the Boston Brace, the most significant difference is that a reduction in the Cobb angel is obtained after the brace is removed. This research is intended to discuss two factors related to the airbag brace: 1) the external factor, consisting of the corrective force of the skin-orthotic interface, and 2) the internal factor, consisting of the back muscle (erector spinae) activity in order to understand how the interface pressure, contact area, and muscle activity are influenced by an airbag brace and exercise. The use of this brace not only improves the components of any brace but also introduces a new therapy to exercise therapy to increase the correction effect. The results show that it is workable to replace a fixed shape brace with an air bag that is deformable with pressure. The contact pressure, contact area and force (8.91±4.19 kpa, ±73.96 cm2, and ±187.8 N) are similar to those of an earlier research paper, and the three parameters stay within a certain range. Moreover, a long track indicates that the airbag brace has a significant effect on reducing the Cobb angel (p <0.05 between the results before (33.14±9.36) and after (21.82 ± 10.32) the correction), especially the final angel, as shown in the X-ray taken after the brace is removed. It s quite different from the traditional effect, which only occurs when the brace is worn. In terms of the influence that the brace and movements/gestures have on IV

7 muscle activities, the results indicate that the brace does have a significant influence on muscle activity. Trunk uprightness, flexion, extension, and rotation to concave side movements exhibit obvious differences (5.11±2.2, 20.33±3.2, 9.08±3.8 and 8.24±2.3). Furthermore, without the brace, there are not any differences among all the movements, but the use of brace results in significant differences, especially in the case of trunk flexion and extension. Under the use of the brace, bending to the right and left sides incorporates more muscle activity. When comparing the muscle activity on both sides of the spine, it is shown that, without the brace, the muscle activity on both sides is obviously different only in regard to bending to the convex side (4.21±0.9, t=3.46). However, with the brace, the muscle activity is significantly different in the movements of bending to convex side (1.83±0.2, t=2.46) and rotating to convex side (2.49±0.6, t=2.71). The airbag brace, which replaces the pressure pad with a deformable airbag, has better effect on reducing the Cobb angle than the traditional brace. It maintains consistent correction pressure and contact area during different gestures and increases back muscle activity. The muscles involved in spinal movements are quite complicated and delicate, and in normal movement patterns, the rotating directions of the spine and the body are the same. However, the AIS spine shows the opposite direction during a static gesture. Also, because different patients have different movement strategies when conducting the same movement, the complexity and difficulty of the research is increased. Comparing the research result with that of clinical results, the same issue is that bending to the concave side is not suggested even with the brace. The difference between the two treatment modes is that exercise therapy training can be conducted with the brace. Upright position, flexion, V

8 extension, bending and rating to the convex side are especially recommended. Key word: Scoliosis, Cobb angle, Airbag brace, In-brace exercise. VI

9 誌 謝 終於畢業了, 能夠從成功大學的生物醫學工程博士班畢業我最感謝的是指導老師張志涵教授 從成大醫學工程研究所碩士班開始我就受教於老師的指導, 碩士畢業後即從事臨床的物理治療工作直到多年後到仁德醫專擔任講師, 因教職的需求而回成大考取博士班再重新當學生 在就讀博士班期間即要回苗栗教書又得回台南當學生, 因此在課業與研究上往往無法趕得上進度, 特別是實驗所需的儀器多虧老師幫助才能組建, 更麻煩的是日後的資料分析以及論文修正投稿等更讓老師花了很多的時間才得以完成, 所以我能畢業對老師的幫忙倍為感激 另外我要感謝劉建志醫師對我在實驗及研究上的幫助 雖然我對背架在脊柱側彎的矯正相當有興趣, 特別是改善背架的設計等, 但這也僅單純是一種構想 所以當研究開始才發現患者要從何處來以及背架找誰幫忙製造等才是最大的難題 在背架的改良設計上我一直想用氣囊來取代壓力墊, 但在台灣的背架製造公司是以商業利潤取向, 所以我只好找成大醫院復健科義肢裝具室的學弟何浩南並感謝他幫我製造簡單的背架才能進行初步的實驗及修改實驗設計等事項 就在我的研究進入一個瓶頸時, 在朋友的介紹下我認識了劉醫師 他是回國多年的 Chiropractor 醫師並且從事脊柱側彎的矯正多年, 更巧合的是他所開發的裝具也是利用氣囊取代壓力墊 在如此機運下前去拜訪他並在他的幫助下我才能獲得研究的成果, 在此再次感謝劉醫師對我在脊柱側彎治療及矯正方法的指導以及研究上的幫助 除此之外, 我還感謝實驗室的佳文 薇清在我無法回成大時幫我跑一些公文流程以及國誌幫我排版修正論文格式, 另外感謝暐勳 耀德 江喻及彥年等其他已畢業的學弟妹們在我實驗需要人手時能不吝幫忙, 在此祝福他們能心想事成 VII

10 Contents 中文摘要... I Abstract.....III 誌 謝 VII Contents VIII List of Tables......XI List of Figures......XII CHAPTER Introduction Scoliosis Spinal orthotic (Brace) Correction principle of orthoses to vertebra deformity Indications for bracing treatment for scoliosis Types of traditional orthoses Literature reviews The clinical effect on traditional orthoses Other literature on the biomechanics of spinal orthotics The faults of bracing treatments The effect of therapy exercise on scoliosis The effect of biofeedback on scoliosis Research objective VIII

11 CHAPTER Methods and Materials The manufacturing procedure for the 3D Airbag brace The correct principle of the 3D Airbag brace The manufacturing process for the brace Subject information Material/instruction setup Measurement pressure on the skin-orthotic interface Measurement the muscle activity using an EMG Data collection procedure Data analysis The effect of correction from calculable Cobb angle The analysis of three parameters The surface EMG treatment and analysis CHAPTER Results The correct effect for the 3D Airbag brace Interface pressure, contact area and force muscle activity on superficial back muscle group (Erector Spinae) Influence of using a brace on muscle activity during different exercises The difference between muscle activity during different exercises under the same conditions IX

12 3.3.3 The influence of the brace on the bilateral muscle activity of the spine CHAPTER Discussion The mechanism and advantages of the 3D Airbag brace for correcting IS The effect of correction of IS by the 3D Airbag brace The effects of a wearing the Airbag brace on the back muscle activity of AIS patients CHAPTER Conclusion Reference X

13 List of Tables Table 2.1 Data for subjects with thoracic curve Table 2.2 Data of subjects with lumbar curve Table 3.1 The differences in the Cobb angle after removal of the brace before and after correction Table 3.2 Statistical outcomes of airbag brace treatment at thoracic and lumbar curves...43 Table 3.3 The measured interface parameter values during exercise...48 Table 3.4 The EMG RMS of in- and out-of-brace exercises with difference postures Table 3.5 The paired samples t- tests to test differences between in-brace and out-of-brace exercises under the same postural conditions.51 Table 3.6 Correlated sample one-way ANOVA of repeated measures to analyze out-of-brace exercises...53 Table 3.7 Correlated sample one-way ANOVA of repeated measures to analyze in-brace exercises...53 Table 3.8 The EMG value ratios on both sides of the spine in the out-of-brace exercise condition...55 Table 3.9 The EMG value ratios on both sides of the spine in the within-brace exercise XI

14 List of Figures Figure 1.1 A normal curve of spine and back muscles (Clay, J. H., 2008) Figure 1.2 (a) is the photo of scoliosis ( and (b) is the vertebra body rotation direction. (Bunch and Patwardhan 1989) Figure1.3 (a) and (b) illustrate the surgical procedure for scoliosis ( com/mmko7.jpg)...7 Figure 1.3 (c) x-ray of surgical intervention in scoliosis. (Bunch and Patwardhan, 1989) Figure 1.4 Scoliosis produced by imbalanced force between Ft (tension force) and Fc (compression). (Veldhuizen, Cheung et al. 2002)....8 Figure 1.5 Scoliosis can occur as a result of vertebra rotation. (Veldhuizen, Cheung et al. 2002) (Chase, Pearcy et al. 1993) Figure 1.6 External force used to push the apex on scoliosis curve. ( 7.pdf)...10 Figure 1.7 The Cobb angle can be shown by an X-ray to confirm the correct effect of a brace Figure 1.8 Milwaukee CTLSO ( Figure 1.9 The Boston Brace ( Figure 1.10 The Wilmington Orthosis ( XII

15 on41)...14 Figure 1.11 Charleston bending Brace ( Figure 1.12 The three-point compression system used in a brace design. The two F1 force are supporting forces, while the F2 is the push force Figure 2.1 Correction moments for rotated vertebra; Fr is the rotational force couple on the vertebrae; Fa and Fp are the antagonistic forces working on the anterior and posterior side of the trunk Figure 2.2 Original brace (a) anterior view (b) posterior view...27 Figure 2.3 The airbag component (a) flat shape (b) after filled with air.28 Figure 2.4 (a) Brace accomplished from anterior view (b) superior view. (c) The subject with her brace (d) the X-ray film with brace..29 Figure 2.5 Tactilus pressure mat (Sensor Products Inc.; Madison, New Jersey) 33 Figure 2.6 The EMG instrument (Telemyo 2400T, Noraxon Inc., USA)...34 Figure 2.7 the coil of the 2D Goniometer was first placed on the apex of the curve, and then the sensors were fixed on both ends of the upper and lower spine. The surface electrode pads, connected to channels 1to 6, were attached to the skin on both sides of the spine along the three parts of the 2D Goniometer...36 Figure Upright posture Figure Trunk flexion Figure Trunk extension Figure Left side bending Figure Right side bending...38 Figure Right axial rotation...38 Figure 3.1 (a) The AP X-ray films before the follow up period of one subject without XIII

16 the brace. (b) The AP X-ray films after the follow up of the same subject without the brace...42 Figure Upright (Average pressure: 8.2Kpa, Contact Area: cm2, Force: 319 N)...45 Figure Flexion (Average pressure: 10.7 Kpa, Contact Area: cm2, Force: N) Figure Extension (Average pressure: 9.2 Kpa, Contact Area: cm2, Force: N)...46 Figure Bending to the concave side (Pressure: 9.4Kpa, Contact Area: cm2, Force: 336.7N)...46 Figure Bending to the convex side (Pressure: 9.3 Kpa, Area: 397 cm2, Force: 367.2N) Figure Rotation to the concave side (Pressure: 7.5 Kpa, Area: cm2, Force: 276.7N)...47 Figure Rotation to the convex side (Pressure: 7.4 Kpa, Area: cm2 Force: 310 N)..47 Figure EMG Row data for the extension without the brace...49 Figure EMG RMS data for the extension without the brace Figure 4.1 The x-ray films show an anti-current image. (a) before without a brace, (b) after with bracing Figure 4.2 Continuity treatments show the Cobb angle progressive decreases over an 18month period Figure 4.3 Scoliosis movement to change the angle: (a). erect posture, the right convex on the thoracic and the left convex on the lumbar. (b). left lateral bending, the angle change on the thoracic increases and decreases on the lumbar. (c). right lateral XIV

17 bending, the angle change on the thoracic decreases and increases on the lumbar Figure 4.4 X-ray showing the curve of spine may be changed by the airbag brace. (a) Without the airbag brace, the curve occurred in the thoracolumbar region. (b) With the Airbag brace, the spine can be made erect by the brace in the thoracolumbar region...66 XV

18 CHAPTER 1 Introduction The spine is a kinetic link which consists of 26 vertebrae and fibrocartilage discs, the muscles distributed over vertebral periphery that control the action of the spine, and the ribs attached to the thoracic vertebra to help respiration and protect the structure of the cardiopulmonary system (Ashton-Miller 1998) (Figure 1.1). Therefore, the functions of spine are the following: 1. Supporting the trunk and framing the body shape. 2. Conducting the body weight and controlling the posture. 3. Protecting the viscera and nerves. Figure 1.1 A normal curve of spine and back muscles (Clay, J. H., 2008) 1

19 If the vertebras or spine have an abnormal shape, the trunk will exhibit poor posture, and the functions of the spine will be lost. Scoliosis is an abnormal arrangement of the spine, which makes the spine deviate progressively from the midline of the trunk to one side or both sides. If scoliosis occurs before the adolescent spine matures, it is easier for the degrees of the curve to increase and for deterioration to occur. Without prevention and correction, growing children often suffer from incorrect posture and the pain generated by the back muscles. Serious scoliosis may even result in impairment of cardiopulmonary function. Consequently, scoliosis formed in adolescence is called Adolescent Idiopathic Scoliosis (AIS). In research papers on this topic, six ways to prevent and treat AIS have been discussed, including therapeutic exercise, ES, biofeedback, manipulation, bracing treatments and surgical intervention. Only bracing and surgery can control and correct the curve continuously and effectively. Because surgery for scoliosis is an intrusive medical treatment, which not only does harm to the body structure but also causes limits to the patient s growth and movements, it is generally performed on a patient whose curve is progressive or in an individual with a Cobb angle of over 45 degrees. At the same time, bracing treatments do not have the effective and obvious effects on deterioration prevention that surgical intervention does. It is therefore a comparatively safe and conservative treatment. Bracing treatment is usually prescribed to scoliosis patients with Cobb angles between 10 to forty degrees. It is mainly used as a corrective treatment to prevent continuous deterioration. Although brace correction theory can be studied and explained as a corrective biomechanical method of treatment, the soft tissues attaching to the bones are mostly responsible for controlling and influencing skeletal arrangement. Few studies have investigated the influence that a brace has on the soft tissues, especially on the muscles, 2

20 during the correction period. At present, the correction theory, treating the abnormal joints and limbs using a brace is interpreted using the biomechanical concept of creep, in which a time-dependent strain or deformation of a material occurs in response to continuous force or constant stress. Therefore, the aim of this study is to develop and evaluate the design of a 3D airbag brace for the correction of idiopathic scoliosis. The brace is improved from the traditional Boston brace, in which a non-adjustable general hard pressure pad is placed in the lining, and the principle of treatment is derived from a three-point compression system to a multi-point compression depending on the number of adjustable pneumatic airbags that are installed. 3

21 1.1 Scoliosis The pathology of idiopathic scoliosis occurs on the rotation of several vertebras, which can change the shape of the spine and thus result in a complex 3D deformity of the spine (Figure 1.2). This causes the spine to deviate progressively from the midline of the trunk until the vertebra is mature, and the spine will not recover from the deformity (Castro, 2003; Garz On-Alvarado, 2011). This can cause the patient to have abnormal posture, back pain, and poor cardiopulmonary function, among other symptoms. (Perie, Aubin et al., 2003) (Veldhuizen, Cheung et al., 2002) (a) (b) Figure 1.2 (a) is the photo of scoliosis ( and (b) is the vertebra body rotation direction. (Bunch and Patwardhan 1989) Furthermore, most diseases, such those occurring in the neuromuscular and skeletomuscular systems, can induce idiopathic scoliosis so that a fault ratio in the length-tension of muscles and an imbalance tension in the soft tissue at the bilateral spine can be produced (Ashton-Miller and Schultz, 1988). In order to maintain and stabilize a 4

22 smooth spinal curve in different postures and motions, normal musculoligamentous structure and tension may be required (Bunch and Patwardhan, 1989). Therefore, when a scoliosis patient shows abnormal posture or uncoordinated movement, the imbalanced tension of the soft tissue has been present for a long period of time. In other words, the main cause of scoliosis is a vertebra rotation on the curve locality, in which the body of vertebra rotates toward the convex side of the curve and the spinal process opposes the concave side(veldhuizen, Cheung et al. 2002). In addition to this, the curve of scoliosis can be enhanced by having habitual poor posture or motion over a long period of time so that the length and tension of the soft tissue in the bilateral spine may be progressively imbalanced. Therefore, a successful treatment can be to simultaneously deal with the two problems of the rotary vertebra and the imbalanced tension/length of the soft tissues (Odermatt, Mathieu et al. 2003; Perie, Aubin et al. 2003). 5

23 1.2 Spinal orthotic (Brace) All of the methods that currently treat scoliosis such as physical therapy, biofeedback, manipulation, electrical stimulation, bracing treatment, and surgical operation, etc. (Seymour 2002), are used to repair the normal shape of the spine or to decrease the Cobb angle. A study point out, however, the use of orthoses was significantly more successful than both electrical stimulation and observation in other non-operation treatment of idiopathic scoliosis (Rowe, Bernstein et al. 1997). Most research has indicated that only two methods, bracing treatments and surgery, can successfully correct idiopathic scoliosis. However, surgical intervention is usually reserved for severe scoliosis, which is a case in which the curve exceeds 45 degrees in the Cobb angle. Also, the main purpose of the operation is to cease further development in the curvature of the spine, but the trunk s motion may be limited or decreased as a result (Wong, Mak et al., 2000; Goldberg, Moore et al., 2001; (Danielsson, Nachemson et al., 2001) (Figure 1.3). The bracing treatment can usually be applied for a Cobb angle that is smaller than 40 degrees, so the brace is often used to correct and prevent moderate scoliosis. 6

24 (a) (b) Figure1.3 (a) and (b) illustrate the surgical procedure for scoliosis ( MMKo7.jpg) Figure 1.3 (c) x-ray of surgical intervention in scoliosis. (Bunch and Patwardhan, 1989) (c) 7

25 1.2.1 Correction principle of orthoses to vertebra deformity The spine consists of 24 bony vertebrae and cartilage discs, so it can be considered to be an unstable structure which needs the musculoligamentous system around the spine to retain posture and provide the ability to do action. A biomechanical report indicated (Galante, Schultz et al., 1970; Lou, Raso et al., 2002; Veldhuizen, Cheung et al., 2002) that when a balance between the tension of the soft tissue of the posterior column and the compressive force of the vertebral body can be reached, the normal tension on sagittal curve of the spine may be stabilized, and transversal components can be caused by the force in the sagittal plane. In addition, a physiological sagittal curve has been produced by the shape of the intervertebral discs in which the anterior side is wider than the posterior side at the cervical and lumbar regions. A similar process in the mechanical condition can be produced in the case of idiopathic scoliosis. However, the balanced force between the compression force and the tension force may be destroyed so that the curvature of scoliosis is increased (Veldhuizen, Cheung et al., 2002) (Figure 1.4). Figure 1.4 Scoliosis produced by imbalanced force between Ft (tension force) and Fc (compression). (Veldhuizen, Cheung et al. 2002) These forces are able to produce a lateral shear force on the anterior side that pushes the vertebral body outward and may simultaneously have an inverse lateral shear force on 8

26 the posterior side that holds the vertebra in the same place. Therefore, both these relative lateral shear forces can be offset by a torque which can be produced by the posterior soft tissue and the anterior bony component of the vertebrae, so the curvature of the spine can reach a balanced state, but the vertebrae and ribs can exhibit a deformed shape.(veldhuizen, Cheung et al., 2002; Chase, Pearcy et al., 1993) (Figure 1.5) In addition, the apical vertebral body at the curvy region can be pushed farther away from the midline of the spine by a lateral force. However, in order to stabilize the trunk, the back musculoligamentous structure needs contraction or shortness, which is able to diminish the deviations in the spine at the vertebra on the concave side. Figure 1.5 Scoliosis can occur as a result of vertebra rotation. (Veldhuizen, Cheung et al. 2002) (Chase, Pearcy et al. 1993) According to the above statement, scoliosis may be prevented, arrested, and corrected with regard to the development of a spinal curve by using a method that can produce a force in an opposing direction that offsets the pushing force at a specific level (Figure 1.6). This method may be a better choice than non-surgical treatment (Wong and Evans, 1998). Therefore, a back orthotic is a device designed to provide a persistent external force, which 9

27 can reverse the transverse pushing force. Figure 1.6 External force used to push the apex on scoliosis curve. ( Compared to surgery, in addition to the fact that it is not a surgical option and that it provides long-term correction, the bracing treatment has few complications (Rowe, Bernstein et al., 1997). However, if the amount and period of external or corrective force that is applied at the trunk is insufficient during treatment or correction using a brace, not only will the vertebra that diverged from the midline of the body not be restored to the normal position, but it will be impossible to elongate the short, soft tissues on the convex side of the curved spine (Wynarsky and Schultz, 1989). Therefore, an accurate amount and long enough period of external force is needed for an effective correction of the curvature of the spine in order to change the properties of the imbalanced soft tissues. It is essential that the proper position or locality at which the external force is applied at the site of the curve can be obtained (Bader, 1993) (Figure 1.7). A faulty position may decrease the effect of the corrective force pushing the vertebra to 10

28 reach the midline of the trunk, and the curve can in turn progressively increase. So far, an effective brace treatment for idiopathic scoliosis has been dependent on a tailor-made brace that should be accurately manufactured by an orthotist or health care professional, and the patient can readily wear it until the end of the growth plate is achieved or a desired treatment goal is found. Figure1.7 The Cobb angle can be shown by an X-ray to confirm the correct effect of a brace Indications for bracing treatment for scoliosis 2003): Bracing treatments in cases of scoliosis are as follows (Emans, Hedequist et al., degree: generally only observed degree: curves are observed if the curvature increases by more than 5 degrees between skeletally immature, the use of a brace is indicated. 11

29 degree: these patients are at high risk of deformity and may rapidly progress beyond the ability of the brace to prevent degree: bracing treatment if growth continues degree: These curves usually require surgical, however, if the patient has a good-balanced spine, and the curvature is pliable, there may be some advantage to the application of a brace rather than surgery. In very young patients, brace may delay progression long enough to allow further trunk growth before the skeletally mature. The uses of an orthosis for intervention of scoliosis include the cessation of the progression of spine curvature, the prevention of increases in the curvature, gaining permanent correction in anticipation of skeletal maturity and allowing for continued growth of the spine during adolescence, and ideally, a fusion should not be performed in the juvenile years because of the possibility of limiting trunk growth Types of traditional orthoses Traditional braces, such as the Milwaukee CTLSO, the Boston Brace, the Wilmington Orthosis and the Charleston Bending Brace can be designed for supporting or sustaining structural (Seymour, 2002). This design is an attempt to provide a relative counterforce to resist the transverse pushing force, which can cause scoliosis, and to maintain more normal posture in the long-run. 1. Milwaukee CTLSO (Figure 1.8) The Milwaukee CTLSO was first used in 1945 and was a crude orthosis with turnbuckles on the sides and a rigid screw fixation of the thoracic pad. In the 1950s, 12

30 the turnbuckles were abandoned and replaced by three extensible uprights, one anteriorly and two posteriorly. Distraction of the thoracic spine is possible with a flat, firm chin pad and a notched occipital support mounted on a neck ring. (Seymour 2002) Figure 1.8 Milwaukee CTLSO ( 2. Boston Brace (Figure 1.9) The Boston brace was developed in 1972, at Children s Hospital in Boston. It is a prefabricated orthosis available in six sizes, which comes as a mass produced polypropylene module that the orthotist alters to fit the individual patient. This orthosis is often used for curves between 20 and 45 degrees. The Boston Brace opens posteriorly and is primarily designed for a lower scoliosis condition, below T8. (Seymour, 2002) 13

31 Figure 1.9 The Boston Brace ( 3. Wilmington brace (Figure 1.10) The Wilmington orthosis is a custom-molded TLSO that is fabricated in one piece from thermoplastic material. Construction begins with a negative mold formed from the trunk, and then the brace is built around a positive mold. (Seymour, 2002) Figure 1.10 The Wilmington Orthosis ( on41) 4. Charleston bending Brace (Figure 1.11) 14

32 The Charleston Bending Brace, developed in 1978 in Charleston, is a nighttime bending orthosis that holds the patient in reversed position from the scoliotic curvature. This orthosis is molded in maximal reverse bending so that the curvature is forcibly straightened to the greatest degree allowed. (Seymour, 2002) Figure 1.11 Charleston bending Brace ( 15

33 1.3 Literature reviews The clinical effect on traditional orthoses Several studies have compared the effectiveness of different orthoses; one study compared the use of a Boston Brace, a Charleston orthosis, and a Milwaukee orthosis used by 177 patients. The results indicated that the Boston Brace is excellent for preventing curve progression in the case of adolescent idiopathic scoliosis. Another study indicated that the Boston Brace is more successful in preventing curve progression and in averting the need for surgery than is the case with the Charleston Bending Brace (Katz, Richards et al., 1997). Follow ups on the Boston Brace to study the effect of correction with AIS had the following results: A study of 295 patients who wore a Boston brace found that 39% achieved a correction of 5-15 degrees and that 4% achieved more than a 15 degree correction compared with preorthosis curves. Young age at the initiation of orthosis wear and greater preorthosis curvature increased the incidence of surgery (Emans, Kaelin et al., 1986). In a study of 40 adolescents, the Boston brace reduced the Cobb angle of the thoracic spine by 19-27%. (Labelle, Dansereau et al., 1996) The Boston brace was found to be effective in the conservative treatment of idiopathic scoliosis, and the corrective ability seemingly does not deteriorate with a change in the brace design from 0 to 15 degrees lordosis (Olafsson, Saraste et al., 1995). These long-term data confirm that the Boston brace when used 18 or more hours per day is effective in preventing progression of large curves for a mean of 9.8 years after bracing is discontinued (Wiley, Thomson et al., 2000). 16

34 Comparing the Milwaukee CTLSO with the Boston Brace. One study of 244 girls with AIS found that the Milwaukee brace had a five times greater risk of failure than the Boston Brace, and the Boston Brace was more successful than the Milwaukee brace irrespective of initial curve magnitude and skeletal maturity (Montgomery and Willner,1989) because the use of the Milwaukee brace resulted in scoliotic curve stabilization but not correction. The Milwaukee CTLSO can be recommended in cases with a single lumbar or thoracolumbar curve. In addition, a study found the Milwaukee CTLSO to be significantly more successful than all other types of orthoses and the Charleston Brace to be significantly less successful than the Milwaukee CTLSO (Rowe, Bernstein et al., 1997) Comparing the Boston Brace with the Charleston Bending Brace A study indicated that the Boston brace is more effective than the Charleston brace, both in preventing curve progression and in avoiding the need for surgery. These findings were most notable for patients with curves of 36-45, in whom 83% of those treated with a Charleston brace had a curve progression of more than 5, compared with 43% of those treated with the Boston brace. When given the choice between these two orthoses in the treatment of adolescent idiopathic scoliosis, the authors recommend use of the Boston brace. The Charleston brace should be considered only in the treatment of smaller single thoracolumbar or single lumbar curves (Katz, Richards et al., 1997) Other literature on the biomechanics of spinal orthotics. A study by Odermatt, Mathieu et al. (2003) indicated that when a brace is used to correct a spinal deviation, patients may seek to ease the discomfort from the pressure 17

35 exerted by the orthosis by actively recruiting specific trunk muscles. Brace-induced increases in EMG activity were significant in the individual measurements. Increases were greater in the lumbar area, especially on the convex side of the secondary (lumbar) curve. These results thus suggest that immediately following the application of a brace, significant muscular responses can be observed in some patients. Therefore, it can be concluded that muscles will control and affect the successful correction of a curvature of the spine. Mac-Thiong, Petit et al. (2004) conducted a prospective study intended to evaluate the association between strap tensions and brace interface forces in the treatment of adolescent idiopathic scoliosis using the Boston brace system. The brace interface forces and the corresponding effective areas increased along with the strap tension for all patients. For patients with a single right thoracic curve, the interface pressure tended to increase with increasing strap tension. However, most of this increase occurred between 20 N and 40 N of strap tension, with only a slight increase or even a decrease in interface pressures between 40 N and 60 N. Clinicians should ensure that the prescribed strap tension does not cause excessive skin pressure or affect compliance with use of a brace The faults of bracing treatments Brace treatments do not generally correct scoliosis, but they can prevent further progression, so bracing has a holding effect (Willers, 1993). In the published studies on this topic, brace treatments have been considered a failure if the patient subsequently had operative stabilization or if the curve progressed five degrees or more compared with the curve before the bracing (Price, Scott et al., 1990). In addition, a study of 25 patients that investigated the long-term effect of the Boston brace found that the Boston brace did not improve scoliosis curvature but did prevent progression of vertebral rotation, translation, 18

36 rib hump, and increased in the Cobb angle in idiopathic scoliosis (Willers, Normelli et al., 1993). Some negative effects of bracing treatments can be observed after long periods of use, such as muscle atrophy and possible weakness, joint contracture after a period of immobilization, psychological dependence or emotional disorders, hypermobility in areas above or below the immobilized areas, respiratory difficulty due to compression, discomfort and poor posture or appearance The effect of therapy exercise on scoliosis So some scholars, particularly orthotists, assume that the treatment succeeds partly because the patient s spinal column on the convex side, under pressure, evokes irritation and causes discomfort in the soft tissue, which induces the patient to contract the muscle actively in order to avoid or relieve the pressure by movement inside the brace. Final, the spine column will remain in a straighter posture as an indirect result. This aspect can be inferred from Daniel s (Daniel, 2003) research paper comparing the influence of the brace on IS patients superficial level back muscle groups. The EMG signals of the back muscles differed obviously under the brace function. Namely, under the external force function, the EMG of the back muscle group on the superficial level shows that the muscle activity under the brace pressure increases distinctively comparing to that without the brace on. Medical care personnel, especially physiotherapists, have suggested that the gradual imbalanced muscle tones on both sides of the spine column are connected to the deterioration of the spinal curve. Thus, therapeutic exercise can be used on a scoliosis patient whose Cobb angle is less than 25 degrees to prevent and correct the curve and to maintain good posture. In early times, the effect of the exercise therapy on scoliosis was denied by doctors 19

37 (Stone, 1979), due to the fact that in outpatient treatments, they asked the patient to do the prescribed movement during home and did measurements on the angle variations when the patients came back to the clinic. Yet, through inspection, these studies had no evidence of rigorous clinical supervision and experiments provided in research papers during the research process. Therefore, this research, under the supervision and guidance of some physiotherapists, the clinical research was done again using the therapeutic exercise conducted on these scoliosis patients. The outcome indicated that therapeutic exercise has distinctive effects in controlling a Cobb angle of less than 25 degrees. Some clinical experiences show that, among all the non-invasive treatments, therapeutic exercise involving active muscle contraction has positive effects both on the reduction and prevention of the scoliosis curve. Furthermore, it was found in a review that non-invasive treatments for preventing the spinal curve from progression include passive brace treatment and the active therapeutic exercise. (Willner, 1984) The effect of biofeedback on scoliosis It was shown research by Wong (Wong, 2001), which involved the use of a biofeedback machine to remind the patient to stay in the correct posture, that biofeedback treatment cannot reduce the patient s Cobb angle, but, in the meantime, it did not produce deterioration. This indicates that for 18 months the patient did not undertake the external force provided by the brace to prevent deterioration. During this period of time, only autonomous postural maintenance was adopted to keep the original angle. This also shows that staying in a correct posture and using appropriate muscle functions can result in reduction in the spinal curve. It is concluded from this research that a feedback approach has a better effect on a patient s coordination of body movement than the brace approach and it does not result in atrophy or muscle weakness. The shortcoming is that it can only be 20

38 applied to a patient with a scoliosis Cobb angle within 25 degrees, and it does not reduce the angle like the brace does. In addition, the approach of correcting scoliosis by using a biofeedback machine can also be applied to clinical treatment approaches. 21

39 1.4 Research objective In most traditional braces, however, a three-point compression system is the main method that is used to correct scoliosis (Bowker, 1993) (Chase, Pearcy, Bader et al., 1993). (Figure 1.12) Because of the principles of biomechanics, counterforce (F2) can be used to oppose the apex of the vertebra which gradually deviates from the midline on any curvature of the spine in the frontal plane and simultaneously gives the same direction and size of the fixed force (F1) on the upper and lower ends of the curve on the concave side (Lindahl and Raeder, 1962). Unfortunately, traditional braces with three-point compression systems cover only the frontal plane and not the sagittal plane, and the inner pads are fixed and non-adjustable. Figure 1.12 The three-point compression system used in a brace design. The two F1 force are supporting forces, while the F2 is the push force. 22

40 The Boston brace was therefore developed, and three-point compression has been used to treat idiopathic scoliosis for a long time (Perie, Aubin et al., 2003). In order to obtain suitable correction and to control the progression of the curvature of the spine, the brace needs to be worn for more than 23 hours per day until the bone matures. During correction, the source of the external force is provided mainly from a pressure pad in the liner of the brace, but there are the following complications: sore back muscles, pain, muscle weakness or atrophy, and fault proprioception, among others (Wynarsky and Schultz, 1989). In addition, the spinal curve is often restored to its original shape, or there is only a small correction after the patient removes the brace, based on clinical observation using x-ray films. In order to improve the faults mentioned above, several new braces or orthotics, such as the TriaC brace (Veldhuizen, Cheung et al., 2002), and audio biofeedback (Wong, Mak et al., 2001), among others, were recently developed and have been used for AIS patients. The concept and principle of these new designs are different from those of traditional braces, and their materials include an electronic device or an elastomer. Finally, studies of these new designs have only reported that the spinal curve development and complications from the brace were eliminated, but the Cobb angle was not decreased (D'Amato, Griggs et al., 2001). In accordance with these investigations, these faults in bracing treatments can be produced from the tightly worn pressure pads and the fact that the pad material is more solid than the soft tissue of the trunk. Therefore, determining a method by which to increase the effectiveness and the prevention of the faults of the pressure pad inside the brace is the purpose of this study. The 3D airbag device proposed herein can be applied by using a number of adjustable pneumatic airbags to replace the fixed pressure pad inside the Boston brace, which is then dominated by the 3D Airbag brace. This design has a multi-focal point on the correct forces which can be adjusted and modulated by the size 23

41 and location of the airbag so as to make a significant difference and improve the faults of traditional braces. Finally, the effect of correction between different types of braces can be compared in the general clinical research from a literature review of AIS, and the biomechanics of spinal orthotics mainly emphasizes that successful correction depends on the accurate application of adequate force in the correct position. However, studies have pointed out that the back muscles can be affected properly in the case of AIS during the wearing of a brace due to the fact that in-brace exercise can occur as a result of an uncomfortable pressure between the skin and the brace on the back muscles around the spine. Therefore, the objective of this study is to survey the effects of the 3D Airbag brace used for idiopathic scoliosis with replacement of the pressure pad from the traditional brace with an airbag, and to research the effect of exercise at Cobb angle when which affect the effects of treatment with AIS using the 3D Airbag brace. It is hoped that the results of this study can be applied to increase the effects of clinical treatment of AIS. 24

42 CHAPTER 2 Methods and Materials In order to identify the effects of the 3D Airbag brace on AIS patients, the Cobb angle of the scoliosis can be detected by X-rays. In addition to this, with regard to the condition of the skin-orthotic interface and the muscle activity on the paravertebral between the brace and the trunk, this study uses four parameters, including pressure, contact area, external force, and EMG signal, combined with seven exercises/postures exhibited in the results from the Tactilus pressure mat and the surface EMG instrument inside the 3D Airbag brace. The Cobb angle to be calculated on the scoliosis patient can be decreased or arrested, and a successful bracing treatment can be determined. In terms of any braces, however, it is important that an amount of external force can be accurately applied to the key points and specific areas of the spinal curve from the pressure pad. Moreover, different trunk postures or exercises also influence the effects of the skin-orthotic interface, so the correction resulting from the brace can be interfered with by these factors. Therefore, the experiment conducted in this study consisted of three parts. The first part is intended to compare variations in the Cobb angle values before and after treatment, and the second part is intended to detect changes in the amount and areas of correct pressure by the pressure pad under different conditions. Ultimately, the third part is to compare the differences in the effects of the in-brace exercise method for the back muscles activated by the EMG signal. 25

43 2.1 The manufacturing procedure for the 3D Airbag brace The correct principle of the 3D Airbag brace Because idiopathic scoliosis is a complex 3D structural deformity of the spinal vertebra, except for visible lateral shifting of the curve of the spine, axial rotation of the vertebra on the curve is the main cause (Figure 2.1). However, traditional braces used to administer the correct force on the curve have been based mainly on the principle of a three-point compression system of mechanics intended to prop up the declining region at several positions, but they are not focused on the integral spine or the vertebrae. So, according to investigation, many of the results of brace treatments only stop the aggravation of the scoliosis curve, and a few patients still need surgery because their Cobb angle is greater than 40 degrees. Therefore, in order to increase the rate of the effective treatment, a 3D Airbag brace has been determined to be more tailor-made to the patient as compared to a traditional brace. Figure 2.1 Correction moments for rotated vertebra; Fr is the rotational force couple on the vertebrae; Fa and Fp are the antagonistic forces working on the anterior and posterior side of the trunk. 26

44 2.1.2 The manufacturing process for the brace First, the shape and location of the scoliosis are confirmed and shown by a standing AP X-ray film of the spinal vertebrae before making the brace. Then, a model is taken and modified along the trunk of the patient using a plaster cast while the patient is standing with an erect trunk. Next, the negative mold from the trunk is cautiously removed, and the positive mold is then transformed after filling the negative mold with gypsum. When the positive model is covered with about 3mm of thick plastic that can be warmed up in order to be softened, the preliminary shell of the brace can be made after the plastic has become cold and stiff (Figure 2.2). Unlike traditional braces, the inner surface of the preliminary shell is even and smooth, and the rim of the brace is not trimmed except near the breast area. (a) (b) Figure 2.2 Original brace (a) anterior view (b) posterior view After the primary shell is attached to the padlock in the back of the brace, the initial brace can be worn and modified until the patient gets used to the feeling of the compaction sensations and the restricted movement of the trunk. Before the airbag that is the main source of correct force is assembled inside the special position in the primary brace, an 27

45 orthotist needs to decide the site and area of the airbag in accordance with the principle of the three-point compression system in the frontal and sagittal planes using a standing AP X-ray film of the scoliosis, and then a small gas hole is excavated that can be used to inject air into the airbag from the outside. After all modular components are assembled and orientated, the physician will inject the appropriate amount of air into the pneumatic airbags (Figure 2.3). After the patient is accustomed to the pressure, more air is pumped in again every two weeks to the point that the patient can tolerate it. To ensure that the patient will fit in the brace comfortably, if the patient ever feels discomfort, air pressure can always be adjusted or reduced. (a) (b) Figure 2.3 The airbag component (a) flat shape (b) after filled with air In other words, in the shape of the 3D Airbag brace, the upper and lower ends of the brace usually may begin from the T3 or T7 level and follow to the GT level of the femoral head. The amount and seat of the airbag, however, is developed according to the degree of the Cobb angle and level of rotation of the vertebra so as to increase or decrease and adjust the size and exert the correct force (Figure 2.4). 28

46 (a) (b) (c) (d) Figure 2.4 (a) Brace accomplished from anterior view (b) superior view. (c) The subject with her brace (d) the X-ray film with brace 29

47 2.2 Subject information A total of 20 subjects (18 females, 2 males) with IS were prescribed with the 3D Airbag brace. Due to the limited number of subjects, no specific criterion was employed for subject selection, and all subjects were included in the follow-up study. The ages of the subjects ranged from 6 to 16 years old (11.8±2.8 years) at the beginning of the treatment. Their Risser signs ranged from zero to four. Twelve subjects had one spinal curve (four in the thoracic region and eight in the lumbar region). The other eight subjects had double curves (in both the thoracic and lumbar regions). The twelve thoracic Cobb angles ranged from 18 to 48 degrees (37.3 ± 10.6 ), measured with Anterior-Posterior (AP) X-rays. The sixteen lumbar Cobb angles ranged from 20 to 40 degrees (30.1 ± 7.2 ). The follow up period for the 3D Airbag brace treatment was 4 to 24 months (11.5±6.6 months). Standing AP X-rays of each subject were taken for Cobb angle measurement every three months during the follow up period. This is a standard procedure and not an extra treatment for the brace treatment. Detailed data for these subjects is listed in Table 2.1 and Table

48 Table 2.1: Data for subjects with thoracic curve Risser No.* Age Sex sign Convex side Follow (month) Cobb angle Cobb before after angle 1 6 f 0 Right f 2 Right m 3 Right f 2 Right m 4 Left f 0 Left f 0 Right f 3 Right f 3 Right f 3 Right f 0 Right f 0 Right *Subjects 1 to 8 have both thoracic and lumbar curves and are also listed in Table

49 Table 2.2: Data of subjects with lumbar curve Risser No.* Age Sex sign Convex side Follow (month) Cobb angle Cobb before after angle 1 6 f 0 left f 2 left m 3 left f 2 left f 4 right f 0 right f 0 left f 3 left m 3 right f 0 left f 3 left f 3 right f 0 right f 0 right f 0 right f 2 right *Subjects 1 to 8 have both thoracic and lumbar curves and are also listed in Table

50 2.3 Material/instruction setup Measurement pressure on the skin-orthotic interface Each subject had his/her own 3D Airbag brace to participate in the study and treatment. In order to measure the soft tissue able to endure the area of contact pressure, a commercial pressure mat was placed between the brace and the trunk to measure the skin-orthotic interface. A total of two pieces of pressure mat were applied to the experimental group, and each mat measured 20 x 20 cm2. The mat used was the Tactilus pressure mat (Figure 2.5) (Sensor Products Inc.; Madison, New Jersey) that includes 256 piezoelectric sensors, and the size of each sensor is 2.5 cm2. The sensor specifications were as follows: a capacity of N/cm2, accuracy of ± 10 percent, repeatability of ±1.7 percent, hysteresis of ±3 percent, special resolution of 12.5 mm, sample rate of 30 Hz, and nonlinearity of ±1.8 percent. The creep and hysteresis effects in the sensor could be automatically corrected by the Tactilus software. Figure 2.5 Tactilus pressure mat (Sensor Products Inc.; Madison, New Jersey) 33

51 2.3.2 Measurement the muscle activity using an EMG An eight-channel wireless EMG (Noraxon, Telemyo 2400T) with paper-thin surface electrodes (Medi Trace 100, Canada, Ltd.) were used in this study (Figure 2.6), as this can reduce the pressure when wearing a brace. In addition, a 2D Goniometer (biosensor, back SG150) was used to track the patients spinal angles in different postures. The equipment set up contained six bipolar surface EMGs connected to channels 1to 6 of the host machine (bandpass: Hz, sampling size: 3000Hz, with a gain of 2). In addition, channels 7 and 8 of the host machine were connected to the X-axis and Y-axis of the 2D Goniometry to receive the angle of the spine and the surface EMG signals simultaneously under different postures. Figure 2.6 The EMG instrument (Telemyo 2400T, Noraxon Inc., USA) 34

52 2.4 Data collection procedure Data collection for this study was divided into three parts. The first parts was the data derived from the correction effects of the 3D Airbag brace, which was collected and observed for 4 to 24 months (11.5 ± 6.6). The second part, which was used to detect the variance in the pressures at the skin-orthotic interface during different postures/actions, was the amount of contact pressure from the pressure mat. The third part, which was intended to compare the differences in the erector spinae activity during the in-brace exercise, was measured using the EMG signal from the erector spinae. The order of presentation was as follows: Before the patient was able to correct the scoliosis using the 3D Airbag brace, the spine needed to be softened. Then, according to the above-mentioned method, a personal brace was created, and the difference in the procedures for the Cobb angle without the brace as observed from a standing AP x-ray film between pre-correction and post-correction was observed and recorded every 3 months. After all children and their parents consented to participate in this study, the center line of the Goniometer was first set in the apex with the curved side, and to stick two excellent ends suddenly along the spine separately. Secondly, stick EMG electrode. Then, the pressure mat could cover the airbags that had been filled with air, and all subjects wore a tight brace with measurement instructions. The average pressure, contact area, and external force on the skin-orthotic interface were obtained via the pressure mat instrument, and the muscle activities of the erector spinae were simultaneously obtained from the EMG instrument (Figure 2.7). Before the experiment could proceed, the subject first had to practice and understand the in-brace exercise for trunk movement and how to maintain the posture of the trunk as 35

53 follows: upright positioning, flexion, extension, bilateral side bending, and bilateral axial rotation inside the brace (Figure 2.8). Then the subjects were asked to accomplish actual exercises, and three parametrics were simultaneously collected. During the study, in order to be measured for approximately 1 hour per subject, each in-brace exercise had to be completed 5 times; the position had to be held for 5 seconds, and then the subject then reverted to the upright position for a 5-second rest. The purpose of this experiment was to detect the effects of the 3D Airbag brace among the different in-brace exercises. Figure 2.7 the coil of the 2D Goniometer was first placed on the apex of the curve, and then the sensors were fixed on both ends of the upper and lower spine. The surface electrode pads, connected to channels 1to 6, were attached to the skin on both sides of the spine along the three parts of the 2D Goniometer. 36

54 Figure Upright posture Figure Trunk flexion Figure Trunk extension Figure Left side bending 37

55 Figure Right side bending Figure Right axial rotation 38

56 2.5 Data analysis Dividing into three parts can be treatment after data collected. Finally, the statistical analyses were conducted in the study using SPSS statistics The effect of correction from calculable Cobb angle The Cobb angle was measured from the X-ray of the scoliosis subject, and the results of correction were calculated both before and after treatment. This effect of correction was divided into two parts for analysis: A comparison of the results from the mean differences and alterations to the Cobb angle without the brace considering the curvatures of both the thoracic and the lumbar areas using the paired t-test and the p value of 0.05 was selected to justify a significant difference. A comparison of the results from the mean differences in the Cobb angle without the brace between pre-correction and post-correction using the paired t-test method was used for the statistical analyses to compare the Cobb angle before and after brace treatment. The p value of 0.05 was selected to justify a significant difference The analysis of three parameters The three parameters, average pressure, contact area, and contact force, were measured using the Tactilus pressure mat, and the interface pressure measurements were averaged to access the influence of posture changes. Three parameters were calculated by the Tactilus software. Finally, the three parameters could be normalized in order to determine the differences between each posture, and the average pressure parameters could be compared with strap tensions suggested in the literature for each in-brace exercise. 39

57 2.5.3 The surface EMG treatment and analysis With regard to the surface EMG signals, the raw ECG signals were first detected using a MyoResearch XP EMG produced by Noraxon. The EMG RMS values for each posture from the six channels were obtained through post-treatment procedures. The mean of the three EMG RMS values was set as the concave group on the concave side, and the mean of the three EMGs on the convex side was set as the convex group. The data analysis process was divided into three parts, and was carried out using the SPSS Statistics 17.0 software package. In the first place, the influence of the brace on muscle activity was analyzed, with paired samples t-tests being used to examine if there were any significant differences between in-brace and out-of-brace exercise under the same posture. Afterwards, the mean of the EMG RMS of the seven postures was then tested through correlated sample one-way ANOVA of repeated measures to analyze the muscle activity of each posture during in-brace and out-of-brace exercise. Because the muscle groups on both sides of the spines of scoliosis patients have unequal tension, the third part of the data analysis examined whether the two muscle groups showed any significant differences due to the interactions of the brace and postures. The ratio of the EMG RMS on the concave and convex sides was thus obtained. If this ratio is larger or smaller than 1, this means the muscle activity on both sides is significantly different. Finally, the results with regard to how the muscle activity on both sides of the spine is influenced during in-brace and out-of-brace exercise were compared through a single sample means test. This approach was used to examine if the brace changes the muscle activity on both sides of the spine under different postural conditions. 40

58 CHAPTER 3 Results This study had a sample of 20 scoliosis patients who wore the brace, and further progression of the scoliosis did not occur in anyone. In order to understand the variations in the correction between the thoracic and lumbar regions, this study was divided into two groups (thoracic and lumbar curvatures), resulting in a total of 28 curvatures. During the research, 5 subjects dropped out of the EMG and pressure data measurement. Therefore, only the data for 15 subjects was analyzed. 41

59 3.1 The correct effect for the 3D Airbag brace The Cobb angles before and after the follow up period for each subject are listed in the last two columns of Table 3.1 and 3.2. During the follow up, all subjects presented Cobb angle reduction except in the case of one thoracic curve, subject 7, as shown in Table 2.1. It is clear from the Cobb angle measurements that the spinal curve improved notably with the use of the airbag brace treatment (Figure 3.1). Table 3.1 shows the current Cobb angle after removal of the 3D Airbag brace, and it can be seen that there was a significant difference (p <0.05) between the results before (33.1 ± 9.4) and after (21.8 ± 10.3) the correction. In addition to this, after the lumbar and thoracic curves were distinguished from the 28 curves, the correction effect of the Cobb angle at each curve was separated. The results show that the lumbar region was corrected better than the thoracic region and that all subjects experienced a significant difference after treatment (thoracic: 37.3 and 27.3; lumbar: 30.1 and 17.7) (Table 3.2). Figure 3.1 (a) The AP X-ray films before the follow up period of one subject without the brace. (b) The AP X-ray films after the follow up of the same subject without the brace. 42

60 Table 3.1. The differences in the Cobb angle after removal of the brace before and after correction N= 20 (boys =2, girls =18) Treatment: months (15±2.0) Curve type: (double curve = 8, single curve = 12) Cobb angle Before treatment Cobb angle After treatment p value N=28 (Thoracic curve 33.1 ± ±10.3 t = p<0.05 +Lumbar curve) Table 3.2 Statistical outcomes of airbag brace treatment at thoracic and lumbar curves. Cobb angle before treatment Cobb angle after treatment p value thoracic curve 37.3 ± ±10.1 t = 5.77 (n= 12) (18~48 degree) (8~38 degree) p<0.05 lumbar curve 30.1 ± ± 8.6 t = (n= 16) (20~40 degree) (0~30 degree) p<0.05 p value t= 2.03, p>0.05 t= 2.66, p<0.05 Statistically, for all subjects, the curves at both the thoracic and lumbar regions exhibited a significant reduction during the follow up period, as shown in Table 3.1. The Cobb angle at the thoracic region reduced from 37.3 ±10.6 to 27.3 ±10.1, with a mean decrease of 9.9 ± 5.9. The Cobb angle at the lumbar region decreased from 30.1 ± 6.9 to 17.7 ± 8.6, with a mean reduction of 12.4 ± 4.9. The correction effect at the lumbar curve 43

61 is significantly better than that at thoracic curve even though there is no significant difference between the Cobb angles of the thoracic and lumbar regions before treatment. However, if the differences in the Cobb angles between the thoracic and lumbar curves are separated before and after treatment, the results indicate no significant difference before treatment (37.3 and 30.1 p>0.05), but show significant differences after treatment (27.3 and 17.7, p<0.05) (Table 3.2). A comparison of the treatment effects at both the lumbar and thoracic regions revealed the correction to be the same as that of traditional braces, and the lumbar region was more improved than the thoracic region. 44

62 3.2 Interface pressure, contact area and force The average pressure, contact area, and contact force of the brace during the seven body postures (upright plus the six exercises) from the 15 subject are listed in Figure 3.2 and Table 3.3. Quantitatively, the average contact pressure, contact area, and contact force in the upright position were 8.91±0.74 kpa, 379.1±16.5 cm2, and 351.4±42.0 N, respectively. The contact pressures during flexion and lateral bending to the convex side were 8.22±0.55 kpa and 8.30±0.58 kpa, respectively. These two exercises were identified with maximum reduction of contact pressure when compared with the upright posture. Correspondingly, the contact force during lateral bending to the convex side and flexion were 315.8±32.7 N and 319.6±27.6 N, respectively, and the maximum reduction of contact force was also identified in these two exercises. However, using the upright posture as the base line, the changes of these measured parameters were all less than 10%, as shown in the normalized values in Table 3.4. No significant difference could be identified. This should be due to the constraint from the brace, which limited the range of motion for all exercises. Figure Upright (Average pressure: 8.2Kpa, Contact Area: cm2, Force: 319 N) 45

63 Figure Flexion (Average pressure: 10.7 Kpa, Contact Area: cm2, Force: N) Figure Extension (Average pressure: 9.2 Kpa, Contact Area: cm2, Force: N) Figure Bending to the concave side (Pressure: 9.4Kpa, Contact Area: cm2, Force: 336.7N) 46

64 Figure Bending to the convex side (Pressure: 9.3 Kpa, Area: 397 cm2, Force: 367.2N) Figure Rotation to the concave side (Pressure: 7.5 Kpa, Area: cm2, Force: 276.7N) Figure Rotation to the convex side (Pressure: 7.4 Kpa, Area: cm2 Force: 310 N) 47

65 Table 3.3 The measured interface parameter values during exercise. Pressure (Kpa) Contact Area (cm2) Contact Force (N) Mean ± S.E norm* Mean ± S.E norm* Mean ± S.E norm* upright 8.91± ± ± flexion 8.22± ± ± extension 8.52± ± ± LB cav1 8.75± ± ± LB cvx2 8.30± ± ± Rot cav3 8.87± ± ± Rot cvx4 8.61± ± ± *Using upright values to normalize the outcome 1. Tend for lateral bending (LB) to the concave side 2. Lateral bending to the convex side 3. Rotation (Rot) to the concave side 4. Rotation to the convex side 48

66 3.3 muscle activity on superficial back muscle group (Erector Spinae) The EMG RMS values of the fifteen subjects after all postural measurements are shown in Figure 3.3 and Table 3.4. All the EMG values of No. 12 are larger than those of the other subjects, except for Flex and BFlex. It can be seen in the figure that during the out-of-brace exercise, the value of trunk rotation to the convex side without the brace (RTV; 25.83±4.7) is the largest, while the value of trunk flexion without the brace (Flex; 13.71±2.2) is the smallest. In contrast, during the in-brace exercise, the value of the trunk flexion with the brace (BFlex; 34.04±13.6) is the largest, while that of trunk lateral bending to the convex side with the brace (BSTV; 16.51±9.0) is the smallest. Figure EMG Row data for the extension without the brace Figure EMG RMS data for the extension without the brace 49

67 Table 3.4 The EMG RMS of in- and out-of-brace exercises with difference postures NO sex RT Flex Ext STC STV RTC RTV BRT BFlex BExt BSTC BSTV BRTC BRTV 1 female female female female male female female female female female female female female female female Mean ± 27.82± ± SD ±4.7 ±2.2 ±4.7 ±3.6 ±3.6 ±3.4 ±4.7 ±23.0 ± 13.6 ± 23.2 ± 17.5 ± RT: upright trunk, Flex: flexion trunk, Ext: extension trunk, STC: side bending to concave side, STV: side bending to convex side, RTC: rotating to concave side, RTV: rotating to convex side; BRT, BFlex, BExt, BSTC, BSTV, BRTC and BRTV are same as the above activities in-brace. 50

68 3.3.1 Influence of using a brace on muscle activity during different exercises The results of the statistical analysis show a confidence interval (C.I) of 95% and a p value of <0.05 when the influence of wearing a brace on muscle activity under the same postural conditions is compared through paired samples t-tests. Table 3.5 shows that the EMG values of four movements (trunk upright, trunk flexion, trunk extension and trunk rotation to the concave side) under in-brace conditions are significantly larger than those seen under out-of-brace conditions although this is not true for the other three movements, namely trunk lateral bending to the concave side, trunk lateral bending to the convex side and trunk rotation to the convex side. This indicates that the brace stimulates more muscle activity during most actions. Table 3.5 The paired samples t- tests to test differences between in-brace and out-of-brace exercises under the same postural conditions. BRT-RT BFlex-Flex BExt- Ext BSTC- STC BSTV- STV BRTC- RTC BRTV- RTV Mean ± SD 5.11± ± ± ± ± ± ±3.2 t value 2.31* 6.44* 2.37* * 0.62 RT: upright trunk, Flex: flexion trunk, Ext: extension trunk, STC: side bending to the concave side, STV: side bending to the convex side, RTC: rotating to the concave side, RTV: rotating to the convex side; BRT, BFlex, BExt, BSTC, BSTV, BRTC and BRTV are same as the above activities in-brace. 51

69 3.3.2 The difference between muscle activity during different exercises under the same conditions The significance of the EMG values obtained for the different exercises is tested by a correlated sample one-way ANOVA of repeated measures (C.I = 95% and p value < 0.05). In Table 3.6, the results of the comparison of all the out-brace exercise are non-significant (F(6,48) = and p =0.082 >.05). The results of the test indicate that there are no significant differences among the muscle activities related to various exercises in the out-of-brace condition. Although the differences among the out-of-brace exercises are not significant, the muscle activity associated with trunk flexion (Flex) is the smallest of the pairwise comparisons, smaller than that of the trunk rotation to the concave side (RTC) and trunk extension (Ext). This indicates that the back muscles of most of the subjects were less active during these postures. Furthermore, the EMG value for RTV is the greatest of all the postures, and the difference is significant when compared with the RTC (8.73±3.3, p<0.05), which indicates that RTV activates the muscles more easily than RTC. In Table 3.7, the comparisons of all the in-brace exercise are significant (F(6,48) = and p =0.011 <.05). The results of the test indicate that there are significant differences among the muscle activities involved in various postures when wearing a brace. The EMG value of BFlex is the largest, based on the pairwise comparisons, larger than that of BExt. The EMG values of BSTV and BSTC are the smallest, and there are significant differences among the BFlex, BExt, BRTC and BRTV, which indicates the muscle activities of these two postures when wearing a brace are the poorest. 52

70 Table 3.6 Correlated sample one-way ANOVA of repeated measures to analyze out-of-brace exercises. RT Flex Ext STC STV RTC RTV RT ± ± ± ± ± ±4.1 Flex 5.63± ± ± ± ± ±5.7 Ext 1.55± ± ± ± ± ±4.3 STC -1.81± ± ± ± ± ±4.0 STV -1.13± ± ± ± ± ±4.1 RTC 2.24±3-3.39± ± ± ± ±3.3* RTV -6.49± ± ± ± ± ±3.3* - RT: Trunk upright posture, Flex: Trunk anterior flexion posture, Ext: Trunk posterior extension, STC: Tend for lateral bending (LB) to the concave side, STV: Lateral bending to the convex side, RTC: Rotation (Rot) to the concave side, RTV: Rotation to the convex side Table 3.7 Correlated sample one-way ANOVA of repeated measures to analyze in-brace exercises. BRT BFlex BExt BSTC BSTV BRTC BRTV BRT ± ± ± ± ± ±5.0 BFlex -9.59± ± ±6.2* ±4.5* -8.70± ±6.6 BExt -2.43± ± ±2.5* ±4.1* -1.54± ±4.3 BSTC 3.91± ±6.2* 6.34±2.5* ± ± ±3.4* BSTV 7.95± ±4.5* 10.37±4.1* 4.04± ±2.5* 11.31±3.2* BRTC -0.88± ± ± ± ±2.5* ±2.5 BRTV -3.36± ± ± ±3.4* ±3.2* -2.48±2.5 - BRT: Trunk upright posture with brace, BFlex: Trunk anterior flexion posture with brace, BExt: Trunk posterior extension with brace, BSTC: Tend for lateral, ending (LB) to the concave side with brace, BSTV: Lateral bending to the convex side with brace, BRTC: Rotation (Rot) to the concave side with brace, BRTV: Rotation to the convex side with brace 53

71 3.3.3 The influence of the brace on the bilateral muscle activity of the spine The muscles on both sides of the spine have an imbalanced length-tension relationship among scoliosis patients. The paraspinal muscle on the concave side is shorter and stronger than the same muscle on the convex side, and this interferes with normal movement patterns in daily life. This study thus examines the variations in back muscle activity when wearing a brace while carrying out various exercises and postures. In order to investigate this, the EMG values on the convex side during different movements are first divided by the EMG values on the concave side. When the ratio is >1, the muscle activity on the convex side is greater than that on the concave side. Next, single sample means tests (value =1) are used to conduct the statistical analysis (C.I = 95%, p value <0.05). When the ratio of both sides tested by the value (=1) is significant (p<0.05), this indicates that the muscle activity on the convex side during a certain posture is significantly larger than that on the concave side. All the EMG value ratios on both sides of the spine in the out-of-brace exercise condition are shown in Table 5a, among which the RTV ratio is the largest (4.21 ±0.9), where that of Ext is the smallest (0.90 ±0.1). Of all the ratios, only that for RTV is significantly different (t (14) = 3.46, p < 0.05) under the single sample means test (value =1). All the EMG value ratios on both sides of the spine in the in-brace exercise condition are shown in 5b. The largest ratio is that for BRTV (2.49 ±0.6), and the smallest is for BRTC (0.81 ±0.2). Of all the ratios, those for both BSTV (t(14) = 2.46, p <0.05) and BRTV (t(14) = 2.71, p <0.05) are significantly different (t(14) = 3.46, p < 0.05) under the single sample means test (value =1). 54

72 Table 3.8 The EMG value ratios on both sides of the spine in the out-of-brace exercise condition. NO RTVexdCav FlexVexdCav ExtVexdCav STCVexdCav STVVexdCav RTCVexdCav RTVVexdCav Mean ±SE 1.27 ± ± ± ± ± ± ±0.9 value=1 t= 1.66 t= 0.51 t=-1.38 t=1.02 t=1.84 t=0.3 t=3.46* RT: Trunk upright posture, Flex: Trunk anterior flexion posture, Ext: Trunk posterior extension, STC: Tend for lateral bending (LB) to the concave side, STV: Lateral bending to the convex side, RTC: Rotation (Rot) to the concave side, RTV: Rotation to the convex side, VexdCav: convex side divided by the concave side 55

73 Table 3.9 The EMG value ratios on both sides of the spine in the within-brace exercise. NO BRTVexdCav BFlexVexdCav BExtVexdCav BSTCVexdCav BSTVVexdCav BRTCVexdCav BRTVVexdCav Mean ±SE 1.03 ± ± ± ± ± ± ±0.6 value=1 t=0.38 t=1.16 t=0.79 t=-0.08 t=2.46* t=-1.18 t=2.71* BRT: Trunk upright posture with brace, BFlex: Trunk anterior flexion posture with brace, BExt: Trunk posterior extension with brace, BSTC: Tend for lateral, ending (LB) to the concave side with brace, BSTV: Lateral bending to the convex side with brace, BRTC: Rotation (Rot) to the concave side with brace, BRTV: Rotation to the convex side with brace, VexdCav: convex side divided by the concave side 56

74 CHAPTER 4 Discussion Braces have been applied in this context with the exception of use for the protection and support of unstable or injured vertebrae. Correcting deformities of the spine is also the main purpose because scoliosis is defined as the spine deviating from the posterior midline of the trunk toward the lateral curve so that treatment applying the correct force exerted from an external device must be used. Due to the fact that braces are able to provide the external force needed to correct for and avoid the shifting of the vertebrae by constraining the trunk and that they use the principle of a three-point compression system, which offers a corrective mechanism, bending movements can be reduced and deforming deterioration of the spine can be prevented in the frontal plane through the use of dynamic orthotics. Therefore, braces are the most effective non-surgical treatment for correcting and preventing scoliosis. However, some faults still exist with traditional braces, so improving these defects is the reason why current spinal orthotics is continuously being modified. In order to adapt the form and structure to children s periods of growth and development, the brace has to be remodified and remodeled often. Then, the external forces of the brace can be applied to the spine from pressure of the fixation pad at specific positions using a posterior tension strap. If the correct force cannot be exerted to push the vertebra towards the midline of the trunk, traditional braces will only provide a supporting function to avoid progressive development of the spinal curve. Also, when the hard pads continuously press on the soft tissue of the trunk, pain can make the patient not want to wear the brace. 57

75 4.1 The mechanism and advantages of the 3D Airbag brace for correcting IS The 3D Airbag brace uses a modular and movable airbag to mitigate the pressure from fixed and hard pads, which have the following advantages; first of all, in traditional pad braces, the correction force is difficult to monitor and adjust. In general the push force of the pad comes indirectly from tension in the brace straps (Mac-Thiong, 2004). It is difficult to effectively control the correction force to further push the vertebra into the midline of the trunk if the curve reduction is achieved. On the contrary, an airbag brace consists of multiple airbags used to adapt to or adjust the variables in the form or structure of the trunk by increasing or decreasing the number of airbags. This brace has the airbag installed in a special position between the orthotic and the patient s trunk, and the correct forces consist of an intra-correction force which pushes the vertebra toward the midline of the trunk with suitable pressure from the airbags. The adjustable intra-correction force is different from the non-adjustable force of a traditional brace with regard to the method of offsetting the force. The extra correctional force of a general brace can be only provided from the tension of straps behind the brace during the tightening of the straps. According to a study (Mac-Thiong, Petit et al., 2004; Wong, Mak et al., 2000), the mean pressure of the pressure pads is approximately 7.09 kpa; the mean tension of the straps is approximately 26.8 N, and the correlation coefficient of the strap tensions and pad pressure is significant, so the correct force of a traditional brace can be affected by the tension of the straps. Although the shell of the airbag brace also creates a firm boundary to provide a base which transforms the pressure into a push force to move the vertebra, the difference is that the excess pressure is increased by putting air into the airbag. In other words, the non-adjustable force 58

76 of a traditional brace directly provides a static pressure from the outside tension of the strap, and the intra-correctional force of the airbag brace results in variable pressure from the airbag between the brace and the trunk. X-ray photos of some subjects wearing the brace, however, show the inflectional spine appearing as an anti-current image which pushes the vertebra toward the concave side from the convex side (Figure 4.1). (a) (b) Figure 4.1 The x-ray films show an anti-current image. (a) before without a brace, (b) after with bracing Past studies have shown that the purpose of brace treatment is mainly to avoid further progression and not to correct the curve, giving the brace a holding effect (Veldhuizen, Cheung et al., 2002). Therefore, the brace treatment can be considered to be faulty when the curve further progresses more than 5 degrees after bracing (Bassett, Bunnell et al., 1986). 59

77 4.2 The effect of correction of IS by the 3D Airbag brace For early brace systems, the purpose of the treatment was mainly to prevent further progression of the spinal lateral curve rather than correcting the curve (Veldhuizen, 2002; Willner, 1984; Willers, 1993). A failed brace treatment is therefore defined as one in which the curve progresses more than 5 degrees after the bracing (Bassett, 1986; Montgomery, 1989; Veldhuizen, 2002). However, with advances in biomechanics and rehabilitation science, it is now possible to control spine curvature using a suitable brace design. An improperly prescribed, improperly designed, or improperly fitted brace will not work. Many reports of bad results from bracing may merely be the results of bad bracing (Emans, 2003). From the significant reduction in the Cobb angle during the follow up period, the airbag brace approach does appear to provide an effective correction treatment for IS subjects. Reduction of the Cobb angle was achieved in 27 out of 28 curves, with a reduction from 5 to 24 degrees, which is an average of 11.8 degrees. As a comparison, in a survey study of traditional Boston braces (Emans, 1986), out of 295 subjects, only 39% of subjects achieved a 5 degree reduction in the Cobb angle, and 4% achieved a 15 degree reduction. In the results of our study, from the clinical effects of the airbag brace, it can be certified that the subjects mean Cobb angle was decreased. Figure 4.2 shows that the x-ray film without the brace is different from that of the general brace. 60

78 Figure 4.2 Continuity treatments show the Cobb angle progressive decreases over an 18month period. Three factors are proposed to explain the success of this airbag treatment. The relatively easy adjustment of and control over airbag pressure is the most fundamental one. The traditional pad brace can only provide a supporting function to prevent progressive development of a spinal curve. In contrast, the correction force provided by the airbag is directly controlled by the pressure, which is easy to adjust and monitor. It is well-suited to the dynamic conditions of the correction process. The extra correction moment from a pair of airbags, which generated a force couples, might be the second factor for the success of the airbag brace. A derotation pad is 61

79 sometimes used in the traditional Boston brace to correct axial rotation, but its usage is rare. The majority of derotational corrective forces are built into the symmetrical Boston brace. The derotation pad is used only when the brace is mal-aligned due to severe axial rotation. In the airbag system, the correction moment can be applied whenever required because of the ease of application of the airbag and the direct control over the correction force. This generates a three-dimensional correction system. Last, but not least, the airbag is a deformable pneumatic module, which is more comfortable than the pad in the Boston brace. This will make subjects more willing to wear the 3D Airbag brace. It is inferred that the deformability of the airbag could continuously change the pressure distribution as well as the peak pressure site on the contact area as the subjects adjust their posture. The pad system has only a limited ability to vary the concentrated area for contact. A more comfortable interface condition can be achieved using the airbag system. This inference is indirectly supported by the over correction observation that occurred with the brace on. This over correction indicated a large correction force was applied directly to the trunk without inducing too much discomfort. In general, the traditional Boston brace with a pressure pad is only able to maintain the spinal curve, not correct it, even when the brace is on (Bulthuis, 2008; Lonstein, Winter et al., 1994; Goldberg, 1993). However, this inference requires further investigation. Finally it is noted that a minor change, less than 10%, of the contact force under various postures might also be a factor. This suggests that the airbag brace can provide continuous and sufficient correction force under different postural conditions. Moreover, based on the quantitative data provided in Table 3.3, the motion of lateral bending to the convex side and flexion are suggested to prevent in order not to reduce the correction force too much. 62

80 Despite its success in clinical outcomes, there are shortcomings in the usage of this airbag brace. The 3D Airbag brace is bulkier and heavier than the conventional brace, and some patients disliked the appearance of the brace. Also, this airbag approach provides the freedom to directly adjust the correction force, but determining the suitable pressure value still requires the expertise of an orthotist. Before providing the conclusions of this study, it is necessary to point out its major limitations: First of all, there was no control group that underwent brace treatment with pads instead of airbags. However, a lot of clinical data and research reports are available (Wiley, 2000; Marc, 2006; Weiss, 2007). For example, in a study by Wong (Wong 2000), 26 female AIS subjects were evaluated. The Cobb angle reduced from 34.4o±6.0 to 23.7o±7.7, which was almost the same as our study, which indicated an average of a 10o reduction. The major difference is that, evaluations of the Boston brace, other studies, including Wong, were measuring the Cobb angle with the brace on while in our study, the Cobb angle was measured without the brace on. It is then difficult to compare the angles directly due to different measurement conditions. However, the superiority of the airbag should be evident from the same amount of Cobb angle reduction. Using these studies as the comparison groups should be sufficient to demonstrate the treatment effect of the airbag approach. Secondly, there were only 20 subjects, and large variations existed among subjects. Nevertheless, significant reduction of the Cobb angle during the follow-up period provided strong evidence for the benefits of this airbag brace approach. 63

81 4.3 The effects of a wearing the Airbag brace on the back muscle activity of AIS patients AIS results in an imbalance in muscle tension on both sides of the spine, with further growth causing deterioration and the development of scoliosis (G erome, 2001). Both bracing treatment and surgery are clinical approaches that are able to prevent deterioration. In addition, while some studies report that the use of correct posture and appropriate exercise can prevent the deterioration associated with moderate scoliosis, few papers have examined how the use of a brace and posture influences the back muscle activity of scoliosis patients (Gignac, 2000). The results shown in Table 3.5 indicate that when wearing an airbag brace, the level of muscle activity decreases only during lateral bending on the coronal plane, while it increases significantly for the other exercises. Furthermore, although the levels of muscle activity under the out-of-brace exercise condition (Table 3.6.) are not significantly different, the EMG signal associated with trunk flexion is the smallest. In contrast, the levels of muscle activity under the in-brace exercise condition (Table 3.7.) are significantly different. In particular, the EMG value of trunk flexion, which is the smallest value in the out-of-brace condition, is the largest one in the in-brace condition. With regard to comparing movements, the sagittal plane and axial rotations of the horizontal plane are more significantly different than lateral bending of the coronal plane. With regard to the ratio of the muscle activity on both sides of the spine, in the out-of-brace condition, the muscle activity on the convex side is significantly larger than that on the concave side only for RTV. In the in-brace condition, the muscle activity on the convex side is larger than that on the concave side for both BSTV and BRTV. The spinal column is composed of vertebra and cartilage, and misarrangement of the 64

82 former cause spinal deformities. In addition, the muscles clinging to the spine are the main factors that control and influence the arrangement of the vertebra. The correction of scoliosis thus involves not only normal vertebra arrangement, but also balanced muscle tension on both sides of the spine. When treating unbalanced muscles, sufficient and continued stretch force is applied to the adaptably shortened soft tissue on the concave side of the spine to increase its length (Pamela, 2011). Overlong and weak muscles on the convex side of the spine are then able to restore normal muscle tension. The Cobb angle of the spine can increase if a scoliosis patient engages in improper exercise, while appropriate postures or movements can decrease this (see Fig. 4.3) (a) Erect posture (b) Left lateral bending (c) Right lateral bending Figure 4.3 Scoliosis movement to change the angle: (a). erect posture, the right convex on the thoracic and the left convex on the lumbar. (b). left lateral bending, the angle change on the thoracic increases and decreases on the lumbar. (c). right lateral bending, the angle change on the thoracic decreases and increases on the lumbar 65

83 However, the back muscle group is a set of complex and integrated muscles, and thus it is not easy to train the motor control of individual muscles. Nevertheless, Fig.4.4 shows that the use of a brace can not only change the Cobb angle and the shape of the spine, but also can improve the length-tension relationship of the back muscle group (Christa, 2007). (a) before wear brace (b) after wear brace Figure4.4 X-ray showing the curve of spine may be changed by the airbag brace. (a) Without the airbag brace, the curve occurred in the thoracolumbar region. (b) With the Airbag brace, the spine can be made erect by the brace in the thoracolumbar region. As a result, the muscle group used during in-brace exercise is significantly different from that used during the out-of-brace exercise when carrying out the same movement, as explained in more detail as follows: First, the use of a brace increases the amount of muscle activity in the movement of both the sagittal plane and the horizontal plane. The brace may cause the spine to become more erect, so the muscle groups on both sides 66