European Vertebral  Deviation Center - Clinique du Parc - Lyon (France)    Torsion

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SOSORT 2017

In-brace correction of Vertebral Rotation and Global Torsion: Case studies of 20 patients with AIS treated with the new Lyon ARTbrace

Abstract

Background: The detorsion of the ARTbrace is the consequence of the coupled movements of the spine correcting simultaneously the frontal and the sagittal plane of the 3 pelvic, lumbar and thoracic blocks. The design of the ARTbrace combines geometric and mechanical detorsion.

The aim of this study was to verify the immediate transverse plane in-brace correction with the ARTbrace.

Material and Methods: This was a retrospective case study of 20 patients with adolescent idiopathic scoliosis who had orthogonal AP and lateral X-rays before bracing and in-brace. An EOS 3D image of the spine was reconstructed. Axial spinal parameters were measured before bracing and then on the first post-brace X-ray: Maximal vertebra rotation, usually at the apex of the curve and global torsion which is the average of all the vertebral rotations included in the curvature.

All patients who were evaluated with 3D reconstruction were included.

Data were studied with the statistical package SPSS v20.

Results: Participants were 18 girls and 2 boys with an initial average Cobb angle of 33.3° (SD=11.04) and in-brace 6.05° (SD=9.75). The correction rate is 81.83%.

The initial average of Maximal Vertebra Rotation is 11.55° (SD = 7.81) and in-brace 5.52° (SD=7.02), with a correction rate of 52.16%.

The initial average of Global Torsion is 7.45° (SD = 5.24) and in-brace 3.72° (SD=5.25), with a correction rate of 50.07%.

Maximal Vertebra Rotation and Global Torsion were significantly correlated, r = .652, p = .002.

There was a nonsignificant correlation of r=.373 (p = .105) between detorsion and Cobb correction.

There was a nonsignificant correlation of r=.373 (p = .105) between detorsion and Cobb correction.

Primary results in the transverse plane are rarely published. The only significant result is that of (Lebel 2013), using also EOS, who shows that apical vertebra rotation was significantly improved by the Asymmetrical Chêneau brace compared to the Symmetrical Boston brace.

Conclusion: By utilizing the EOS 3D reconstruction technology, we can confirm that an asymmetrical brace like the new Lyon ARTbrace is really a Detorsion brace in the transverse plane. Deviations in the frontal and transverse plane are not correlated.

Background

Although we often talk about 3D Correction, primary results in the transverse plane are never published, or are considered non-existent, regardless of the measurement method used: MRI for Chu and EOS for Donzelli. [1,2] The only significant result is that of Lebel, using also EOS, who shows that following the brace treatment, apical vertebra rotation was significantly improved by the Asymmetrical polyethylene Chêneau type brace compared to the Symmetrical polyethylene Boston type brace [average change of 8.2 vs. 4.9, respectively (P = 0.02)]. [3]

The new Lyon ARTbrace is a detorsion brace adding geometrical (translation at both ends of the vertical axis) and mechanical detorsion on the outer surface of the torso. The detorsion of the ARTbrace is the consequence of the coupled movements of the spine correcting simultaneously the frontal and the sagittal plane of the 3 pelvic, lumbar and thoracic blocks during the digital cast. [4]

The aim of this study was to verify the immediate transverse plane in-brace correction in a sample of patients treated with the new Lyon ARTbrace.

I

Methods

Since 1998 all scoliotic patients are included in a monocentric prospective database for analytic observational study. This is a retrospective case study of 20 patients with adolescent idiopathic scoliosis who had orthogonal AP and lateral X-rays before bracing and in-brace. An EOS 3D image of the spine was reconstructed. Axial spinal parameters were measured before bracing and then on the first post-brace X-ray: Maximal vertebra rotation, usually at the apex of the curve and global torsion which is the average of all the vertebral rotations included in the curvature. Limit vertebrae are included in the Global Torsion. All patients who were evaluated with 3D reconstruction were included.  Written consent was obtained from the relative for publication of this study.

The initial X-ray is performed less than 3 months before ARTbrace and the in-brace X-ray, 3 days after the ARTbrace fitting.

All X-rays are measured by an independent radiologist trained in the EOS 3D protocol. [5]

An independent-samples t-test was conducted to compare Cobb angles before bracing and in-brace. Data were studied with the statistical package SPSS v20 with 95% confidence interval.

Results

20 patients (18 girls and 2 boys) were included with an initial average Cobb angle of 33.3° (SD=11.04) and in-brace 6.05° (SD=9.75). The correction rate is 81.83%.

The initial average of Maximal Vertebra Rotation is 11.55° (SD = 7.81) and in-brace 5.52° (SD=7.02), with a correction rate of 52.16%.

The initial average of Global Torsion is 7.45° (SD = 5.24) and in-brace 3.72° (SD=5.25), with a correction rate of 50.07%.

Maximal Vertebra Rotation and Global Torsion were significantly correlated, r = .652, p = .002.

There was a nonsignificant correlation of r=.373 (p = .105) between detorsion and Cobb correction.

There was a nonsignificant correlation of r=.373 (p = .105) between detorsion and Cobb correction.

Discussion

This work on a sample of patients with a good coronal Cobb correction rate of 82% was performed to better show the changes in the transverse plane. The correction rate in the transverse plane is less than the correction in the frontal plane (61%). The Maximal Vertebra Rotation is correlated with the Global Torsion. Both measure can therefore be used. The maximal vertebra rotation has the advantage of being measured on a frontal X-Ray by the Perdriolle torsiometer if the radiological enlargement is sufficient. [6]

The ARTbrace is a dynamic brace without pad inside. The only possible motion is at the junction of metal and polycarbonate and the induced shear promotes detorsion.

We were surprised to find that there is no correlation between the frontal plane and the transverse plane. There are frontal deviations without rotation and rotations without frontal deviations. That is why we prefer global detorsion to the classic 3-point system.

The horizontal correction being the consequence of the coupled movements in the frontal and the sagittal plane, we can consider that it is a variable compromise according to each scoliosis. The type of curvature can also influence the correction in the horizontal plane.


Conclusion

By utilizing the EOS 3D reconstruction technology, we can confirm that the asymmetrical ARTbrace is really a Detorsion brace in the transverse plane. The in-brace horizontal correction of 50% is the largest published to date. Deviations in the frontal and transverse plane are not correlated with the ARTbrace designed by a digital cast.

References

1. Chu WC, Wong MS, Chau WW, Lam TP, Ng KW, Lam WW, Cheng JC. Curve correction effect of rigid spinal orthosis in different recumbent positions in adolescent idiopathic scoliosis (AIS): a pilot MRI study. Prosthet Orthot Int. 2006 Aug;30(2):136-44.

2. Donzelli S, Zaina F, Lusini M, Minnella S, Respizzi S, Balzarini L, Poma S, and Negrini S. The three dimensional analysis of the Sforzesco brace correction. Scoliosis Spinal Disord. 2016; 11(Suppl 2): 34.

3. Lebel DE, Al-Aubaidi Z, Shin EJ, Howard A, Zeller R. Three dimensional analysis of brace biomechanical efficacy for patients with AIS. Eur Spine J. 2013 Nov;22(11):2445-8

4. de Mauroy JC, Lecante C, Barral F, Pourret S. Prospective study and new concepts based on scoliosis detorsion of the first 225 early in-brace radiological results with the new Lyon brace: ARTbrace. Scoliosis. 2014 Nov 19;9:19.

5. Glaser DA, Doan J, Newton PO. Comparison of 3-dimensional spinal reconstruction accuracy: biplanar radiographs with EOS versus computed tomography. Spine (Phila Pa 1976). 2012 Jul 15;37(16):1391-7

6. Perdriolle R, Vidal J. Thoracic idiopathic scoliosis curve evaluation and prognosis. Spine. 1985;10:785791


 

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