589466 research-article2015
POI0010.1177/0309364615589466Prosthetics and Orthotics InternationalArazpour et al.
INTERNATIONAL SOCIETY FOR PROSTHETICS AND ORTHOTICS
Original Research Report
The influence of thermoplastic thoraco lumbo sacral orthoses on standing balance in subjects with idiopathic scoliosis
Prosthetics and Orthotics International 1–7 © The International Society for Prosthetics and Orthotics 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0309364615589466 poi.sagepub.com
Minoo Khanal1, Mokhtar Arazpour2,3, Mahmood Bahramizadeh2, Mohammad Samadian4, Stephen W Hutchins5, Reza Vahab Kashani2, Mohammad A Mardani2, Hossein Vahid Tari6, Atefeh Aboutorabi2, Sarah Curran7 and Heidar Sadeghi8 Abstract Background: Idiopathic scoliosis patients have postural equilibrium problems. Objective: The objective of this study was to assess postural control in subjects with idiopathic scoliosis following a 4-month intervention in an unbraced position. Study design: Quasi-experimental. Methods: Eight healthy girls and eight girls with idiopathic scoliosis took part. A Kistler force platform was used with a frequency of 100 Hz for recording data. The center of pressure was recorded in different positions out of brace for scoliosis and healthy subjects. Test conditions were single limb and double limb stance, with eyes open and closed, and foam and rigid surfaces. Results: The data reflected a weak balance of idiopathic scoliosis subjects compared to healthy subjects. After 1 and 4 months of wearing the brace, center of pressure and center of gravity sway increased in the majority of the tests, although there were no significant differences in any of the test conditions (p > 0.05). While the center of pressure sway in medio-lateral direction decreased after 4 months of wearing a brace, in other variables center of pressure and center of gravity sway increased. Conclusion: Idiopathic scoliosis patients have weak balance in comparison to healthy subjects. In addition, following a period of 4 months of wearing a brace, balance parameters in the scoliosis subjects did not improve. The results show that we need more follow-up of orthoses wearing in idiopathic scoliosis subjects and suggest more studies at least 1-year follow-up to identify the efficiency of brace wear on balance. Clinical relevance Scoliosis can alter postural stability and balance performance during quiet standing. Spinal deformity can alter a subject’s ability to compensate for postural changes and cause gait deviations. This study investigated balance differences between the healthy and idiopathic scoliosis patients and the results of thoraco lumbo sacral orthosis brace wear. It might provide some new insight into the conservative treatment of idiopathic scoliosis patients for clinicians and researchers. Keywords Spinal orthoses, idiopathic scoliosis, balance Date received: 23 May 2014; accepted: 3 April 2015
Background Normal curvature of the spine keeps the head over the pelvis and acts like as a shock absorber in order to distribute the
Center of Red Crescent Society of Iran, Tehran, Iran of Orthotics and Prosthetics, University of Social Welfare and Rehabilitation Sciences, Tehran, Islamic Republic of Iran 3Pediatric Neurorehabilitation Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran 4Loghman Hakim hospital, Shahid Beheshti University of Medical Sciences, Department of Neurosurgery, Tehran, Iran 5IHSCR, Faculty of Health & Social Care, University of Salford, Salford, UK 6Iran University of Medical Sciences, Tehran, Iran
mechanical forces during movements.1 In individuals with scoliosis, these normal curves become abnormal. Small alterations in the body’s upright alignment require
1Rehabilitation 2Department
7Cardiff 8Tarbiat
Metropolitan University, Cardiff, UK Moallem University, Tehran, Islamic Republic of Iran
Corresponding author: Mokhtar Arazpour, Department of Orthotics and Prosthetics, University of Social Welfare and Rehabilitation Sciences, Kodakyarst, Daneshjo Blvd, Evin, Tehran 1985713834, Iran. Email: [email protected]
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Prosthetics and Orthotics International
Table 1. The demographic data of the participants with idiopathic scoliosis. No.
Age (year)
Weight (kg)
Height (m)
Curve pattern
Cobb angle (degree)
Apex level
1 2 3 4 5 6 7 8
13 13.5 14.5 13.5 12 13 12 12.5
51 55 56 56 47 48 47 46
1.58 1.59 1.59 1.60 1.45 1.48 1.47 1.45
Left lumbar Left lumbar Right thoracolumbar Right thoracolumbar Left lumbar Right thoracolumbar Left lumbar Left lumbar
25 30 35 26 27 32 34 29
L2 L2 T12–L1 T12–L1 L2 T12–L1 L2 L2
corrective torques to maintain the balance and stability. Human upright posture is adjusted through continuous reactions to sensory information from the proprioceptive, visual, and vestibular systems.2 A scoliotic deformity can alter postural stability and balance performance during quiet standing.3–7 Idiopathic scoliosis (IS) patients are considered to have postural equilibrium problems.7,8 Studies have shown that IS patients have poor postural control compared with individuals of the same age group without scoliosis.9–12 These studies indicate that there is a change in processing of motor-sensory information or in sensory integration in these individuals, causing more sway in their center of pressure (CoP) especially in subjects with spinal curvatures greater than 40°.9–12 An increase in the sway areas and higher CoP variations have been noted for scoliosis patients which were attributed to a greater neuromuscular demand to maintain standing balance.6,13,14 In addition, biomechanical alterations such as deformity of the spinal cord,15 muscle imbalance between both sides of the spine16 and poor relationships among body segments17 can occur. Deviations of both the center of mass (CoM) and gravity line from their ideal positions also seem to influence the increase of postural sway.18 Byl and Gray19 found that the balance behavior between normal subjects and IS patients were similar in static balance positions. De Gauzy et al.20 and Chow et al.21 demonstrated that a poorer balance performance was exhibited by participants with adolescent idiopathic scoliosis (AIS) when wearing a thoraco lumbo sacral orthosis (TLSO) brace which indicated that bracing might not have an instant effect on a balance control system. However, Lamantia et al.22 found an immediate increase in cerebellar feedback due to bracing in scoliotic patients and improved central brainstem function in the cases studied. Bernard and Valero’s23 and Sadeghi et al.’s24 studies reported that there were no differences in the sway area or in the length of the CoP excursion of AIS subjects for braced and unbraced conditions. Studies have therefore shown controversy in the effect of spinal orthoses on standing balance with wearing orthoses; however, to the authors’ knowledge, there has been no study that assessed the effect of spinal orthoses wear on standing balance in IS while not wearing the
brace. Therefore, the objective of this study was to assess postural control in situations of visual deprivation and different plantar surfaces to determine which of these conditions are more influential on the maintenance of postural control in subjects with IS. This was tested at baseline, and after 1 and 4 months after being supplied with a spinal brace but without the brace being worn during testing.
Method Subjects Eight girls with IS aged between 10 and 18 years (mean ± standard deviation (SD): 13.00 ± 0.816 years) with thoracolumbar or lumbar curve patterns were selected to participate in this quasi-experimental and clinical trial study (Table 1). Eight healthy subjects (girls, aged: 13.00 ± 1.33 years, body mass index (BMI): 21.76 ± 0.576 kg/m2), without any symptoms, neuromuscular, and orthopedic disorders, and without history of ankle, knee, or hip pain, were also recruited as a control group. All the healthy subjects were matched according to age and BMI with subjects with AIS. To detect the difference between adolescents with IS and healthy subjects in postural instability, healthy subjects were used as control group in this study. The inclusion criteria to select subjects were the presence of curves with a Cobb angle of between 25° and 35°, scoliosis apex up to T8, and the absence of other spinal deformities. Subjects were excluded if they had any balance disorder caused by certain diseases, hearing or visual impairment, history of drugs use that affected balance in last 12 h, recent surgery or fracture in limbs or spine, and bone or muscle pain that based on a visual analog scale was less than 3. A sample size calculation was performed prior to the study. The numbers of subjects were determined to have a power of 0.80 and α = 0.05 based on the following formula24
N=
σ d2 ( z1−α / 2 + z1− β )
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Figure 1. The thoraco lumbo sacral orthosis (TLSO) used in this study. Table 2. Test procedure.
Double-limb stance Single-limb stance
Standing on foam surface
Standing on rigid surface
Eyes opened Eyes closed Eyes opened Eyes closed
Eyes opened Eyes closed Eyes opened Eyes closed
Orthotic devices To ensure technical consistency, eight thermoplastic TLSOs were fabricated for scoliosis subjects by one person according to the orthopedic specialist prescription (Figure 1). This bespoke TLSO was fabricated based on the Miami Boston spinal orthosis design. All of the braces were manufactured from a polypropylene sheet. The anterior inferior trim lines were kept as low as the patient could tolerate. Anterior superior trim lines extended from the xiphoid process to the symphysis pubis. Posterior superior trim line originated at the spine of the scapula and posterior inferior trim line extended as low as possible, but not more than one finger width from the seat when the patient was sitting with hips flexed at 90°. Lateral trim lines originated from below the level of the axilla to allow the patient to complete a full range of motion of the arms.25 The pads were triangular shaped and the padding area was determined for IS subjects according to an X-ray image at the rib of the apex vertebra in posterior-lateral area and in order that appropriate corrective force could be applied with an opposite side cut out.
Apparatus and test procedure A Kistler force platform (model 9286A) was used with a frequency of 100 Hz for recording data. BioWare software
was also used for analyzing the recorded CoP data. The IS patients were instructed to wear the brace 23 h per day. Balance tests were accomplished at study onset, and 1 and 4 months after TLSO wear in the IS subjects, while healthy subjects were tested only at the study onset. The test procedure is summarized in Table 2. Each group had the following test conditions: single-limb and double-limb stance, with eyes open and closed, while standing on foam (diameter of 10 cm) or a rigid surface. Each test was repeated three times. To avoid boredom, the participants were allowed a 5-min rest period between each test. The test order was randomized for each girl to minimize any learning effect. Duration of each test was taken to be 20 s.26 The CoP data were recorded in different positions out of brace for scoliosis and healthy subjects. All of the subjects and the examiner were blinded to the test procedure. In double-stance tests, each subject stood barefoot with arms relaxed at the sides, in a comfortable stance with the distance between heels from medial malleus being 10 cm27 with the toe-out angles between the two feet being 30°.28 For single upright balance evaluation, the subjects were required to stand on the dominant limb with their arms relaxed at the sides. When a person’s eyes were opened, subjects were staring to a specific point within approximately 3 m. The CoP motion parameters were recorded as medio-lateral (ML)
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Table 3. Comparison of center of pressure (CoP) sway between scoliosis and healthy subjects on the first day. Variable
ML sway AP sway LoP
Surface
Hard surface Foam surface Hard surface Foam surface Hard surface Foam surface
Position
Double standing
Eyes opened Eyes closed Eyes opened Eyes closed Eyes opened Eyes closed Eyes opened Eyes closed Eyes opened Eyes closed Eyes opened Eyes closed
Standing on dominant limb
Mean ± SD (scoliosis)
Mean ± SD (healthy)
p value
Mean ± SD (scoliosis)
Mean ± SD (healthy)
p value
0.113 ± 0.008 0.108 ± 0 0.080 ± 0 0.084 ± 0 0.056 ± 0.042 0.084 ± 0.081 0.048 ± 0.018 0.084 ± 0.132 0.371 ± 0.228 0.358 ± 0.212 0.324 ± 0.227 0.398 ± 0.358
0.065 ± 0.062 0.073 ± 0.039 0.083 ± 0.015 0.046 ± 0.067 0.043 ± 0.005 0.038 ± 0.023 0.077 ± 0.019 0.070 ± 0.019 0.114 ± 0.061 0.196 ± 0.297 0.093 ± 0.067 0.126 ± 0.045
0.798 0.037 0.488 0.068 0.410 0.072 0.000 0.013 0.510 0.012 0.086 0.077
0.021 ± 0.006 0.027 ± 0.029 0.014 ± 0.013 0.003 ± 0.006 0.051 ± 0.044 0.041 ± 0.040 0.040 ± 0.035 0.026 ± 0.025 0.184 ± 0.130 0.168 ± 0.145 0.210 ± 0.185 0.219 ± 0.227
0.045 ± 0.051 0.062 ± 0.064 0.024 ± 0.026 0.035 ± 0.035 0.057 ± 0.010 0.033 ± 0.042 0.076 ± 0.012 0.082 ± 0.013 0.114 ± 0.061 0.196 ± 0.297 0.093 ± 0.067 0.126 ± 0.045
0.273 0.176 0.437 0.619 0.719 0.161 0.008 0.000 0.227 0.627 0.125 0.060
SD: standard deviation; ML: medio-lateral; AP: anterior-posterior; LoP: length of path.
CoP displacement (CoPX) and anterior-posterior (AP) CoP displacement (CoPY) and length of path (LoP) of center of gravity (CoG). Prior to the test, all the subjects and their parents were asked to give an informed consent prior to taking part in the experiment. Ethical approval was obtained from the ethics committee of University of Social Welfare and Rehabilitation Science.
Statistical analysis The mean and SD of variables were calculated for each subject. The normal distribution of all variables was tested by Kolmogorov–Smirnov test. Since the parameters had a normal distribution, the parametric statistical test was adopted. Independent-samples T-tests were used to compare the mean CoP values between the normal and IS subjects. Repeated measures analysis of variance (ANOVA) was employed to analyze the mean value of each variable, with within-subjects factors of vision (eye open and closed), surface (rigid and foam), and stance condition (single or double limb support). Data analysis was performed using the SPSS 19, and level of significance was considered less than 0.05.
Results Comparison between healthy subjects and patients with IS at study onset (first day) ML CoP sway. In double standing, in one position (standing with closed eyes on a hard surface), p = 0.037, meaningful difference was seen between healthy subjects and patients with IS at study onset (first day). However, in standing on
dominant limb, there was no significant difference between the two groups in this parameter (Table 3). AP CoP sway. The average displacement of the CoP when scoliosis subjects stood on two feet compared to healthy subjects decreased except standing on the hard surface with closed eyes. There was significant difference in standing on two feet on a soft surface with opened eyes (p ⩽ 0.001) and with closed eyes (p = 0.013) between healthy and scoliosis subjects. In unilateral standing on dominant limb, there were significant differences between healthy and scoliosis subjects in standing on a soft surface with opened (p = 0.008) and closed eyes (p ⩽ 0.001) (Table 3). LoP of CoG in x-axis. In double standing, there was significant difference only on the hard surface with closed eyes in scoliosis subjects compared to healthy subjects in the LoP of the CoG (p = 0.012). However, in standing on dominant limb, there was no significant difference between the two groups in this parameter (p > 0.05) (Table 3).
Comparisons of CoP sway in subjects with IS in double standing CoP sway in ML axis. CoP sway in ML axis decreased in 4 months after wearing brace, while CoP sway increased in comparison between first day and 1 month after wearing brace. There was significant difference between 1 and 4 months after wearing brace (p 0.05).
Discussion Under normal conditions, balance is maintained predominantly by an ankle strategy to maintain CoP on the base of support. However, when there is a strong perturbation, a hip strategy is employed to maintain balance. Therefore, in situations like standing on unstable surfaces such as foam, or standing on one leg due to loss of support and ankle defects in sensory information for balance, strategy controls may not be sufficient, which causes the CoP sway to increase leading to instability.10 On the first day of the test, data reflected the weak balance of IS subjects compared to healthy subjects. The amount of CoP and CoG sway increased to keep balance especially when subjects stood on a foam surface with closed eyes. These observations share similarities to previous studies. Chen et al.17 in 1998 and Nault et al.6 in 2002 in a comparative study between healthy and scoliosis subjects showed patients with scoliosis have less balance than normal subjects, and if visual and proprioception systems are involved, scoliosis subjects adopt more trunk motion to maintain balance. Adler et al.15 found that scoliosis patients who wore a brace had better balance than patients who did not use a brace (tests were performed without the brace). The results suggest that wearing a brace might have a therapeutic effect on balance for patients with IS and despite reporting a negative impact on the balance with a brace, it may cause a long-term learning effect and a gradual improvement in balance performance.15 However, Sadeghi et al.24 in 2008 included 15 female patients with IS who had used a Boston brace. The 4-month follow-up study similar to our study follow-up showed that mean position of the CoP and the displacement were similar with and without braces. Nevertheless, in this study, after 1 and 4 months of wearing brace CoP and CoG sway
increased almost in all of the tests although there were no significant differences in all of the test conditions. However, the CoP sway in ML decreased after 4 months of wearing brace but in other variables CoP and CoG sway increased. The decrease in CoP sway in ML could be a result from the frontal curve correction, and the increase in CoG sway can result from enhancement of body sway for balance control. De Gauzy et al.20 in 2002 showed a similar result, and disruption of balance with thoraco lumbo sacral was seen. Therefore, in general, the brace did not deduct from the amount of CoP sway. Comparison between the results of 1 and 4 months of wearing brace showed that nearly in all of the test conditions, CoP sway area increased. These results could not indicate the learning effect of wearing brace after 4 months. Therefore, the authors concluded that the brace disrupted the balance in scoliosis patients. The limitations of this study were the period of extended evaluation which caused some of the subjects to withdraw, which in turn resulted in only girls participating. In this study, the CoP swing in ML, AP, and mean displacement of the CoG in the direction of the x-axis (LoP) in healthy and IS subjects were evaluated on the first day, 1 month, and 4 months after wearing brace. Future studies should therefore include the following: •• Study on the effect of brace on gait kinematics in individuals with scoliosis. •• The study of kinematic and kinetic parameters of wearing brace. •• Similar studies in both sexes in order to compare problems and therapeutic responses of girls and boys. •• Addition of various static and dynamic balance tests in order to generalize the results.
Conclusion In this study, it was found that IS subjects have poor (weak) balance in comparison to healthy subjects. Indeed, changes in processing of motor-sensory information or in sensory integration in IS subjects, causing more sway in their CoP, were attributed to a greater neuromuscular demand to maintain standing balance. In addition, wearing a brace for a period of 4 months did not produce an improvement in balance parameters in scoliosis subjects, and if vision is removed, caused further disturbance on the balance. The findings of this study indicate that there is a requirement to follow up the use and wear of orthoses in IS individuals. In particular, further studies need to focus on providing at least 1-year follow-up to identify the efficiency of brace on balance. Author contribution All authors contributed equally in the preparation of this article.
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Khanal et al. Declaration of conflicting interests The authors did not have any conflicts of interest with regard to the study presented in this article.
Funding This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
References 1. Bernhardt M, Bridwell KH and DeWald RL. Normal spinal anatomy: normal sagittal plane alignment. In: Bridwell KH and DeWald RL (eds) The textbook of spinal surgery, vol. 1. Philadelphia, PA: Lippincott-Raven, 1997, pp. 185–191. 2. Peterka RJ and Loughlin PJ. Dynamic regulation of sensorimotor integration in human postural control. J Neurophysiol 2004; 91(1): 410–423. 3. Moe JH and Lonstein JE. Moe’s textbook of scoliosis and other spinal deformities. Philadelphia, PA: W.B. Saunders, 1995. 4. Beaulieu M, Toulotte C, Gatto L, et al. Postural imbalance in non-treated adolescent idiopathic scoliosis at different periods of progression. Eur Spine J 2009; 18(1): 38–44. 5. Sahlstrand T, Örtengren R and Nachemson A. Postural equilibrium in adolescent idiopathic scoliosis. Acta Orthop Scand 1978; 49(4): 354–365. 6. Nault M-L, Allard P, Hinse S, et al. Relations between standing stability and body posture parameters in adolescent idiopathic scoliosis. Spine 2002; 27(17): 1911–1917. 7. Zabjek KF, Leroux MA, Coillard C, et al. Evaluation of segmental postural characteristics during quiet standing in control and idiopathic scoliosis patients. Clin Biomech 2005; 20(5): 483–490. 8. Hufschmidt A, Dichgans J, Mauritz K-H, et al. Some methods and parameters of body sway quantification and their neurological applications. Arch Psychiatr Nervenkr 1980; 228(2): 135–150. 9. Cheng JC, Guo X, Sher AH, et al. Correlation between curve severity, somatosensory evoked potentials, and magnetic resonance imaging in adolescent idiopathic scoliosis. Spine 1999; 24(16): 1679–1684. 10. Simoneau M, Mercier P, Blouin J, et al. Altered sensoryweighting mechanisms is observed in adolescents with idiopathic scoliosis. BMC Neurosci 2006; 7(1): 68. 11. Guo X, Chau WW, Hui-Chan CW, et al. Balance control in adolescents with idiopathic scoliosis and disturbed somatosensory function. Spine 2006; 31(14): E437–E440. 12. Chen T-H, Tsuang Y-H, Huang S-C, et al. Body center of pressure in idiopathic scoliosis. J Orthop Surg Taiwan 1994; 11(4): 215–221. 13. Lidström J, Friberg S, Lindström L, et al. Postural control in siblings to scoliosis patients and scoliosis patients. Spine 1988; 13(9): 1070–1074.
14. Driscoll DM, Newton RA, Lamb RL, et al. A study of postural equilibrium in idiopathic scoliosis. J Pediatr Orthop 1984; 4(6): 677–681. 15. Adler N, Bleck E, Rinsky L, et al. Balance reactions and eye-hand coordination in idiopathic scoliosis. J Orthop Res 1986; 4(1): 102–107. 16. Ford D, Bagnall K, Clements C, et al. Muscle spindles in the paraspinal musculature of patients with adolescent idiopathic scoliosis. Spine 1988; 13(5): 461–465. 17. Chen P-Q, Wang J-L, Tsuang Y-H, et al. The postural stability control and gait pattern of idiopathic scoliosis adolescents. Clin Biomech 1998; 13(1): S52–S58. 18. Gauchard GC, Lascombes P, Kuhnast M, et al. Influence of different types of progressive idiopathic scoliosis on static and dynamic postural control. Spine 2001; 26(9): 1052– 1058. 19. Byl NN and Gray JM. Complex balance reactions in different sensory conditions: adolescents with and without idiopathic scoliosis. J Orthop Res 1993; 11(2): 215–227. 20. De Gauzy JS, Domenech P, Dupui P, et al. Effect of bracing on postural balance in idiopathic scoliosis. Stud Health Technol Inform 2002; 88: 239–240. 21. Chow DH, Kwok ML, Cheng JC, et al. The effect of backpack weight on the standing posture and balance of schoolgirls with adolescent idiopathic scoliosis and normal controls. Gait Posture 2006; 24(2): 173–181. 22. Lamantia MJ, Deutchman G and Bagley C. Oculomotor functional improvement in scoliotic children (International conference on conservative management of spinal deformities, Barcelona, 23–24 January 2004). Pediatr Rehabil 2004; 7(1): 51–64. 23. Bernard J-C and Valero J-P. Mesures stabilométriques des paramètres de l’équilibre statique de 26 patients scoliotiques avant et après traitement. Annales de kinésithérapie 1999; 26: 145–153. 24. Sadeghi H, Allard P, Barbier F, et al. Bracing has no effect on standing balance in females with adolescent idiopathic scoliosis. Med Sci Monit 2008; 14(6): CR293–CR298. 25. Grivas T. The Boston brace system philosophy, biomechanics, design & fit. In: Grivas TB (ed.) The conservative scoliosis treatment: 1st SOSORT instructional course lectures book, vol. 1. Amsterdam: IOS Press, 2008, p. 370. 26. Eshraghi A, Maroufi N, Sanjari MA, et al. Effect of Milwaukee brace on static and dynamic balance of female hyperkyphotic adolescents. Prosthet Orthot Int 2013; 37(1): 76–84. 27. DeWaard BP, Bentrup BR, Hollman JH, et al. Relationship of the functional reach and lateral reach tests in elderly females. J Geriatr Phys Ther 2002; 25(3): 4–9. 28. Luoto S, Aalto H, Taimela S, et al. One-footed and externally disturbed two-footed postural control in patients with chronic low back pain and healthy control subjects: a controlled study with follow-up. Spine 1998; 23(19): 2081–2089.
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POI0010.1177/0309364615589466Prosthetics and Orthotics InternationalArazpour et al.
INTERNATIONAL SOCIETY FOR PROSTHETICS AND ORTHOTICS
Original Research Report
The influence of thermoplastic thoraco lumbo sacral orthoses on standing balance in subjects with idiopathic scoliosis
Prosthetics and Orthotics International 1–7 © The International Society for Prosthetics and Orthotics 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0309364615589466 poi.sagepub.com
Minoo Khanal1, Mokhtar Arazpour2,3, Mahmood Bahramizadeh2, Mohammad Samadian4, Stephen W Hutchins5, Reza Vahab Kashani2, Mohammad A Mardani2, Hossein Vahid Tari6, Atefeh Aboutorabi2, Sarah Curran7 and Heidar Sadeghi8 Abstract Background: Idiopathic scoliosis patients have postural equilibrium problems. Objective: The objective of this study was to assess postural control in subjects with idiopathic scoliosis following a 4-month intervention in an unbraced position. Study design: Quasi-experimental. Methods: Eight healthy girls and eight girls with idiopathic scoliosis took part. A Kistler force platform was used with a frequency of 100 Hz for recording data. The center of pressure was recorded in different positions out of brace for scoliosis and healthy subjects. Test conditions were single limb and double limb stance, with eyes open and closed, and foam and rigid surfaces. Results: The data reflected a weak balance of idiopathic scoliosis subjects compared to healthy subjects. After 1 and 4 months of wearing the brace, center of pressure and center of gravity sway increased in the majority of the tests, although there were no significant differences in any of the test conditions (p > 0.05). While the center of pressure sway in medio-lateral direction decreased after 4 months of wearing a brace, in other variables center of pressure and center of gravity sway increased. Conclusion: Idiopathic scoliosis patients have weak balance in comparison to healthy subjects. In addition, following a period of 4 months of wearing a brace, balance parameters in the scoliosis subjects did not improve. The results show that we need more follow-up of orthoses wearing in idiopathic scoliosis subjects and suggest more studies at least 1-year follow-up to identify the efficiency of brace wear on balance. Clinical relevance Scoliosis can alter postural stability and balance performance during quiet standing. Spinal deformity can alter a subject’s ability to compensate for postural changes and cause gait deviations. This study investigated balance differences between the healthy and idiopathic scoliosis patients and the results of thoraco lumbo sacral orthosis brace wear. It might provide some new insight into the conservative treatment of idiopathic scoliosis patients for clinicians and researchers. Keywords Spinal orthoses, idiopathic scoliosis, balance Date received: 23 May 2014; accepted: 3 April 2015
Background Normal curvature of the spine keeps the head over the pelvis and acts like as a shock absorber in order to distribute the
Center of Red Crescent Society of Iran, Tehran, Iran of Orthotics and Prosthetics, University of Social Welfare and Rehabilitation Sciences, Tehran, Islamic Republic of Iran 3Pediatric Neurorehabilitation Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran 4Loghman Hakim hospital, Shahid Beheshti University of Medical Sciences, Department of Neurosurgery, Tehran, Iran 5IHSCR, Faculty of Health & Social Care, University of Salford, Salford, UK 6Iran University of Medical Sciences, Tehran, Iran
mechanical forces during movements.1 In individuals with scoliosis, these normal curves become abnormal. Small alterations in the body’s upright alignment require
1Rehabilitation 2Department
7Cardiff 8Tarbiat
Metropolitan University, Cardiff, UK Moallem University, Tehran, Islamic Republic of Iran
Corresponding author: Mokhtar Arazpour, Department of Orthotics and Prosthetics, University of Social Welfare and Rehabilitation Sciences, Kodakyarst, Daneshjo Blvd, Evin, Tehran 1985713834, Iran. Email: [email protected]
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Table 1. The demographic data of the participants with idiopathic scoliosis. No.
Age (year)
Weight (kg)
Height (m)
Curve pattern
Cobb angle (degree)
Apex level
1 2 3 4 5 6 7 8
13 13.5 14.5 13.5 12 13 12 12.5
51 55 56 56 47 48 47 46
1.58 1.59 1.59 1.60 1.45 1.48 1.47 1.45
Left lumbar Left lumbar Right thoracolumbar Right thoracolumbar Left lumbar Right thoracolumbar Left lumbar Left lumbar
25 30 35 26 27 32 34 29
L2 L2 T12–L1 T12–L1 L2 T12–L1 L2 L2
corrective torques to maintain the balance and stability. Human upright posture is adjusted through continuous reactions to sensory information from the proprioceptive, visual, and vestibular systems.2 A scoliotic deformity can alter postural stability and balance performance during quiet standing.3–7 Idiopathic scoliosis (IS) patients are considered to have postural equilibrium problems.7,8 Studies have shown that IS patients have poor postural control compared with individuals of the same age group without scoliosis.9–12 These studies indicate that there is a change in processing of motor-sensory information or in sensory integration in these individuals, causing more sway in their center of pressure (CoP) especially in subjects with spinal curvatures greater than 40°.9–12 An increase in the sway areas and higher CoP variations have been noted for scoliosis patients which were attributed to a greater neuromuscular demand to maintain standing balance.6,13,14 In addition, biomechanical alterations such as deformity of the spinal cord,15 muscle imbalance between both sides of the spine16 and poor relationships among body segments17 can occur. Deviations of both the center of mass (CoM) and gravity line from their ideal positions also seem to influence the increase of postural sway.18 Byl and Gray19 found that the balance behavior between normal subjects and IS patients were similar in static balance positions. De Gauzy et al.20 and Chow et al.21 demonstrated that a poorer balance performance was exhibited by participants with adolescent idiopathic scoliosis (AIS) when wearing a thoraco lumbo sacral orthosis (TLSO) brace which indicated that bracing might not have an instant effect on a balance control system. However, Lamantia et al.22 found an immediate increase in cerebellar feedback due to bracing in scoliotic patients and improved central brainstem function in the cases studied. Bernard and Valero’s23 and Sadeghi et al.’s24 studies reported that there were no differences in the sway area or in the length of the CoP excursion of AIS subjects for braced and unbraced conditions. Studies have therefore shown controversy in the effect of spinal orthoses on standing balance with wearing orthoses; however, to the authors’ knowledge, there has been no study that assessed the effect of spinal orthoses wear on standing balance in IS while not wearing the
brace. Therefore, the objective of this study was to assess postural control in situations of visual deprivation and different plantar surfaces to determine which of these conditions are more influential on the maintenance of postural control in subjects with IS. This was tested at baseline, and after 1 and 4 months after being supplied with a spinal brace but without the brace being worn during testing.
Method Subjects Eight girls with IS aged between 10 and 18 years (mean ± standard deviation (SD): 13.00 ± 0.816 years) with thoracolumbar or lumbar curve patterns were selected to participate in this quasi-experimental and clinical trial study (Table 1). Eight healthy subjects (girls, aged: 13.00 ± 1.33 years, body mass index (BMI): 21.76 ± 0.576 kg/m2), without any symptoms, neuromuscular, and orthopedic disorders, and without history of ankle, knee, or hip pain, were also recruited as a control group. All the healthy subjects were matched according to age and BMI with subjects with AIS. To detect the difference between adolescents with IS and healthy subjects in postural instability, healthy subjects were used as control group in this study. The inclusion criteria to select subjects were the presence of curves with a Cobb angle of between 25° and 35°, scoliosis apex up to T8, and the absence of other spinal deformities. Subjects were excluded if they had any balance disorder caused by certain diseases, hearing or visual impairment, history of drugs use that affected balance in last 12 h, recent surgery or fracture in limbs or spine, and bone or muscle pain that based on a visual analog scale was less than 3. A sample size calculation was performed prior to the study. The numbers of subjects were determined to have a power of 0.80 and α = 0.05 based on the following formula24
N=
σ d2 ( z1−α / 2 + z1− β )
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Figure 1. The thoraco lumbo sacral orthosis (TLSO) used in this study. Table 2. Test procedure.
Double-limb stance Single-limb stance
Standing on foam surface
Standing on rigid surface
Eyes opened Eyes closed Eyes opened Eyes closed
Eyes opened Eyes closed Eyes opened Eyes closed
Orthotic devices To ensure technical consistency, eight thermoplastic TLSOs were fabricated for scoliosis subjects by one person according to the orthopedic specialist prescription (Figure 1). This bespoke TLSO was fabricated based on the Miami Boston spinal orthosis design. All of the braces were manufactured from a polypropylene sheet. The anterior inferior trim lines were kept as low as the patient could tolerate. Anterior superior trim lines extended from the xiphoid process to the symphysis pubis. Posterior superior trim line originated at the spine of the scapula and posterior inferior trim line extended as low as possible, but not more than one finger width from the seat when the patient was sitting with hips flexed at 90°. Lateral trim lines originated from below the level of the axilla to allow the patient to complete a full range of motion of the arms.25 The pads were triangular shaped and the padding area was determined for IS subjects according to an X-ray image at the rib of the apex vertebra in posterior-lateral area and in order that appropriate corrective force could be applied with an opposite side cut out.
Apparatus and test procedure A Kistler force platform (model 9286A) was used with a frequency of 100 Hz for recording data. BioWare software
was also used for analyzing the recorded CoP data. The IS patients were instructed to wear the brace 23 h per day. Balance tests were accomplished at study onset, and 1 and 4 months after TLSO wear in the IS subjects, while healthy subjects were tested only at the study onset. The test procedure is summarized in Table 2. Each group had the following test conditions: single-limb and double-limb stance, with eyes open and closed, while standing on foam (diameter of 10 cm) or a rigid surface. Each test was repeated three times. To avoid boredom, the participants were allowed a 5-min rest period between each test. The test order was randomized for each girl to minimize any learning effect. Duration of each test was taken to be 20 s.26 The CoP data were recorded in different positions out of brace for scoliosis and healthy subjects. All of the subjects and the examiner were blinded to the test procedure. In double-stance tests, each subject stood barefoot with arms relaxed at the sides, in a comfortable stance with the distance between heels from medial malleus being 10 cm27 with the toe-out angles between the two feet being 30°.28 For single upright balance evaluation, the subjects were required to stand on the dominant limb with their arms relaxed at the sides. When a person’s eyes were opened, subjects were staring to a specific point within approximately 3 m. The CoP motion parameters were recorded as medio-lateral (ML)
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Prosthetics and Orthotics International
Table 3. Comparison of center of pressure (CoP) sway between scoliosis and healthy subjects on the first day. Variable
ML sway AP sway LoP
Surface
Hard surface Foam surface Hard surface Foam surface Hard surface Foam surface
Position
Double standing
Eyes opened Eyes closed Eyes opened Eyes closed Eyes opened Eyes closed Eyes opened Eyes closed Eyes opened Eyes closed Eyes opened Eyes closed
Standing on dominant limb
Mean ± SD (scoliosis)
Mean ± SD (healthy)
p value
Mean ± SD (scoliosis)
Mean ± SD (healthy)
p value
0.113 ± 0.008 0.108 ± 0 0.080 ± 0 0.084 ± 0 0.056 ± 0.042 0.084 ± 0.081 0.048 ± 0.018 0.084 ± 0.132 0.371 ± 0.228 0.358 ± 0.212 0.324 ± 0.227 0.398 ± 0.358
0.065 ± 0.062 0.073 ± 0.039 0.083 ± 0.015 0.046 ± 0.067 0.043 ± 0.005 0.038 ± 0.023 0.077 ± 0.019 0.070 ± 0.019 0.114 ± 0.061 0.196 ± 0.297 0.093 ± 0.067 0.126 ± 0.045
0.798 0.037 0.488 0.068 0.410 0.072 0.000 0.013 0.510 0.012 0.086 0.077
0.021 ± 0.006 0.027 ± 0.029 0.014 ± 0.013 0.003 ± 0.006 0.051 ± 0.044 0.041 ± 0.040 0.040 ± 0.035 0.026 ± 0.025 0.184 ± 0.130 0.168 ± 0.145 0.210 ± 0.185 0.219 ± 0.227
0.045 ± 0.051 0.062 ± 0.064 0.024 ± 0.026 0.035 ± 0.035 0.057 ± 0.010 0.033 ± 0.042 0.076 ± 0.012 0.082 ± 0.013 0.114 ± 0.061 0.196 ± 0.297 0.093 ± 0.067 0.126 ± 0.045
0.273 0.176 0.437 0.619 0.719 0.161 0.008 0.000 0.227 0.627 0.125 0.060
SD: standard deviation; ML: medio-lateral; AP: anterior-posterior; LoP: length of path.
CoP displacement (CoPX) and anterior-posterior (AP) CoP displacement (CoPY) and length of path (LoP) of center of gravity (CoG). Prior to the test, all the subjects and their parents were asked to give an informed consent prior to taking part in the experiment. Ethical approval was obtained from the ethics committee of University of Social Welfare and Rehabilitation Science.
Statistical analysis The mean and SD of variables were calculated for each subject. The normal distribution of all variables was tested by Kolmogorov–Smirnov test. Since the parameters had a normal distribution, the parametric statistical test was adopted. Independent-samples T-tests were used to compare the mean CoP values between the normal and IS subjects. Repeated measures analysis of variance (ANOVA) was employed to analyze the mean value of each variable, with within-subjects factors of vision (eye open and closed), surface (rigid and foam), and stance condition (single or double limb support). Data analysis was performed using the SPSS 19, and level of significance was considered less than 0.05.
Results Comparison between healthy subjects and patients with IS at study onset (first day) ML CoP sway. In double standing, in one position (standing with closed eyes on a hard surface), p = 0.037, meaningful difference was seen between healthy subjects and patients with IS at study onset (first day). However, in standing on
dominant limb, there was no significant difference between the two groups in this parameter (Table 3). AP CoP sway. The average displacement of the CoP when scoliosis subjects stood on two feet compared to healthy subjects decreased except standing on the hard surface with closed eyes. There was significant difference in standing on two feet on a soft surface with opened eyes (p ⩽ 0.001) and with closed eyes (p = 0.013) between healthy and scoliosis subjects. In unilateral standing on dominant limb, there were significant differences between healthy and scoliosis subjects in standing on a soft surface with opened (p = 0.008) and closed eyes (p ⩽ 0.001) (Table 3). LoP of CoG in x-axis. In double standing, there was significant difference only on the hard surface with closed eyes in scoliosis subjects compared to healthy subjects in the LoP of the CoG (p = 0.012). However, in standing on dominant limb, there was no significant difference between the two groups in this parameter (p > 0.05) (Table 3).
Comparisons of CoP sway in subjects with IS in double standing CoP sway in ML axis. CoP sway in ML axis decreased in 4 months after wearing brace, while CoP sway increased in comparison between first day and 1 month after wearing brace. There was significant difference between 1 and 4 months after wearing brace (p 0.05).
Discussion Under normal conditions, balance is maintained predominantly by an ankle strategy to maintain CoP on the base of support. However, when there is a strong perturbation, a hip strategy is employed to maintain balance. Therefore, in situations like standing on unstable surfaces such as foam, or standing on one leg due to loss of support and ankle defects in sensory information for balance, strategy controls may not be sufficient, which causes the CoP sway to increase leading to instability.10 On the first day of the test, data reflected the weak balance of IS subjects compared to healthy subjects. The amount of CoP and CoG sway increased to keep balance especially when subjects stood on a foam surface with closed eyes. These observations share similarities to previous studies. Chen et al.17 in 1998 and Nault et al.6 in 2002 in a comparative study between healthy and scoliosis subjects showed patients with scoliosis have less balance than normal subjects, and if visual and proprioception systems are involved, scoliosis subjects adopt more trunk motion to maintain balance. Adler et al.15 found that scoliosis patients who wore a brace had better balance than patients who did not use a brace (tests were performed without the brace). The results suggest that wearing a brace might have a therapeutic effect on balance for patients with IS and despite reporting a negative impact on the balance with a brace, it may cause a long-term learning effect and a gradual improvement in balance performance.15 However, Sadeghi et al.24 in 2008 included 15 female patients with IS who had used a Boston brace. The 4-month follow-up study similar to our study follow-up showed that mean position of the CoP and the displacement were similar with and without braces. Nevertheless, in this study, after 1 and 4 months of wearing brace CoP and CoG sway
increased almost in all of the tests although there were no significant differences in all of the test conditions. However, the CoP sway in ML decreased after 4 months of wearing brace but in other variables CoP and CoG sway increased. The decrease in CoP sway in ML could be a result from the frontal curve correction, and the increase in CoG sway can result from enhancement of body sway for balance control. De Gauzy et al.20 in 2002 showed a similar result, and disruption of balance with thoraco lumbo sacral was seen. Therefore, in general, the brace did not deduct from the amount of CoP sway. Comparison between the results of 1 and 4 months of wearing brace showed that nearly in all of the test conditions, CoP sway area increased. These results could not indicate the learning effect of wearing brace after 4 months. Therefore, the authors concluded that the brace disrupted the balance in scoliosis patients. The limitations of this study were the period of extended evaluation which caused some of the subjects to withdraw, which in turn resulted in only girls participating. In this study, the CoP swing in ML, AP, and mean displacement of the CoG in the direction of the x-axis (LoP) in healthy and IS subjects were evaluated on the first day, 1 month, and 4 months after wearing brace. Future studies should therefore include the following: •• Study on the effect of brace on gait kinematics in individuals with scoliosis. •• The study of kinematic and kinetic parameters of wearing brace. •• Similar studies in both sexes in order to compare problems and therapeutic responses of girls and boys. •• Addition of various static and dynamic balance tests in order to generalize the results.
Conclusion In this study, it was found that IS subjects have poor (weak) balance in comparison to healthy subjects. Indeed, changes in processing of motor-sensory information or in sensory integration in IS subjects, causing more sway in their CoP, were attributed to a greater neuromuscular demand to maintain standing balance. In addition, wearing a brace for a period of 4 months did not produce an improvement in balance parameters in scoliosis subjects, and if vision is removed, caused further disturbance on the balance. The findings of this study indicate that there is a requirement to follow up the use and wear of orthoses in IS individuals. In particular, further studies need to focus on providing at least 1-year follow-up to identify the efficiency of brace on balance. Author contribution All authors contributed equally in the preparation of this article.
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Khanal et al. Declaration of conflicting interests The authors did not have any conflicts of interest with regard to the study presented in this article.
Funding This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
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