ABSTRACT

Objective:

To evaluate the axial correction capacity of the 3D brace in treating Adolescent Idiopathic Scoliosis (AIS).

Methods:

A retrospective study was carried out with 61 patients with AIS who obtained the 3D brace, between 2019 and 2022, in a laboratory that manufactures orthotics and orthopedic prostheses. These individuals underwent independent analysis of radiographic parameters by evaluating vertebral rotation using the Nash and Moe classification. The analyzed radiographs were taken in orthostasis before and after treatment with the 3D vest. Patients were divided into groups I and II-IV according to the Nash and Moe radiographic classification. Corrective capacity was estimated by assessing the degree of vertebral rotation before and after treatment.

Results:

Of the 61 patients evaluated, 36 (59%) had Nash and Moe grade I, and 25 patients grade II-IV before treatment. After treatment, 13 (21%) had grade II-IV, and 48 had grade I. Of the patients categorized as II-IV, 64% had improvement in the rotational profile. None clinical studies or radiographic parameter was associated with a change in rotational profile other than brace use (p=0.012).

Conclusion:

In the studied sample, treatment with the 3D vest promoted a change in vertebral rotation according to the Nash and Moe classification. The majority showed improvement in this parameter of evaluation of treatment of AIS. Level of Evidence III; Retrospective Study.

Keywords:
Scoliosis; Conservative Treatment; Analysis of Variance

RESUMO

Objetivo:

Avaliar a capacidade de correção axial do colete 3D no tratamento da Escoliose Idiopática do Adolescente (EIA).

Métodos:

Realizou-se estudo retrospectivo com 61 pacientes com EIA que obtiveram o colete 3D, entre 2019 e 2022, em um laboratório de confecção de órteses e próteses ortopédicas. Esses indivíduos foram submetidos à análise independente dos parâmetros radiográficos através da avaliação da rotação vertebral pela classificação de Nash e Moe. As radiografias analisadas foram realizadas em ortostase antes e após o tratamento com o colete 3D. Os pacientes foram separados em grupo I e grupo II-IV de acordo com a classificação radiográfica de Nash e Moe. A capacidade de correção foi estimada pela avaliação do grau de rotação vertebral antes e depois do tratamento.

Resultados:

Dentre os 61 pacientes avaliados, 36 (59%) apresentavam grau I, e 25 pacientes grau II-IV de Nash e Moe, antes do tratamento. Após o tratamento, 13 (21%) apresentavam grau II-IV e, 48 pacientes apresentavam grau I. Dos pacientes categorizados como II-IV, 64% tiveram melhora no perfil rotacional. Nenhum parâmetro clínico ou radiográfico estudado esteve associado com a mudança no perfil rotacional além do uso do colete (p=0,012).

Conclusões:

Na amostra estudada, o tratamento com o colete 3D promoveu mudança na rotação vertebral pela classificação de Nash e Moe. A maioria dos pacientes apresentou melhora neste parâmetro de avaliação de tratamento da EIA. Nível de Evidência III; Estudo Retrospectivo.

Descritores:
Escoliose; Tratamento Conservador; Análise de Variância

RESUMEN

Objetivo:

Evaluar la capacidad de corrección axial del corsé 3D en el tratamiento de la Escoliosis Idiopática del Adolescente (EIA).

Métodos:

Se realizó un estudio retrospectivo con 61 pacientes con EIA que obtuvieron el corsé 3D, entre 2019 y 2022, en un laboratorio que fabrica ortesis y prótesis ortopédicas. Estos individuos se sometieron a un análisis independiente de los parámetros radiográficos a través de la evaluación de la rotación vertebral utilizando la clasificación de Nash y Moe. Las radiografías analizadas se tomaron en ortostasis antes y después del tratamiento con el corsé 3D. Los pacientes se dividieron en grupo I y grupo II-IV según la clasificación radiográfica de Nash y Moe. La capacidad correctora se estimó evaluando el grado de rotación vertebral antes y después del tratamiento.

Resultados:

De los 61 pacientes evaluados, 36 pacientes (59%) tenían grado I de Nash y Moe, y 25 grado II-IV antes del tratamiento. Después del tratamiento, 13 (21%) tenían grado II-IV, y 48 grado I. De los pacientes categorizados como II-IV, el 64% tuvo mejoría en el perfil rotacional. Ningún parámetro clínico o radiográfico estudiado se asoció con el cambio en el perfil de rotación que no sea el uso de aparatos ortopédicos (p = 0,012).

Conclusiones:

En la muestra estudiada, el tratamiento con el corsé 3D promovió un cambio en la rotación vertebral según la clasificación de Nash y Moe. La mayoría mostró mejoría en este parámetro de evaluación del tratamiento de la EIA. Nivel de Evidencia III; Estudio Retrospectivo.

Descriptores:
Escoliosis; Tratamiento conservador; Análisis de Varianza

INTRODUCTION

The Milwaukee and Boston vests have been the most widely used orthoses in the conservative treatment of AIS over the last few decades.¹1 Rigo MD, Villagrasa M, Gallo D. A specific scoliosis classification correlating with brace treatment: description and reliability. Scoliosis. 2009;4(Suppl 2):O23. Both orthoses, due to their mechanism of action, do not act on vertebral rotation and tend to rectify the physiological curves in the sagittal plane, with the potential to produce what we know as flatback.²2 Gallo D, Wood G, Dallmayer R. Quality Control of Idiopathic Scoliosis Treatment in 147 Patients While Using the RSC® Brace. J Prosthet Orthot. 2011;23(2):69-77.,³3 Cheung J, Chong C, Cheung P. Underarm bracing for adolescent idiopathic scoliosis leads to flatback deformity: the role of sagittal spinopelvic parameters. Bone Joint J. 2019;101-B(11):1370-8.

Multi-planar correction vests first appeared in the early 1990s with the work of Chêneau. The Chêneau brace provided the biomechanical basis for multiplanar correction for other orthoses developed later, such as the Wood-Chêneau-Rigo (WCR^®),⁴4 Rigo M, Jelačić M. Brace technology thematic series: The 3D Rigo Chêneau-type brace. Scoliosis Spinal Disord. 2017;12:10. the Sforzesco, the Dynamic Derotation Braces (DDBs), S4D, etc. In Brazil, these orthoses are generically known as 3D vests, whose main purpose is to transfer multifocal corrective forces to the spine, acting on the scoliotic curve in the sagittal, coronal, and axial planes.²2 Gallo D, Wood G, Dallmayer R. Quality Control of Idiopathic Scoliosis Treatment in 147 Patients While Using the RSC® Brace. J Prosthet Orthot. 2011;23(2):69-77.,⁵5 Minsk MK, Venuti KD, Daumit GL, Sponseller PD. Effectiveness of the Rigo Chêneau versus Boston-style orthoses for Adolescent Idiopathic Scoliosis: a retrospective study. Scoliosis Spinal Disord. 2017;12:7. The 3D brace’s ability to correct vertebral rotation in the axial plane is a major advantage over the braces used in previous decades.⁶6 Kuklo TR, Potter BK, Lenke LG. Vertebral rotation and thoracic torsion n adolescent idiopathic scoliosis: what is the best radiographic correlate?. J Spinal Disord Tech. 2005;18(2):139-47. Controlling the rotation of the curve is fundamental to controlling the progression and imbalance of vertebral alignment.⁷7 Freitas Junior HO, França LCM, Castilho AM, Resende RLC de, Tavares PCM, Leal JS. Tratamento da Escoliose Idiopática com Colete Produzido com Tecnologia 3D. Coluna/Columna. 2021;20(3):174-80. However, to date, no study has evaluated the rotational corrective effect of the 3D brace.⁸8 Weinstein SL, Dolan LA, Wright JG, Dobbs MB. Effects of bracing in adolescents with idiopathic scoliosis. N Engl J Med. 2013;369(16):1512-21.

Therefore, this study aims to evaluate the effect of the 3D vest on vertebral rotation in patients with adolescent idiopathic scoliosis.

METHOD

Research design

A retrospective study was carried out to evaluate the effect of the 3D vest on the vertebral rotation of scoliotic curves in patients with AIS using the Nash and Moe method.

Ethics

This work is part of the EIA research line and was approved by our institution’s Research Ethics Committee, with the CAAE identification number: 44775621.1.0000.5128.

Place and period of the study

The study was carried out between January 2019 and January 2022 with patients diagnosed with AIS who came to an orthosis and prosthesis laboratory in Belo Horizonte-MG.

Main event

The main event of this study was the variation in the rotational profile of the apex of the scoliotic curve assessed by the Nash and Moe method before and after treatment with the 3D vest. The adjacent vertebra with the highest degree of rotation was used when the curve’s apex was in an intervertebral disc.

Secondary variables

The secondary variables studied were: gender, age, side of the convexity of the main curve, the apex of the main curve, location of the curve, type of curve, Risser classification, and magnitude. Table 1 describes the name and operational definition of each variable studied.

Sample

Sixty-two patients with AIS were admitted during the study period to evaluate the degree of vertebral rotation after using the vest. Of the 62 patients evaluated, one was excluded due to insufficient data or because he was not in the 10-17 age group. Sixty-one patients made up the final sample of this study.

Development of the study

We selected only patients diagnosed with AIS, aged between 10 and 17 years, who had panoramic anteroposterior radiographs of the spine in orthostasis taken before and after treatment with the 3D vest.

Two investigators collected data, both orthopedic surgeons who are members of the Brazilian Society of Orthopaedics and Traumatology. The degree of apical vertebral rotation using the Nash and Moe classification was identified using the tools in the Surgimap® software (Figure 1). The following secondary variables were then analyzed about scoliotic curves: apex of the main curve, location of the curve, type of curve, Risser classification, and magnitude. Risser’s sign has also been grouped into type A (0,1,2) and type B (3,4,5).⁹9 Souza MPM, Pereira AFF, Rangel TAM, Medeiros RC, Cabral LTB, Ferreira MAC, et al. Radiographical analysis of flexibility of idiopatic scoliosis in prono and supino. Coluna/Columna. 2020;19(1):13-7.,¹⁰10 Grivas T, Mauroy JC de, Wood G, Rigo M, Hresko MT, Kotwicki T, et al. Brace Classification Study Group (BCSG): Part one - definitions and atlas. Scoliosis Spinal Disord. 2016;11:43.

Data analysis

After selecting the data and radiographic images of the 61 patients, they were all classified according to Nash and Moe before the use of the 3D vest and immediately after its use, and a descriptive statistical analysis of the profile of the study participants was carried out. An association study of the secondary variables with the Nash and Moe classification change, stratified into two categories, was also carried out - grade I and grade II-IV categories of vertebral rotation.

The mean, standard deviation, median, quartiles, minimum and maximum were calculated to describe the continuous variables. For categorical variables, the absolute and relative frequency. The Chi-Square test and Student’s t-test were used to evaluate the change in classification. The analyses were carried out using Stata software version 16, and the tables were prepared using Microsoft Excel software (2019).

RESULTS

Tables 2 and 3 describe the characteristics of the sample studied. In this study, females predominated (81.97%), with the convexity of the curve to the right (57.38%). The apical vertebra was located in the thoracic region in 45.9% of patients, Risser category A in 59.02%, and double curve in 54.10%. The average age of the participants was 13.1 years.

Grade I vertebral rotation was predominant both before and after treatment. (Table 4)

Table 5 shows the frequency distribution of the variables studied according to categories I and II-IV of the Nash and Moe classification before using the 3D vest. The average age did not differ between the categories, with an average of 12.8 ± 1.6 in category I and 13 ± 1.9 in categories II-IV (p=0.196). The apex of the curve in the thoracic region predominated in rotation category I, while in categories II-IV, there was no predominance in the location of the apexes in the thoracic, thoracolumbar, and lumbar regions. Table 6 shows the frequency distribution of the variables studied according to categories I and II-IV of the Nash and Moe classification after using the 3D vest.

Table 7 compares the change in classification before and after wearing the vest (reduced: II♦I, III♦II, IV♦III, IV♦II; remained or increased: I♦I, I♦II, II♦II, III♦IV). The average age of the patients who had reduced spinal rotation was 13.8 ± 1.9, while the average age of those who had no change or increased the degree of rotation was 12.7 ± 1.6, with a statistically significant difference (p-value = 0.018).

Table 8 shows that of the 25 patients classified as category II-IV before using the 3D vest, 16 had a reduction in the degree of vertebral rotation after using the 3D vest and were now classified as category I, representing 64% of the patients (p=0.012). And of the 36 patients who were in Category I, four (11.1%) moved to Category II-IV.

DISCUSSION

The purpose of 3D vests is to correct scoliosis in all three planes of the deformity.⁴4 Rigo M, Jelačić M. Brace technology thematic series: The 3D Rigo Chêneau-type brace. Scoliosis Spinal Disord. 2017;12:10.,⁶6 Kuklo TR, Potter BK, Lenke LG. Vertebral rotation and thoracic torsion n adolescent idiopathic scoliosis: what is the best radiographic correlate?. J Spinal Disord Tech. 2005;18(2):139-47.,¹¹11 Wood G, Rigo M. The principles and biomechanics of the Rigo Chêneau type brace. In: Bettany-Saltikov J, Schreiber S. Innovations in Spinal Deformities and Postural Disorders. London: Intechopen; 2017. The correction in the axial plane seems to be the most notable feature of these vests, differentiating them from the Boston and Milwaukee vests. Freitas Junior et al., in a study of 138 patients treated with the 3D vest, demonstrated the corrective capacity in the coronal plane but did not evaluate the impact of these vests on rotation.⁸8 Weinstein SL, Dolan LA, Wright JG, Dobbs MB. Effects of bracing in adolescents with idiopathic scoliosis. N Engl J Med. 2013;369(16):1512-21. Other studies corroborate the effectiveness of these vests in the conservative treatment of scoliosis with curves between 20-45 degrees in terms of the magnitude of the curve measured by the Cobb degree in the frontal plane. Still, no study to date has demonstrated the effect of vertebral rotation of these vests in the treatment of scoliosis.¹1 Rigo MD, Villagrasa M, Gallo D. A specific scoliosis classification correlating with brace treatment: description and reliability. Scoliosis. 2009;4(Suppl 2):O23.,¹²12 Marawar SV, Ordway NR, Auston DA, Kurra S, Wang D. Simpson VM, et al. Assessment of Interand Intraobserver Reliability and Accuracy to Evaluate Apical Vertebral Rotation Using Four Methods: Na Experimental Study Using a Saw Bone Model. Spine Deform. 2019;7(1):11-7.

This study evaluated the effect of the 3D vest on spinal rotation in a retrospective analysis involving 61 patients, with the measurement of the degree of rotation assessed by the Nash and Moe classification as the main outcome. The Nash and Moe system is the most widely used method for assessing vertebral rotation in daily orthopedic practice.¹³13 Marawar SV, Ordway NR, Auston DA, et al. Assessment of Interand Intraobserver Reliability and Accuracy to Evaluate Apical Vertebral Rotation Using Four Methods: Na Experimental Study Using a Saw Bone Model. Spine Deform. 2019;7(1):11-7. The results showed that 64% of patients categorized as grade II-IV significantly reduced the degree of vertebral rotation, indicating a possible defeat effect in curves with higher degrees of vertebral rotation (p=0.018). On the other hand, in patients with grade I, 11.1% of them had an increase or no change in vertebral rotation. The data collected in this study did not allow us to identify the possible causes of increased or unchanged vertebral rotation. The progression of rotation or absence of change in grade I can be attributed, albeit speculatively, to the low reliability of the Nash and Moe classification, to a possible initial progression, or the failure of treatment with the vest in this group.

This study has limitations. This is a retrospective study in which the main event studied was vertebral rotation, the assessment of which undergoes variations related to image quality, anatomical variations of the scoliotic vertebrae, and factors inherent to the reliability of the Nash and Moe classification.¹³13 Marawar SV, Ordway NR, Auston DA, et al. Assessment of Interand Intraobserver Reliability and Accuracy to Evaluate Apical Vertebral Rotation Using Four Methods: Na Experimental Study Using a Saw Bone Model. Spine Deform. 2019;7(1):11-7. Intraand inter-observer variations in the classification are only known in controlled radiographs taken on biomechanical test specimens.¹³13 Marawar SV, Ordway NR, Auston DA, et al. Assessment of Interand Intraobserver Reliability and Accuracy to Evaluate Apical Vertebral Rotation Using Four Methods: Na Experimental Study Using a Saw Bone Model. Spine Deform. 2019;7(1):11-7. Furthermore, this study did not compare the defeating effect of the 3D vest with the Boston or Milwaukee vests. Another important limitation was the one-off assessment of the vest’s immediate defeating effect on the first control X-ray after starting treatment. The study suggests some defeating effects on turns with higher degrees of rotation while wearing the vest. Although this immediate defeating effect is positive in the conservative treatment of scoliosis, nothing can be concluded about its long-term effect, especially after you stop using it. It is unknown whether the gain in the rotation is definitive or transitory, nor the importance of rotational control with the 3D vest in the long-term results of conservative scoliosis treatment. The authors of this study are conducting a long-term line of research aimed at analyzing the results after discontinuing the use of the vest. Comparative prospective studies are needed to shed light on this relatively new form of conservative treatment for scoliosis.

CONCLUSION

The results of this study demonstrate an immediate defeating effect on the apical vertebra in the treatment of idiopathic scoliosis using the 3D vest. Further studies are needed to assess its long-term effect after discontinuing the vest use.

REFERENCES

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