The effectiveness of Schroth exercises added to the brace on the postural control of adolescents with idiopathic scoliosis: Case series

Abstract

Background

One of the disorders that may cause changes in body posture and impair postural control is adolescent idiopathic scoliosis (AIS). Scoliosis-specific exercises, such as the three-dimensional Schroth method added to the brace, may be able to help these patients improve their postural control. The aim of this study was evaluating the effect of Schroth physiotherapy scoliosis-specific exercises added to the brace on AIS patients' postural control.

Patients and methods

It is a case series study on twenty-three AIS patients. They were treated using the Schroth method and brace for three months, with the first five sessions lasting two weeks and subsequently one session per week. Postural control assessments include center of pressure (COP) range and COP velocity in the anteroposterior (AP) and mediolateral (ML) directions, and the COP sway area in the standing position with opened eyes and closed eyes by the force plate. The angle of trunk rotation (ATR) was assessed by the scoliometer. The methods are consistent with the PROCESS 2020 guidelines.

Results

The Schroth method and brace also significantly improved the variables of postural control variables in terms of COP range (p < 0.001), COP velocity (p < 0.001), and COP sway area in standing positions with opened and closed eyes (p < 0.001, p < 0.001) as well as ATR (p < 0.001) in AIS patients.

Conclusion

Schroth method and brace improved the postural control and trunk rotation of AIS patients.

Highlights

• •Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformity of the spine that affects postural control.
• •Schroth method is based on the three-dimensional corrective principles.
• •Schroth method and brace improved the postural control of AIS patients.
• •Trunk rotation was reduced by Schroth method and brace.

1. Introduction

Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformity of the spine that affects the shape and condition of the chest and trunk [1]. The cause of scoliosis has not yet been recognized and is being sought in inherited or acquired disorders of the spinal structure [2,3]. The prevalence of AIS with a Cobb angle greater than 10° is 0.93–12% [4,5], and its incidence varies according to geographical location [5,6].

If the progression of scoliosis is not prevented and treated in order to improve it, it can lead to problems such as limitations in the biomechanical function of the chest, changes in body posture, and defects in postural stability [7,8]. Biomechanical changes include deviations in the curvature of the spine and changes in the direction of the head, shoulders, scapula, and pelvis in three planes, which may lead to impaired postural stability [9], and this disorder in postural control is more pronounced in the trunk [10,11]. Changes in the relationship between body segments and muscle imbalances on both sides of the spine affect muscle function. Achieving a completely vertical position is also impaired in scoliosis, resulting in changes in the center of mass (COM), so that the torque of the corrective muscles in the trunk and lower limbs is necessary to maintain the stability of the body [12]. Perceptions and interpretations of sensory stimuli in AIS appear to have changed, interfering with the choice of appropriate motor response [12]. Consequently, scoliosis is associated with changes in mediolateral (ML) and anteroposterior (AP) position, as well as the sway area and velocity of the COM [13]. A set of center of pressure (COP) control variables and spinal posture have also been found to have a substantial association [14]. This indicates that the postural stability of scoliosis patients is weaker than that of a healthy control group of comparable age [[15], [16], [17]].

So far, various therapies such as braces, traction, biofeedback, exercise, and surgery have been used to treat AIS [1,18]. Society on Scoliosis Orthopedic and Rehabilitation Treatment (SOSORT) recommends specific scoliosis exercises as a standard treatment at angles less than 45° next to the brace [1,19,20]. There are various exercises for scoliosis, including the Schroth treatment [21]. The three-dimensional corrective principles of the Schroth method include auto elongation, deflection, derotation, rotational breathing, and stabilization. In this method, muscle activation is achieved by activating some muscles that will help improve spinal correction, such as iliopsoas, quadratus lumborum, latissimus dorsi, and erector spinae [22]. The patient also learns to correct spinal deformity through the help of sensory-motor feedback mechanism and corrective breathing patterns. In this breathing pattern, the patient directs the inhaled air to the concave area of the chest, and the ribs move in a convex direction with selective contraction of the trunk [22,23]. The effectiveness of Schroth treatment in reducing the Cobb angle has been demonstrated in recent studies [24,25].

Since scoliosis is associated with changes in mediolateral (ML) and anteroposterior (AP) position, as well as the sway area and velocity of the COP [13], and torque of the corrective muscles in the trunk and lower limbs [26], and as the Schroth method focuses on three-dimensional posture correction [22,23], the purpose of this study was to evaluate the effect of Schroth treatment method and brace on the control of static balance in patients with AIS.

2. PATIENTS and METHODS

2.1. Study design

This study was a case series on AIS patients that was performed in the biomechanics laboratory and physiotherapy clinic of the Department of Physiotherapy, Faculty of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, Iran, between December 2019 and January 2021. The proposal of this study was approved by the ethics committee of Iran University of Medical Sciences on November 4, 2019 (IR.IUMS.REC.1398.804) and was registered in the Iranian Registry of Clinical Trial (IRCT20180728040618N3). This study was also registered to www.researchregistry.com (unique identifying code: researchregistry 8374). Before starting the study and after getting acquainted with the process and objectives of the study, informed consent was obtained from the participants and their parents in writing and orally. Our work has been reported in line with the PROCESS guideline [27]. Agha RA, Sohrabi C, Mathew G, Franchi T, Kerwan A, O'Neill N for the PROCESS Group. The PROCESS 2020 Guideline: Updating Consensus Preferred Reporting Of Case Series in Surgery (PROCESS) Guidelines, International Journal of Surgery 2020; 84:231–235.

2.2. Participants

Patients in this study were adolescents in whom AIS was diagnosed by a spine surgeon. The criterion for naming and classifying curvature of AIS patients in this study was based on the Schroth method. Inclusion criteria for AIS patients included: diagnosis of AIS, the age range of 10–18 years, a Cobb angle of 10–45°, main curvature in the right thoracic spine, a Risser sign of 0–5, no treatment during this study, which affects scoliosis, and the ability to attend weekly visits. AIS patients were excluded from the study if they had contraindications to exercise, mental health disorders, neuromuscular or rheumatic diseases, a history of spinal surgery, a surgical schedule, and nonidiopathic scoliosis. The characteristics of AIS patients are summarized in Table 1. Prior to the intervention and evaluation of posture control, patients were examined for joint pain, other musculoskeletal disorders, and other medical conditions.

Table 1.

Patients’ characteristics.

Subject no.	Age	Sex	Risser sign	Cobb angle	Compensatory curve	Angle of trunk rotation
1	12	Female	1	25	No	11.89
2	11	Female	1	21	No	9.74
3	11	Female	1	24	left thoracolumbar	10.05
4	10	Female	1	31	No	13.87
5	12	Female	2	27	No	11.02
6	12	Female	1	29	No	12.84
7	13	Female	3	25	left lumbar	11.09
8	13	Male	2	27	No	12.93
9	14	Female	3	33	left thoracolumbar	13.33
10	15	Female	3	35	left lumbar	15.87
11	11	Male	1	37	No	17.21
12	13	Female	2	28	No	11.50
13	14	Female	2	26	left lumbar	10.36
14	12	Female	1	19	No	8.64
15	11	Female	1	28	No	12.45
16	13	Female	3	39	No	19.66
17	14	Male	3	26	left lumbar	11.54
18	13	Male	2	27	left lumbar	12.33
19	11	Female	2	35	No	17.39
20	15	Male	3	35	No	16.24
21	12	Female	1	29	No	12.88
22	12	Female	1	32	No	13.86
23	12	Female	1	31	No	13.79

The sample size of this study in AIS patients was determined based on a pilot study (initial n = 8) using the G*Power Statistical Package (version 3.0.10) with an α value of 0.05 to achieve a statistical power of 0.80 and an effect size of 0.69. This was the smallest effect size of variables based on the mean and standard deviation of the COP range (COPr) in AP direction in standing position with opened eyes (21.83 ± 4.50 for pre-test and 18.81 ± 4.15 for post-test), which required a minimum sample size of 19. Considering the drop-out rate of 20% and aiming to increase the statistical power of the results, 23 AIS (18 girls and 5 boys) were recruited into the study.

2.3. Interventions

The course of treatment consisted of five 60-min sessions in the first two weeks of training and practice, followed by one weekly session for three months under the supervision of a physiotherapist at the clinic, with 30–45 min of daily exercises at home (Fig. 1). The intensity of the exercise program was gradually increased according to the performance improvement of each participant. During these three months, all patients wore a Boston brace for at least 16 h each day, according the spine surgeon's prescription, and the brace was removed during Schroth exercises. Therapeutic interventions were performed by a physiotherapist with five years of experience in treating AIS with the Schroth method and with an internationally recognized certificate from the Best Practice Schroth Institute.

Fig. 1.

Schroth physiotherapy specific exercises: A, 50X; B, Door handle; C, Muscle cylinder; D, Rotational sitting; E, 3D made easy.

Treatment adherence was measured as a percentage of the specified treatment sessions performed over the course of three months, and compliance was measured as a percentage of the number of exercises prescribed. Parents examined compliance control on a daily basis, and a physiotherapist reviewed compliance control on a weekly basis, using a logbook comprising a daily exercise schedule.

2.4. Measurements

Demographic information (age, sex, weight, height, BMI) was collected during interviews with participants. Cobb angle and angle of trunk rotation (ATR) were assessed by the spinal surgeon.

Postural control: A force plate (Kistler Group-Swiss, 40*60 cm, (Type: 5691 A)) was used to collect static balance variables. Data were collected at 100 Hz and filtered at 10 Hz (low pass Butterworth). The COP range (COPr) and COP velocity (COPv) in the anteroposterior (AP) and mediolateral (ML) directions were determined as postural control variables. The COP sway area (COPsa) was calculated as a 95% confidence ellipse area [28].

Angle of trunk rotation: The ATR was assessed with the scoliometer and Adam's forward bend test. Patients were asked to bend forward, and ATR (the angle between the horizontal plane and the plane passing through the posterior part of the trunk) was measured using the apical vertebrae of the curve and the maximum angle of trunk rotation was recorded [29].

2.5. Protocol

AIS patients were asked to stand on the force plate with their arms at their sides. As suggested by Dufvenberg et al. participants were placed at a distance of 23 cm and at an angle of approximately 30° on the support surface. AIS patients were advised to breathe normally and look directly at the white spot 1.2 m away at eye level [30]. The static test lasted 20 s and was performed in two conditions with opened eyes (OE) and closed eyes (CE) randomly. All tests accomplished out of brace. Each condition was tested three times, with a 2-min break between each test.

2.6. Statistical analysis

Statistical analysis was performed using IBM® SPSS (version 21.0 software, IBM Corp., Armonk, NY, USA). Descriptive statistics were calculated for baseline demographics for the entire sample. The Shapiro-Wilk test was used for normality of all variables. Nonparametric Wilcoxon test was performed statistically for comparing postural control variables and ATR before and after the intervention of Schroth method and brace in AIS patients. Cohen's d effect size index was used for each of the dependent variables after the intervention. Statistical significance was determined at a p value of <0.05.

3. Results

This study included 23 AIS patients for comparing the efficacy of Schroth method and brace on postural control in standing position with OE and CE. The mean age (year), weight (kg), height (m), and BMI (kg/m²) of the participants were 12.40 ± 1.27, 48.03 ± 9.06, 1.60 ± 0.11 and 18.51 ± 1.94, respectively. Other basic information about patients' conditions, including age, sex, Risser sign, Cobb angle, type and level of curvature, ATR are shown in Table 1.

The comparison between the mean values of postural control variables in OE and CE, and ATR of AIS before and after three months of treatment in OE and CE are shown in Table 2.

Table 2.

Comparison of mediolateral (ML) and anteroposterior (AP) center of pressure range (COPr), velocity (COPv), and sway area (COPsa) with closed eyes (CE) and opened eyes (OE), between before intervention (BI) and after intervention (AI) for adolescent idiopathic scoliosis (AIS). Also, comparison of angle of trunk rotation (ATR) for adolescent idiopathic scoliosis between BI and AI.

Variables			AIS-BI	AIS-AI	Pre-post difference in change scores	p AIS-AI vs. AIS-BI	Effect size
			Mean ± SD	Mean ± SD	Mean (95%CI)		Cohen's d
CE	COPr (mm)	ML	21.62 ± 6.09	15.96 ± 5.33	5.65	0.001	0.98
					(3.04, 8.26)
		AP	31.54 ± 11.08	23.96 ± 8.75	7.57	0.002	0.75
					(2.57, 12.57)
	COPv (mm/s)	ML	10.18 ± 3.25	7.81 ± 3.22	2.36	0.001	0.73
					(1.21, 3.51)
		AP	15.34 ± 4.60	12.96 ± 6.46	2.38	0.004	0.42
					(-0.25, 5.01)
	COPsa (m2)		554.86 ± 213.52	372.53 ± 339.31	182.33	0.005	0.64
					(48.38, 316.27)
OE	COPr (mm)	ML	18.82 ± 5.31	14.89 ± 5.14	3.93	0.024	0.75
					(0.75, 7.10)
		AP	24.03 ± 5.60	20.40 ± 5.74	3.62	0.018	0.64
					(0.69, 6.55)
	COPv (mm/s)	ML	8.37 ± 1.99	6.50 ± 2.62	1.87	0.001	0.80
					(0.99, 2.75)
		AP	12.23 ± 3.47	9.62 ± 3.71	2.61	0.003	0.72
					(1.14, 4.07)
	COPsa (m2)		412.72 ± 162.52	256.99 ± 145.45	155.73	0.003	1.01
					(62.55, 248.91)
____	ATR (°)		13.06 ± 2.70	11.14 ± 2.87	1.92	0.001	0.68
					(1.23, 2.60)

SD: Standard deviation.

There was a statistically significant difference in postural control variables before and after three months of therapeutic exercises. The COPr before treatment in the OE standing position in the ML and AP directions were 18.82 ± 5.31 and 24.03 ± 5.60, respectively, compared to 14.89 ± 5.14 and 20.40 ± 5.74 after treatment (p = 0.024, p = 0.018). Also, the COPr before treatment in the standing position with CE in the directions of ML and AP were 21.62 ± 6.09 and 31.54 ± 11.08, respectively, compared to 15.96 ± 5.33 and 23.96 ± 8.75 after treatment (p = 0.001, p = 0.002). The COPv before treatment in the standing position with OE in the ML and AP directions were 8.37 ± 1.99 and 12.23 ± 3.47, respectively, compared to 6.50 ± 2.62 and 9.62 ± 3.71 after treatment (p = 0.001, p = 0.003). Also, the COPv before treatment in the standing position with CE in the directions of ML and AP were 10.18 ± 3.25 and 15.34 ± 4.60, respectively, compared to 7.81 ± 3.22 and 12.96 ± 6.46 after treatment (p = 0.001, p = 0.004). There was a significant difference in the COPsa in OE and CE positions before and after treatment (p = 0.003, p = 0.005). The COPsa before treatment in the standing position with OE and CE was 412.72 ± 162.52 and 554.86 ± 213.52, respectively, compared to 256.99 ± 145.45 and 372.53 ± 339.31 after treatment.

There was a statistically significant difference in comparison between before and after treatment according to ATR (p = 0.001), and the mean of ATR decreased from 13.06 ± 2.70° to 11.14 ± 2.87°.

4. Discussion

This study showed that the Schroth method and brace also significantly improved the variables of postural control variables in terms of COP range, COP velocity, and COP sway area in standing positions with opened and closed eyes as well as ATR in AIS patients. The results of this study seem to be consistent with the hypothesis of this study.

These findings can be explained based on two perspectives. In the first view, according to the hypothesis of sensory integration, individuals with AIS have difficulty in the central processing of balance control, and the position of COP relative to COM cannot be readjusted, which ultimately leads to increased body oscillation [8,9]. Trunk rotation, lateral curvature of the spine (even with mild curvature), and lastly, COM displacement all need more neuromuscular effort and potentially compromise stability [31]. The therapeutic method of Schroth does not seem to be able to improve balance disorder directly by affecting the central nervous system. The second explanation for balance disorder in AIS is the biomechanical hypothesis, which emphasizes morphological changes and deviations in the normal direction of the curvature of the spine in three dimensions [9,32]. In other studies, Burwell et al. [33], Goldberg et al. [34], and Ramirez et al. [35] have found a strong association between spinal deformity and asymmetric posture, which reinforces the idea of biomechanics. The findings of Pasha et al. [14] point to the strong correlation between postural variables and balance. It also recommends that this correlation be considered to guide therapies such as Schroth method, which is for spinal correction. In our study, the use of Schroth method and brace for three months was able to improve balance control. The results of this study contradict the findings of Bidari et al. that showed the use of the Blount and Moe exercise protocol did not affect balance [36]. The design of that investigation was cross-sectional. Seventeen brace users were divided into 3 groups (good, moderate, and weak) based on the quantity and quality of their activity. The participant and one of the parents were asked retrospectively about their average weekly hours of exercise over the previous year. Up to the weaning phase, the quantity and quality of exercise in conjunction with bracing has no effect on static balance and changes in scoliosis and kyphosis. Although these exercises are designed to correct curves, they focus on the pelvic tilt and may not be able to change the direction of the segments, and as a result, they may not be effective in improving balance.

Our improvements to ATR are consistent with those shown in the study by Kuru et al. On forty-five AIS patients, they designed a randomized clinical trial research. There were three groups of patients. The first group received Schroth's 3D exercises in the clinic, while the second group received them as a home exercise program; the third group served as the control. The first and second groups did these exercises for a total of 24 weeks. The Schroth exercise program done in the clinic under the supervision of a physiotherapist was better than the home exercise and control groups at reducing ATR. In a randomized clinical trial enrolling 28 AIS patients with mild curvature, Kocaman et al. [37] demonstrated that ten weeks of short-term Schroth technique training is more beneficial than core stability exercises in lowering ATR. In addition, Kwan et al. [38] found in a prospective, historical cohort-matched investigation that Schroth exercises and braces reduced ATR. However, decrease of ATR was observed in the Schroth exercise and brace group, this change was not statistically significant compared to the group that received only braces. It has been shown that there is a relationship between ATR, and the magnitude of the curvature and it directly affects the Cobb angle [39].

Since scoliosis patients have impaired postural control, any therapeutic exercise that simultaneously enhance spine alignment and postural control may be more helpful in treating scoliosis. Therefore, it is possible to determine the effect of various specific scoliosis exercises and braces on posture management in randomized clinical trial study.

There are several limitations to this study that should be noticed, such as the small sample size, which limits the generalizability of the study. In addition, the effect of Schroth method and brace on postural control was examined only in the static standing position and without control group. It is recommended that further examinations be done on the effect of Schroth method and brace on the stability of dynamic standing position and walking, which challenge the balance more.

In conclusion, based on the findings of this study, it can be concluded that Schroth exercises and brace reduce ATR, and improve postural control in AIS patients.

Funding

The authors received no financial support for the research and/or authorship of this article.

Ethical approval

The ethical committee of Iran University of Medical Sciences approved the study (Ethical code: IR.IUMS.REC.1398.804).

Consent

Before starting the study and after getting acquainted with the process and objectives of the study, informed consent was obtained from the participants and their parents in writing and orally.

Author contribution

Study concept or design: YL, HM; Data collection: YL; Data analysis or interpretation: RS, HGH; Writing the paper: YL, HM, RS.

Guarantor

Yasin Larni.

Declaration of competing interest

The authors declare no conflict of interest.