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Development of CAD/CAM Based Brace Models for the Treatment of Patients with Scoliosis-Classification Based Approach versus Finite Element Modelling

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Hans-Rudolf Weiss at Schroth Best Practice Academy
Hans-Rudolf Weiss
  • Schroth Best Practice Academy
Alexander Kleban at Lomonosov Moscow State University
Alexander Kleban
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Abstract

Study design: Retrospective controlled cohort study comparing the in-brace correction of two samples of scoliosis patients with braces of different computer aided design (CAD). Purpose: In-brace correction and compliance correlate with outcome. The more standardized CAD braces that are available should enable improved in-brace correction and outcome. This study compared recent CAD brace developments with respect to in-brace corrections. Overview of literature: A 2013 randomized controlled trial demonstrated that 72% of a population complying to Scoliosis Research Society inclusion criteria on bracing did not progress using braces (mainly Boston braces) used in the United States and Canada with moderate corrective effect. Methods: In-brace corrections achieved in a sample of patients fulfilling the inclusion criteria for studies on bracing using the classification based approach (CBA) were compared to the recent individual CAD/computer aided manufacturing bracing based on finite element modelling approach (FEMA). Results: In-brace corrections using the different approaches differed widely. CBA in-brace corrections were 66% of the initial value. FEMA in-brace correction was 42% of the initial value. Conclusions: Considering the fact that in-brace correction (and compliance) determines the end result of bracing in the treatment of scoliosis, scoliosis braces based on CBA are superior to the FEMA and the standard plaster based brace applications.
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Development of CAD/CAM based brace models
Asian Spine JournalAsian Spine Journal
661
Copyright Ⓒ 2015 by Korean Society of Spine Surgery
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Asian Spine Journal • pISSN 1976-1902 eISSN 1976-7846 • www.asianspinejournal.org
Received Jan 29, 2015; Revised Mar 25, 2015; Accepted Mar 25, 2015
Corresponding author: Hans-Rudolf Weiss
Orthopaedic Rehabilitation Services, Gesundheitsforum Nahetal, Alzeyer Str. 23, Gensingen D-55457, Germany
Tel: +49-6727-894040, Fax:+49-6727-8940429, E-mail: hr.weiss@skoliose-dr-weiss.com
Development of CAD/CAM Based Brace
Models for the Treatment of Patients with
Scoliosis-Classication Based Approach versus
Finite Element Modelling
Hans-Rudolf Weiss1, Alexander Kleban2
1Orthopaedic Rehabilitation Services, Gesundheitsforum Nahetal, Gensingen, Germany
2Department of Mathematics, Lomonosov Moscow State University, Moscow, Russia
Study Design: Retrospective controlled cohort study comparing the in-brace correction of two samples of scoliosis patients with
braces of different computer aided design (CAD).
Purpose: In-brace correction and compliance correlate with outcome. The more standardized CAD braces that are available should
enable improved in-brace correction and outcome. This study compared recent CAD brace developments with respect to in-brace cor-
rections.
Overview of Literature: A 2013 randomized controlled trial demonstrated that 72% of a population complying to Scoliosis Research
Society inclusion criteria on bracing did not progress using braces (mainly Boston braces) used in the United States and Canada with
moderate corrective effect.
Methods: In-brace corrections achieved in a sample of patients fullling the inclusion criteria for studies on bracing using the clas-
sication based approach (CBA) were compared to the recent individual CAD/computer aided manufacturing bracing based on nite
element modelling approach (FEMA).
Results: In-brace corrections using the different approaches differed widely. CBA in-brace corrections were 66% of the initial value.
FEMA in-brace correction was 42% of the initial value.
Conclusions: Considering the fact that in-brace correction (and compliance) determines the end result of bracing in the treatment of
scoliosis, scoliosis braces based on CBA are superior to the FEMA and the standard plaster based brace applications.
Keywords: Scoliosis; Brace; Orthothis; Correction; Computer aided design
Basic Study Asian Spine J 2015;9(5):661-667 • hp://dx.doi.org/10.4184/asj.2015.9.5.661
ASJASJ
Asian Spine JournalAsian Spine Journal
Introduction
Scoliosis is a lateral deviation of the spine commonly
exhibiting different patterns of curvature [1]. The basic
curve patterns are named aer the location of the major
curve (e.g., thoracic, lumbar, thoracolumbar, double ma-
jor, and double thoracic), but other specic classications
have been described [2]. In structural scoliosis, there is
usually a certain amount of spinal torsion and a distur-
bance of the sagittal prole coupled to the lateral defor-
Hans-Rudolf Weiss et al.662 Asian Spine J 2015;9(5):661-667
mation [1]. erefore, scoliosis must be more accurately
regarded as a three-dimensional (3D) deformity of the
spine and trunk, which may progress quickly during peri-
ods of rapid growth [1].
ere is some evidence for the use of physiotherapy in
the treatment of patients with spinal deformities. Howev-
er, during the pubertal growth spurt (high-risk phase for
progression), brace treatment is the most important mode
of treatment [1]. In-brace correction and compliance cor-
relate with outcome [1,3]. More asymmetric braces with
increased corrective eect are preferable (Cheneau style)
to the more symmetric Boston braces [1,3].
Historically, the Boston brace treatment has produced
brace corrections exceeding 30% of the initial angle of
curvature. For Cheneau braces, as early as 1985 brace cor-
rections exceeding an average of 40% have yielded bene-
cial end-results. Recent in-brace corrections with rened
Cheneau derivates have reportedly exceeded 50% of the
initial value. While the Cheneau brace has historically
been constructed only by modifying the plaster positive
of the individual patient (Fig. 1), the Boston brace was
constructed by modication of a plaster cast individually
or by adjustment of a formerly provided prefabricated
Boston module.
e Boston brace is now regarded as the baseline stan-
dard for new individual computer aided design/computer
aided manufacturing (CAD/CAM) braces [4-9]. Finite
element modelling results have suggested that individual
braces can be constructed using CAD to correct individual
curvature patterns when low-dose stereo X-rays are avail-
able for calculation. is approach seems very promising,
as it addresses very precisely curve patterns individually
and not by classification. However, in-brace corrections
still do not reach the percentage correction attained with
Cheneau applications [6,9].
Cheneau applications can also be constructed by CAD/
CAM [1,2]. These applications are not based on finite
element modelling, but instead on specic classications
of curve patterns developed empirically (Fig. 2) [2]. e
original Cheneau brace was derived from the Abbott
model of correction [10]. Voids are implemented opposite
to the pressure zones in all 3D to allow the 3D corrective
movement without compression of the patient. This has
lead to semi-standardized, custom-made braces for func-
tional 3- and 4-curve patterns [10]. is simple Cheneau
classication is based on the version implemented about
a half-century ago [10]. is simple classication remains
relevant for present-day physiotherapy treatment of sco-
liosis. However, more specic bracing classications have
been established.
The most recent classification for bracing scoliosis,
the augmented Lehnert-Schroth classification (Fig. 2),
derived from the original Lehnert-Schroth classication.
The present publication provides a description of the
empirically based CAD/CAM brace model (classication
based approach, CBA), which incorporates the collective
information obtained over nearly 4 decades preceeding
the actual CAD/CAM Cheneau derivates [2].
An ongoing prospective controlled trial is comparing
this approach to other samples described in literature us-
ing the Scoliosis Research Society (SRS) inclusion criteria
for studies on bracing. A recent publication described in-
Fig. 1. Plaster based brace construction according to the Cheneau principles.
Development of CAD/CAM based brace models
Asian Spine JournalAsian Spine Journal
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brace corrections achieved using the nite element mod-
elling approach (FEMA) [11]. So, the in-brace corrections
achieved in the sub-sample of patients fulfilling SRS in-
clusion criteria for studies on bracing using the CBA [2]
can be compared to the individual CAD/CAM bracing
approach based on FEMA.
Materials and Methods
Within the CBA, seven basic patterns of curvature (Figs.
2–4) were established as a subclassification to the origi-
nal Lehnert-Schroth classication (3- and 4-curve). Two
additional patterns were introduced to address double
thoracic curvatures and a thoracolumbar pattern with a
structural high thoracic counter curve. In 2011, we com-
menced a prospective controlled study on CBA outcome
using the SRS inclusion criteria involving all patients
available at that time, with the aim of testing the in-brace
correction achieved. Twenty-one patients fulfilled the
SRS inclusion criteria on bracing. e average Cobb cur-
vature angle and in-brace Cobb angle was 31° and 11°,
respectively. Concerning FEMA [11], until recently there
were no consistent results regarding the published in-
brace correction [9]. The in-brace corrections achieved
using FEMA could derived from a sample of 15 patients
reported on recently [11]. We statistically compared the
average in-brace corrections as achieved with the two dif-
ferent approaches. e Student t-test was used to compare
the in-brace corrections of the two dierent samples.
Fig. 2. The Augmented Lehnert-Schroth classication used for the selection of the appropriate brace from Gensingen library. 3CH, 3-curve
with hip prominence; 3CTL, 3-curve with hip prominence thoracolumbar; 3C, 3-curve balanced; 3CL, 3-curve with long lumbar counter-
curve; 4C, 4-curve double; 4CL, 4-curve single lumbar; 4CTL, 4-curve single thoracolumbar. Reprinted from Weiss et al. [2], according to the
Creative Commons License of OA Publishing London.
Fig. 3. The seven basic models of the Gensingen library. Model (A)
3BH, (B) 3BTL, (C) 3BN, (D) 3BL, (E) 4B, (F) 4BL, (G) 4BTL. 3B, func-
tional 3 curve pattern; 4B, functional 4 curve pattern. Reprinted from
Weiss [12], according to the Creative Commons License of OA Publish-
ing London.
A B C D
E F G
Hans-Rudolf Weiss et al.664 Asian Spine J 2015;9(5):661-667
Results
CBA analyses involved 21 females who matched the SRS
inclusion criteria for studies on bracing. eir average age
was 12.2 years (standard deviation [SD], 1.1 years). The
distribution of curve patterns was thoracic (n=11), double
major (n=4), lumbar (n=4), and thoracolumbar (n=2).
e average Risser stage was 0.38 (SD, 0.68) and the av-
erage Cobb angle was 31.33° (SD, 6.58°). Concerning
FEMA, the average Cobb angle prior to bracing for the
15 patients was 31° for the main thoracic (MT) curve and
32° for the thoracolumbar/lumbar (TL/L) curve. e New
Brace (FEMA) reduced Cobb angles by 42% (39% for the
MT curve and 49% for the TL/L curve), which were pre-
dicted with a dierence inferior to 5° by the simulation.
e standard brace (Boston type) reduced these angles by
43% [11]. In-brace corrections diered widely when the
dierent approaches were compared. In-brace corrections
in the CBA was 66% of the initial value and in-brace cor-
rection in the FEMA was 42% of the initial value when
not wearing the brace. Statistical comparison of the extent
of in-brace corrections of CBA (sample derived from [2])
with FEMA (sample derived from [11]) revealed no sig-
nicant dierences (t=–1.46, p=0.05, z=1.96).
Discussion
e CBA with respect to in-brace correction seems supe-
rior to the FEMA (Figs. 5, 6). As in-brace correction and
compliance determine the outcome of brace treatment [3],
the CBA seems promising. e CBA was derived from the
latest renment of the Cheneau bracing, which reportedly
has the best in-brace correction exceeding 50% of the ini-
tial value of 66% [2].
The differences of in-brace corrections between CBA
and FEMA did not reach the level of signicance. Howev-
er, this may have reected the limited number of patients.
e two samples were comparable in Cobb angle (31° in
both).
CBA is readily available and can be used by submitting
the patients’ data, anthropometric measurements and pic-
tures (including the X-ray); or by submitting a scan le of
the patient together with the patients’ data and pictures
(including the X-ray). No stereo X-rays are necessary
for CBA. Like FEMA, CBA can be improved by time to
achieve a better in-brace correction.
Brace treatment can eectively halt progression. A re-
cent randomized controlled trial [13] demontrated that
72% of the United States and Canadian population com-
pliant with SRS inclusion criteria on bracing [14] did not
progress using the standard thoracolumbosacral orthosis
(TLSO, mainly Boston type). As FEMA does not seem
to provide better in-brace corrections than the standard
TLSO bracing in the United States [11], we would not be
able to predict an improved outcome when comparing
FEMA to the standard TLSO brace.
Fig. 4. Different models from the Gensingen brace computer aided design/computer aided manufacturing (CAD/CAM) library.
Development of CAD/CAM based brace models
Asian Spine JournalAsian Spine Journal
665
Fig. 6. Clinical result of a 15-year-old patient with a 42-degree Cobb angle at the start of treatment with marked progres-
sion within a few weeks. Right: clinical result following 6 months of treatment after outgrowing her rst brace. Pelvic
width has increased as compared to the photo at far left revealing skeletal immaturity at the start, age 15, although nor-
mally 15-year-old girls are nearly fully grown (to 99%). Reprinted from Weiss et al. [2], according to the Creative Commons
License of OA Publishing London.
Fig. 5. Brace from a patient with a full correction of the single thoracic curve pattern. This patient, from New Zealand, was
12 years old with Tanner II–III and so was still rather exible. Reprinted from Weiss et al. [2], according to the Creative Com-
mons License of OA Publishing London.
Hans-Rudolf Weiss et al.666 Asian Spine J 2015;9(5):661-667
A retrospective series using CBA in a sample fulfill-
ing the SRS inclusion criteria of the studies on bracing
revealed a success rate exceeding 95% [14,15]. This was
confirmed in another study using the correction princi-
ples according to Cheneau [16]. Recently, it was reported
that 33% of a population demonstrating improvements
of Cobb angle exceeding 5 degrees aer weaning o the
CBA braces, with none of the subjects requiring surgery
[17].
Considering that in-brace correction (and compliance)
determine the end result of bracing in the treatment of
scoliosis [3], we acknowledge that CBA is superior to
FEMA and to the standard brace applications used in
the United States and Canada [13]. For the best possible
results in terms of avoiding surgery at this stage, CBA
should be preferred [15].
FEMA is closely attached to the exterior surface of the
patient. How often such a brace has to be renewed dur-
ing growth is relevant an unanswered question. is also
applies to braces manufactured using 3D printing [18].
Even a marginal gains in pelvic size will make a new brace
necessary, because the FEMA and the actual 3D printed
models fully wrap the body in the brace, leaving no room
for growth (Fig. 7A).
The actual models of the CBA [12]–the Gensingen
brace series–have the advantage of covering only one pel-
vic half, which preserves room for the corrective move-
ment and an overlap of the ventral closure. erefore, we
can predict longer usage of the latter brace before out-
growth (Figs. 4, 7).
Conclusions
Considering that in-brace correction (and compliance)
determine the end result of bracing in the treatment of
scoliosis [3], currently the CBA approach of bracing sco-
liosis is superior to FEMA and the standard brace applica-
tions as used in the United States and Canada.
e actual models of the CBA–the Gensingen brace se-
ries–have the advantage of covering one pelvic half, which
preserves room for the corrective movement and overlap
of the ventral closure. erefore, longer usage of the latter
brace before outgrowth is likely.
Conict of Interest
Hans-Rudolf Weiss is receiving financial support for
attending symposia and receives royalties from Koob
Fig. 7. (A) Finite element modelling approach brace with little asymmetry (reprinted from Clin et al. [11]). (B, C) The classica-
tion based approach braces according to the Gensingen brace computer aided design/computer aided manufacturing (CAD/CAM)
library with clear asymmetry and good in-brace correction.
A B C
Development of CAD/CAM based brace models
Asian Spine JournalAsian Spine Journal
667
GmbH & Co KG.
Acknowledgments
All authors contributed to conception and design, manu-
script preparation, read and approved the final manu-
script. e authors are thankful to Dr. SY Ng, Hong Kong
for his helpful advice and for helping with copyediting of
this paper.
References
1. Weiss HR, Moramarco M. Scoliosis-treatment indi-
cations according to current evidence. OA Musculo-
skelet Med 2013;1:1.
2. Weiss HR, Seibel S, Moramarco M, Kleban A. Bracing
scoliosis: the evolution to CAD/CAM for improved
in-brace corrections. Hard Tissue 2013;2:43.
3. Landauer F, Wimmer C, Behensky H. Estimating the
nal outcome of brace treatment for idiopathic tho-
racic scoliosis at 6-month follow-up. Pediatr Rehabil
2003;6:201-7.
4. Clin J, Aubin CE, Labelle H. Virtual prototyping of a
brace design for the correction of scoliotic deformi-
ties. Med Biol Eng Comput 2007;45:467-73.
5. Labelle H, Belleeur C, Joncas J, Aubin CE, Cheriet
F. Preliminary evaluation of a computer-assisted tool
for the design and adjustment of braces in idiopathic
scoliosis: a prospective and randomized study. Spine
(Phila Pa 1976) 2007;32:835-43.
6. Clin J, Aubin CE, Parent S, Sangole A, Labelle H.
Comparison of the biomechanical 3D efficiency of
dierent brace designs for the treatment of scoliosis
using a finite element model. Eur Spine J 2010;19:
1169-78.
7. Clin J, Aubin CE, Parent S, Labelle H. Biomechanical
modeling of brace treatment of scoliosis: effects of
gravitational loads. Med Biol Eng Comput 2011;49:
743-53.
8. Clin J, Aubin CE, Sangole A, Labelle H, Parent S.
Correlation between immediate in-brace correction
and biomechanical eectiveness of brace treatment in
adolescent idiopathic scoliosis. Spine (Phila Pa 1976)
2010;35:1706-13.
9. Desbiens-Blais F, Clin J, Parent S, Labelle H, Aubin
CE. New brace design combining CAD/CAM and
biomechanical simulation for the treatment of ado-
lescent idiopathic scoliosis. Clin Biomech (Bristol,
Avon) 2012;27:999-1005.
10. Weiss HR, Rigo M, Cheneau J. Praxis der Cheneau-
Korsettversorgung in der skoliosetherapie.1st ed.
Stuttgart: ieme; 2000.
11. Clin J, Cobetto N, Desbiens-Blais F, et al. Advanced
brace design combining CAD/CAM and biomechan-
ical simulation for the treatment of adolescent idio-
pathic scoliosis. Proceeding of the OTWorld 2014;
2014 May 13; Leipzig, Germany.
12. Weiss HR. Standardising the treatment with Cheneau
braces via CAD: pospects and risks. OA Musculosk-
elet Med 2014;2:10.
13. Weinstein SL, Dolan LA, Wright JG, Dobbs MB. Ef-
fects of bracing in adolescents with idiopathic scolio-
sis. N Engl J Med 2013;369:1512-21.
14. Richards BS, Bernstein RM, D'Amato CR, Thomp-
son GH. Standardization of criteria for adolescent
idiopathic scoliosis brace studies: SRS Committee on
Bracing and Nonoperative Management. Spine (Phila
Pa 1976) 2005;30:2068-75.
15. Weiss HR, Werkmann M. Rate of surgery in a sample
of patients fullling the SRS inclusion criteria treated
with a Cheneau brace of actual standard. Stud Health
Technol Inform 2012;176:407-10.
16. De Giorgi S, Piazzolla A, Tafuri S, Borracci C, Mar-
tucci A, De Giorgi G. Cheneau brace for adolescent
idiopathic scoliosis: long-term results. Can it prevent
surgery? Eur Spine J 2013;22 Suppl 6:S815-22.
17. Weiss HR, Seibel S, Kleban A. Deformity-related
stress in a sample of patients with adolescent idio-
pathic scoliosis aer brace weaning: a cross-sectional
investigation. OA Musculoskelet Med 2014;2:5.
18. Chavez E. A perfect t: 3D systems unveils Bespoke 3D
printed braces for chronic scoliosis [Internet]. New
York: 3D Printing Industry; 2014 Jun 12 [cited 2015
May 29]. Available from: http://3dprintingindustry.
com/2014/06/12/perfect-fit-3d-systems-unveils-
bespoke-3d-printed-braces-chronic-scoliosis/.
... In traditional brace fabrication method a mold is taken from the patient spine, filled with plaster (to create positive cast) and finally modified based on the side of curvature, severity of the deformity and amount of correction required. The new approach of brace manufacturing is mostly based on computer aided design and manufacturing system (CAD/CAM) [38]. This system has being used in orthotics and prosthetics field since 1970's and was present officially in 1979 [46]. ...
... This new system was introduced in international society for prosthetics and orthotics world congress in 1983 in London. The system consists of three main parts, a digitizer unit, which converts 3D information of the body in digital format, a computer which is used to process the images, to convert them and to store them and a milling system to produce a cast from a 3d foam based on the rectified files [38]. ...
... The new braces were lighter with less body surface coverage. In another study done by Weiss and Kleban, on 21 scoliotic subjects it was shown that in-brace correction in CBA was 66 % of the initial value and for FEA was 42 % [38]. The results of this study confirmed that there was no difference between the corrections obtained, however it seems that CBA approach of bracing scoliosis is superior to FEA. ...
Evaluation of the effectiveness of scoliosis braces designed based on CAD CAM and manual casting. A review of literature
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Various methods of conservative treatment have been used to control the progression of scoliosis, including physical therapy and brace. Actually, there are two main approaches for fabrication of scoliotic braces. However, the main question posted here is that whether the braces produced based on CAD/CAM approach is more effective (To reduce the scoliosis curve based on Cobb angle) than the braces fabricated by manual casting or not. Therefore, the aim of this review was to compare the effectiveness of braces produced by CAD/CAM and manual method based on the available literature. Moreover, it was aimed to compare the quality of life of scoliotic subjects treated by the braces produced based on two mentioned approaches. A search was done in some data bases such as Google Scholar, PubMed, ISI Web of Knowledge, Ebsco and Scopus. CAD/CAM key word was used in combination with scoliosis. The quality of the studies was deter-mined by use of Black and Down tool. Actually 9 papers were found on combination of CAD/CAM and scoliosis in which, 5 papers were on comparison of the efficiency of the brace designed based on manual method and CAD/CAM. The other papers were on evaluation of the efficiency of the braces designed based on CAD/CAM with and without finite element analysis. The quality of the papers varied between 9 and 16. It can be concluded from the available studies that the braces designed based on CAD/CAM approach are lighter and more comfortable than the braces de-signed based on traditional method. However, there seems to be no difference between the effectiveness of the braces fabricated by CAD/CAM and manual casting.
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... Finite element modeling (FEM) provides a tool for detailed stress analysis, although few studies have rigorously validated their simulations with empirical data [5][6][7]. Grycuk and Mrozek recently presented an FEM model of the Boston brace that was experimentally verified using electronic speckle pattern interferometry (ESPI) [3]. The ESPI system evaluated surface displacements of the brace under a three-point loading scheme that mimicked corrective forces. ...
... study assumes point loads, it is recognized that in real-world applications, these forces would be distributed across the surface of the corrective pads, all while maintaining pressure within safe limits. It is worth noting that modeling brace pressure on the torso is a complex subject that has been the focus of extensive previous research [1,5,6]. However, the primary goal of this research is to optimize the structural and utility aspects of the brace shell, rather than to simulate the pressure exerted by the brace on the torso. ...
... Although the model used in this study assumes point loads, it is recognized that in real-world applications, these forces would be distributed across the surface of the corrective pads, all while maintaining pressure within safe limits. It is worth noting that modeling brace pressure on the torso is a complex subject that has been the focus of extensive previous research [1,5,6]. However, the primary goal of this research is to optimize the structural and utility aspects of the brace shell, rather than to simulate the pressure exerted by the brace on the torso. ...
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Orthoses are of critical importance in the field of medical biomechanics, particularly in the correction of spinal deformities. The objective of the current research was to improve the utility characteristics of the scoliosis brace without compromising its corrective capabilities. The orthotic shell of the Boston brace was used as the basis for this investigation. The finite element method (FEM) was used to evaluate the distribution of corrective forces through the device. The flow of force lines within the orthotic shell was determined by mapping the paths of maximum principal stresses. Areas of the device that had a negligible effect on overall stiffness were identified and material from these areas was eliminated. Minor modifications were then made to the redesigned shell to maintain its corrective stiffness. As a result of these changes, the weight of the braces was reduced without compromising its corrective stiffness. When subjected to corrective forces, the shell’s displacement patterns in the transverse plane showed minimal changes from the original model, confirming that its corrective capacity remained largely intact. This research presents an innovative methodology for orthotic design and demonstrates that structural optimization based on the mapping of maximum principal stress pathways can significantly improve device functionality. The approach outlined here holds promise for future advances in the design of various orthotic devices, thereby contributing to the advancement of the field.
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... Similar automated classification systems can significantly reduce doctors' workload and effectively prevent misdiagnosis, this also represents the future direction of automation in healthcare. Weiss et al. conducted a study on bracing using the classification-based approach for ALS and found the treatment outcomes were superior to those of the bracing based on the finite element modeling approach [128]. Unlike surgical Classification, LS and ALS curvature pattern scan be identified through the appearance of the back. ...
2D and 3D Classification Systems for Adolescent Idiopathic Scoliosis: Clinical Implications and Technological Advances
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Classification systems for Adolescent Idiopathic Scoliosis (AIS) play an important role in guiding both surgical planning and conservative treatments. Traditional 2D classification systems, such as the Lenke, King and Lehnert‐Schroth classifications, have been widely used for the clinical diagnosis and treatment of scoliosis. However, with the growing understanding of the three‐dimensional nature of scoliosis and advancements in 3D reconstruction technologies, 3D classification systems are gaining increasing attention. This paper reviews the current applications, advantages, and limitations of different 2D and 3D classification systems, focusing on their clinical significance in treatment planning. While 3D classification systems offer clear advantages in capturing the complexity of spinal deformities, their clinical implementation faces challenges such as high costs and technical complexity. Additionally, studies show that computer‐assisted technologies, artificial intelligence can significantly improve the accuracy and consistency of classification systems, reducing human errors. The paper also explores the future directions of classification system development, emphasizing the potential of combining 2D and 3D technologies and the impact of these advancements on personalized scoliosis treatment.
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... It should be declared that during this study, the authors did not have any intervention or authority to prescribe and suggest the type of brace treatment, and only participants from the three orthotic and prosthetic centers were invited. According to recent studies and the effectiveness of asymmetric design braces [42,43], it is suggested that in the future, a study with a qualitative approach should be conducted on the experience of wearing asymmetric design braces of adolescents with spinal deformities. ...
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Article
Full-text available
Background Adolescent idiopathic scoliosis affects 2–4% of adolescents aged 10–16, while Scheuermann’s kyphosis affects 0.4–10% of adolescents aged 11 to 16. Over the past 50 years, brace treatment has been recommended as the most common non-surgical intervention for treating these spinal deformities. The effectiveness of brace treatment depends on the duration of brace wearing. This study aimed to understand the brace compliance process for adolescents with spinal deformities through a qualitative approach. Method This study applied multicenter exploratory qualitative research with an interpretative framework and enlisted the participation of as many individuals as possible involved in brace-wearing in adolescents with spinal deformities. Semi-structured, in-depth, and face-to-face interviews and telephone conversations from September 2020 to May 2021 were conducted. The recorded audio of each interview was typed into Word software with each personal code. The content analysis method was used to analyze the data. Results Seventy-four participants were interviewed, including 32 adolescents treated with braces and their parents (27 mothers, five fathers), six orthotists, two physiotherapists, and two spine surgeons. Following data analysis, four main categories, 14 categories, and 69 subcategories of 2403 related codes were discovered. Conclusion Based on the analysis of the current qualitative research, adolescents with spinal deformities experience extensive challenges in the treatment process, which can affect the results and brace intervention efficacy. The current research findings showed that every adolescent goes through similar but unique conditions during the treatment. The importance of considering each adolescent’s specific conditions and characteristics and providing functional solutions and support was understood to help them navigate critical situations more quickly and achieve effective treatment outcomes.
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... CAD/CAMdesigned individual braces have corrected curvature angles by more than 30% from their initial measurements. Despite this, prolonged use of the Boston brace can cause distressing experiences for adolescents, such as the development of pressure-related scars, discomfort, emotional and social challenges, and disruptions in self-perception of body image (10). Furthermore, it has the potential to compress the thorax to a level that leads to a type of restricted ventilation dysfunction, thereby increasing the level of difficulty in breathing, termed dyspnea. ...
Impact of Computer-Aided Design and Computer-Aided Manufacturing Boston Brace on Level of Dyspnea among Patients with Adolescent Idiopathic Scoliosis
Article
Full-text available
  • Jun 2024
Background: Adolescent Idiopathic Scoliosis (AIS) is a prevalent spinal deformity characterized by a lateral curvature exceeding 10°. Bracing, particularly with the Boston brace, is a common conservative treatment aimed at halting the progression of spinal curvature. However, the impact of bracing on pulmonary function and the resultant dyspnea remains a concern, especially in developing countries like Pakistan where larger scoliotic curves are more common. Objective: This study aimed to evaluate the effect of the CAD/CAM Boston brace on dyspnea levels in patients with AIS and to examine the correlation between dyspnea severity, Cobb's angle, and the duration of brace wear. Methods: Necessary approvals were obtained from the institutional ethical review board, and informed consent was secured from all participants. The study included 145 participants (aged 10-19 years) diagnosed with AIS, recruited through non-probability convenient sampling. The sample size was calculated using the WHO sample size calculator, ensuring a minimum of 134 participants. Data collection involved the 6 Minute Walk Test (6MWT) followed by the Modified Borg Scale (MBS) to assess dyspnea. Participants were instructed to walk a distance of 400 to 700 meters within 6 minutes. Post-test, participants rated their dyspnea on a scale of 0 to 10. Demographic data and brace wear duration were also collected. Data were analyzed using SPSS version 25. Means and standard deviations were calculated for continuous variables, and frequency tables were used for categorical variables. Pearson correlation coefficients were computed to determine the relationships between dyspnea levels, Cobb's angle, and brace wear duration. Results: The mean age of participants was 14.71 years (SD = 2.309). The mean Cobb's angle was 52.08° (SD = 5.3729), and the mean duration of brace wear was 26.08 hours per week (SD = 7.0458). Dyspnea severity varied, with 54.5% of participants reporting "somewhat severe" dyspnea, 15.9% reporting "very, very severe" dyspnea, and 9.0% reporting "moderate" dyspnea. Pearson correlation analysis revealed a strong positive correlation between dyspnea severity and Cobb's angle (r = 0.681), and a moderate positive correlation between dyspnea severity and brace wear duration (r = 0.414). Conclusion: The study highlights the significant impact of the CAD/CAM Boston brace on dyspnea levels among AIS patients. Higher Cobb's angles and longer brace wear durations were associated with increased dyspnea severity. These findings underscore the need for careful monitoring of respiratory symptoms in AIS patients undergoing bracing and suggest exploring alternative or adjunctive treatments to minimize pulmonary compromise.
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... Future directions in the employment of braces for scoliosis treatment are poised to be influenced by advancements in orthotic design, technology, and patient-centered approaches. The development of CAD/CAM-based brace models has shown promise in providing a classification-based approach to bracing scoliosis, offering superior in-brace correction and compliance compared to standard brace applications [88]. Additionally, the integration of 3D printing technology in the workflow of scoliosis brace adjustment presents significant potential for personalized and user-friendly brace design, enhancing the overall effectiveness of bracing treatment [89]. ...
Spinal Orthosis in Adolescent Idiopathic Scoliosis: An Overview of the Braces Provided by the National Health Service in Italy
Article
Full-text available
Adolescent idiopathic scoliosis (AIS) is a lateral, rotated curvature of the spine. It is a 3-dimensional deformity that arises in otherwise healthy children at or around puberty. AIS is the most common form of scoliosis in the pediatric population. The etiology is multifactorial, including genetic and environmental factors. The incidence is roughly equal between males and females, while there is a higher risk of progression in females. Guidelines for AIS treatment identify three levels of treatment: observation, physiotherapy scoliosis-specific exercises, and braces. In this paper, we carried out a review of the scientific literature about the indication and success rates of the braces provided for free by the National Health Service in Italy (SSN). Despite a general consensus on the efficacy of rigid bracing treatment and its use in AIS, an important heterogeneity about the treatment is present in the scientific literature, demonstrating a high degree of variability. The overall success rate of the braces provided by the SSN is high, suggesting an important therapeutic role in the treatment of AIS. Robust guidelines are needed to ensure uniform and effective treatments.
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... Nonsurgical options for treating AIS include observation for minor curves less than 20°, bracing for moderate curves between 25 and 50° in skeletally immature patients or a scoliosis-specific exercise program [3]. The efficacy of braces has been established in the literature and early intervention of moderate curves in compliant patients plays a role in treatment success [4][5][6][7][8][9]. Improved bracing techniques are reportedly limiting curve progression and decreasing the necessity of surgical intervention [7]. ...
Epidemiologic patterns of adolescent idiopathic scoliosis detection and treatment in new york state
Article
  • Feb 2023
The purpose of this study is to examine the epidemiologic trends of adolescent idiopathic scoliosis (AIS) detection and treatment in New York State (NYS), including disparities in access. The New York Statewide Planning and Research Cooperative System database was reviewed to identify patients who underwent treatment for, or were diagnosed with, AIS from 2008 to 2016. Age determined adolescence; and the surgery date, 3-digit zip code, sex, race, insurance status, institution and surgeon license number were recorded to identify such trends. The geographical distribution was assembled from an NYS shapefile, obtained from the Topologically Integrated Geographic Encoding and Referencing database with analysis performed using tigris R. In total 54 002 patients with AIS, 3967 of whom were surgically treated, were identified for analysis. Diagnoses spiked in 2010. Females were diagnosed and underwent surgical treatment more frequently than males. AIS was diagnosed and treated in white patients more frequently than in black and Asian patients combined. From 2010 to 2013, the patients self-paying for surgical treatment decreased more than other payment modalities. Medium-volume surgeons continually increased the number of cases performed, whereas low-volume surgeons exhibited the opposite pattern. High-volume hospitals had a decrease in the number of cases from 2012 and were overtaken by medium-volume hospitals in 2015. Most procedures are performed within the New York City (NYC) area, though AIS was common in all NYS counties. AIS diagnoses increased after 2010, with fewer patients self-paying for surgery. White patients underwent more procedures than minority patients. Surgical cases were disproportionally performed in the NYC area compared to statewide.
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... In addition to the casting method, the development of computer-aided design and manufacturing (CAD-CAM) and CAD and finite element modeling (CAD-FEM) has increased the number of options for brace manufacture (Bidari et al., 2021). According to previous studies, the Cobb angle is better corrected by CAD-FEM and CAD-CAM methods compared with conventional methods (Weiss and Kleban, 2015). Although the braces designed using CAD-FEM have been put into clinical use, long-term effects have not been comprehensively evaluated. ...
Material sensitivity of patient-specific finite element models in the brace treatment of scoliosis
Article
Full-text available
  • Feb 2023
Objectives: To study the mechanical sensitivity of different intervertebral disc and bone material parameters and ligaments under different force configurations and magnitudes in the scoliosis model. Methods: The finite element model of a 21-year-old female is built using computed tomography. Local range of motion testing and global bending simulations are performed for the model verification. Subsequently, Five force of different directions and configurations were applied to the finite element model applying the brace pad position. The material parameters of the model were related to different spinal flexibilities and included different material parameters of cortical bone, cancellous bone, nucleus and annulus. The virtual X-ray technique measured Cobb angle, thoracic Lordosis, and lumbar Kyphosis. Results: The difference in peak displacement is 9.28 mm, 19.99 mm, 27.06 mm, 43.99 mm, and 50.1 mm under five force configurations. The maximum Cobb angle difference due to material parameters are 4.7° and 6.2°, which are converted to thoracic and lumbar in-brace correction difference of 18% and 15.5%. The maximum difference in Kyphosis and Lordosis angle is 4.4° and 5.8°. The average thoracic and lumbar Cobb angle variation difference in intervertebral disc control group is larger than that in bone control group, while the average Kyphosis and Lordosis angle is inverse. The displacement distribution of models with or without ligaments is similar, with a peak displacement difference of 1.3 mm in C5. The peak stress occurred at the junction of the cortical bone and ribs. Conclusion: Spinal flexibility largely influences the treatment effect of the brace. The intervertebral disc has a greater effect on the Cobb angle, the bone has a greater effect on the Kyphosis and Lordosis angles, and the rotation is affected by both. Patient-specific material is the key to increasing accuracy in the personalized finite element model. This study provides a scientific basis for using controllable brace treatment for scoliosis.
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Evaluation of In-Brace Coronal and Sagittal Plane Measurements Between CAD/Chêneau-Style and Traditionally Fabricated Wilmington Braces in Adolescent Idiopathic Scoliosis
Article
  • May 2024
Introduction Traditional thoracolumbosacral orthosis fabrication involves truncal casting (traditionally fabricated [TF] Wilmington brace [WB]), whereas the newer Chêneau-style brace (computer-aided design [CAD]) involves three-dimensional truncal scanning technology. We sought to evaluate how these two brace styles affect the position of the spine in the coronal and sagittal plane. Materials and Methods Inclusion criteria included adolescent idiopathic scoliosis treated with WB or CAD Chêneau-style brace, major curve Cobb angle 20°–45°, age 10–15 years, Risser 0–3, and radiographs (prebrace and in-brace posteroanterior and lateral). Analysis included 28 CAD Chêneau-style braces and 56 WB patients. Results There was no difference between groups regarding age, sex, body mass index, major curve location, major curve degree, sagittal plane curvature, and pelvic parameters. In-brace analysis demonstrated decreased sagittal plane curvatures and increased T1 pelvic angle in both groups; both had significantly reduced major curve correction. Coronal plane major curve correction ratio of the two groups was similar ( P = 0.236). In the CAD Chêneau-style brace group, the thoracolumbar junction became more kyphotic ( P = 0.03). In the WB group, both coronal balance and thoracic trunk shift were leftward ( P = 0.001). Both groups had a significant increase in T1 pelvic angle, but this increase was higher in the CAD Chêneau-style brace group ( P = 0.045). Conclusions Both braces exert a flattening effect on the spine and positive global sagittal balance. Coronal plane major curve correction was similar for both groups. Coronal plane trunk shift and C7 coronal balance were significantly changed leftward after WB application. Kyphotic thoracolumbar transition and forward tilt of the spine (T1 pelvic angle) were significantly greater in CAD Chêneau-style brace than WB. Clinical Relevance A Chêneau-style brace fabricated with CAD/computer-aided manufacturing technology can produce a brace comparable to one fabricated by traditional methods using cast molding.
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Numerical modelling of an orthopedic brace with increased functional characteristics for the treatment of idiopathic scoliosis
Article
  • Oct 2023
  • Tech Health Care
BACKGROUND: Orthotic braces play a key role in the correction of spinal deformities. The effectiveness of these devices depends on the design and distribution of corrective forces transmitted through the corset shell. OBJECTIVE: The present study aimed to reduce the weight of the orthosis and improve its functionality while maintaining its corrective function. METHODS: The distribution of corrective forces transmitted by the orthosis was evaluated using the finite element method (FEM). Areas of the orthosis, which had minimal impact on the overall stiffness, were identified and material from these areas was removed. The modified orthosis shell was subjected to minor adjustments to maintain its corrective stiffness. RESULTS: With the modifications made, a 39% reduction in the weight of the orthosis was achieved, while maintaining its corrective stiffness. This indicates that the corrective function was largely preserved. CONCLUSION: The study provides a novel approach to orthosis design demonstrating that optimizing the structure using the distribution of maximum principal stress trajectories can significantly improve the functionality of the brace. The proposed method offers potential advances in the design of various types of orthoses, contributing to developments in the field.
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Bracing scoliosis: The evolution to CAD/CAM for improved in-brace corrections
Article
Full-text available
  • Nov 2013
Introduction There are a wide variety of brace applications available today with different outcomes and different characteristics. The purpose of this study is to compare in-brace corrections of the series applied today to recent Chêneau series braces as presented in literature. Methodology All patients were registered and fulfil the Scoliosis Research Society inclusion criteria for studies on bracing from 2012. A total of 21 female patients matched with the Scoliosis Research Society inclusion criteria. These 21 girls were of an average age of 12.2 years (standard deviation = 1.1). Average Risser stage was 0.38 (standard deviation = 0.68), average Cobb angle was 31.33° (standard deviation = 6.58). In-brace correction from this sample has been compared to the in-brace corrections of other Chêneau samples as published in literature using a test for comparison of two different proportions. Average Cobb angle in the brace was 10.66°; 34% of the initial angle that makes an in-brace correction of 66%. A significant difference is revealed for some samples and the absolute in-brace correction was highest in our sample showing that the application of the actual state of computer-aided design/computer-aided manufacturing braces leads to better in-brace corrections than many cast-made braces, and also better in-brace corrections when comparing to computer-aided design/computer-aided manufacturing braces as published. Conclusion Symmetric braces are outdated. Asymmetric braces allow better in-brace correction when compared to symmetric braces. Asymmetric braces according to the actual, Best Practice® computer-aided design/computer-aided manufacturing standard allow for improved in-brace corrections promising the best possible radiological and cosmetic end results. Future studies on in-brace corrections and outcomes on brace treatment should use the Scoliosis Research Society inclusion criteria for bracing to improve comparability.
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Effects of Bracing in Adolescents with Idiopathic Scoliosis Reply
Article
Full-text available
  • Sep 2013
  • NEW ENGL J MED
Background The role of bracing in patients with adolescent idiopathic scoliosis who are at risk for curve progression and eventual surgery is controversial. Methods We conducted a multicenter study that included patients with typical indications for bracing due to their age, skeletal immaturity, and degree of scoliosis. Both a randomized cohort and a preference cohort were enrolled. Of 242 patients included in the analysis, 116 were randomly assigned to bracing or observation, and 126 chose between bracing and observation. Patients in the bracing group were instructed to wear the brace at least 18 hours per day. The primary outcomes were curve progression to 50 degrees or more (treatment failure) and skeletal maturity without this degree of curve progression (treatment success). ResultsThe trial was stopped early owing to the efficacy of bracing. In an analysis that included both the randomized and preference cohorts, the rate of treatment success was 72% after bracing, as compared with 48% after observation (propensity-score-adjusted odds ratio for treatment success, 1.93; 95% confidence interval [CI], 1.08 to 3.46). In the intention-to-treat analysis, the rate of treatment success was 75% among patients randomly assigned to bracing, as compared with 42% among those randomly assigned to observation (odds ratio, 4.11; 95% CI, 1.85 to 9.16). There was a significant positive association between hours of brace wear and rate of treatment success (P<0.001). Conclusions Bracing significantly decreased the progression of high-risk curves to the threshold for surgery in patients with adolescent idiopathic scoliosis. The benefit increased with longer hours of brace wear. (Funded by the National Institute of Arthritis and Musculoskeletal and Skin Diseases and others; BRAIST ClinicalTrials.gov number, NCT00448448.)
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Chêneau brace for adolescent idiopathic scoliosis: long-term results. Can it prevent surgery?
Article
Full-text available
  • Sep 2013
  • EUR SPINE J
The aim of this study was to evaluate the effectiveness of Chêneau brace in the management of idiopathic scoliosis. This is a retrospective observational study according to SOSORT and SRS (Scoliosis Research Society) recommendations involving 48 girls with documented progressive idiopathic scoliosis, treated with Chêneau brace. A statistical analysis was performed with STATA MP11.2 to validate the obtained results. No patient needed surgery. The average curve angle measured in Cobb degrees passed from 27° ± 6.7° at the beginning (T0), to 7.6° ± 7.4° in brace (T1) (72 % of correction), to 8.5° ± 8.6° (69 % of correction) at the end of treatment (T2), to 11.0° ± 7.4° (59.3 % of correction) at final follow-up (mean 5 years and 5 months) (T3). Conservative treatment with Chêneau brace and physiotherapy was effective in our hands for halting scoliosis progression in 100 % of patients.
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Weiss HR, Moramarco M. Scoliosis – treatment indications according to current evidence. OA Musculoskeletal Medicine 2013 Mar 01;1(1):1.
Article
  • Mar 2013
Weiss HR, Moramarco M. Scoliosis – treatment indications according to current evidence. OA Musculoskeletal Medicine 2013 Mar 01;1(1):1. Abstract Long-term follow-ups of untreated patients with Adolescent Idiopathic Scoliosis (AIS) indicate that the consequences of AIS over a lifetime are minimal, sometimes moderate in more severe cases, however, never life threatening. In light of these findings, the historical indications for treatment should be investigated according to current evidence. Recent reviews have been investigated for their contribution to evidence in the field of scoliosis treatment; especially the impact of the results obtained on the historical modes of treatment. From the findings, we may conclude that there is promising evidence for the application of physiotherapy in the treatment of scoliosis in children or adolescents and for adults with curvatures exceeding 35° Cobb. There is stronger evidence for the application of (hard) braces during growth. There is no evidence for spinal fusion surgery for AIS. The use of surgery should be limitedin patients with scoliosis of other origin.
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Rate of Surgey in a Sample of Patients fulfilling the SRS Inclusion Criteria treated with a Chêneau Brace of actual Standard
Article
  • Jun 2012
  • Stud Health Tech Informat
Studies investigating the outcome of conservative scoliosis treatment differ widely with respect to the inclusion criteria used. Prospective cohort studies are available using the SRS inclusion criteria for studies on bracing. This seems to provide a great advantage to compare different strategies of bracing against each other. As we have gathered all data of the patients treated with a Chêneau light TM between June 2005 and November 2007 it was possible to identify the sample of patients fulfilling the SRS inclusion criteria from the whole sample. 34 patients (of 152) fulfilled the SRS inclusion criteria with an average age of 12.06 years (10 - 13 years), average Cobb angle of 31 degrees (25 - 40°), an average Risser stage of 0,35, average in-brace Cobb angle of 13° (= 59% of in-brace correction). There were 17 thoracic, 10 double major, 6 lumbar and 2 thoracolumbar curve patterns. After change of workplace of the second author the patients could not be followed up as planned. Therefore a telephone interview was performed by the second author. Results: 28 patients (average age 16.5 years) have been reached, 9 of them were still under treatment. No patient has been operated (Rate of surgery 0%) and only one was not satisfied with cosmetic outcome of treatment. Rate of surgery was far less than reported in recent studies using the same inclusion criteria even when all drop outs where rated as failures. Rate of surgery can be reduced with the help of Chêneau braces of the latest standard and satisfactory in-brace correction. Brace treatment with the Chêneau brace seems effective and therefore clearly is indicated. Clinical outcomes may be more important for the patient than radiologic outcomes.
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Preliminary Evaluation of a Computer-Assisted Tool for the Design and Adjustment of Braces in Idiopathic Scoliosis
Article
  • Apr 2007
  • SPINE
Prospective and randomized clinical study. To evaluate the correction of the spine obtained using a 3-dimensional visualization software tool developed to assist the design and adjustment of braces compared with the correction obtained with the conventional method in a cohort of subjects with adolescent idiopathic scoliosis (AIS). The optimal design and adjustment of trim lines, pad placement, and areas of relief for the Boston brace system in AIS are currently done using clinical examination and coronal radiographs. Correction of spinal curves in the coronal plane has been achieved with this technique, but 3-dimensional correction has yet to be demonstrated. Forty-eight consecutive subjects with AIS requiring treatment with a Boston brace were prospectively entered in the study. For 24 patients (test group), brace design and adjustment was obtained using the computer-assisted tool combining surface topography, surface pressure measurement, and 3-dimensional reconstructions of the trunk, while design and adjustment for the remaining subjects (control group) was done in the conventional manner. Immediate in-brace correction of the spine at the initial visit was compared in both groups. Both groups were comparable in terms of age, sex, curve type, and average deformity in both the coronal and sagittal planes. The average prebrace thoracic deformity was 35 degrees of Cobb angle, while the average lumbar curve was 32 degrees in the test group and 35 degrees in controls. A statistically and clinically significant improvement in correction of coronal curves and of curves in the plane of maximal deformity was found for both thoracic and lumbar curves in both groups, but the improvement was significantly greater in the test group. The average in-brace correction in the test group was 12 degrees +/- 7 degrees compared with 7 degrees +/- 5 degrees in the control group for thoracic curves, while the average in-brace correction in the test group was 10 degrees +/- 5 degrees compared with 6 degrees +/- 5 degrees in the control group for lumbar curves. Similar average corrections were detected in the plane of maximal deformity. In addition, a significant improvement in the orientation of the plane of maximum deformity from 37 degrees to 23 degrees for lumbar curves was noted only in the test group, indicating that true 3-dimensional correction by the brace was obtained in this group. It is possible to improve the design and adjustment of braces in AIS and to achieve 3-dimensional correction of scoliotic curves with the use of a computer-assisted tool allowing 3-dimensional visualization of the spinal curves and the external shape of the trunk.
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Correlation Between Immediate In-Brace Correction and Biomechanical Effectiveness of Brace Treatment in Adolescent Idiopathic Scoliosis
Article
  • Aug 2010
  • SPINE
Multiple brace designs were simulated using a finite element model and their biomechanical effect was evaluated. To study correlations between immediate in-brace correction of coronal curves and bending moments acting on the apical vertebrae. Immediate in-brace correction has often been deemed as fundamental to long-term brace effect but the biomechanical explanation is unclear. Three-dimensional geometry of 3 patients was acquired using multiview radiographs and surface topography techniques. A finite element model of the patients' trunk including gravitational forces and a parametric brace model were created. Two sets of mechanical properties of the spine (stiff and flexible) were tested. Installation of the brace on the patients was simulated. Using an experimental design framework including fourteen design factors, 1024 different virtual braces were tested for each patient. For each brace, immediate in-brace correction of the coronal Cobb angles and the bending moment acting on the apical vertebrae were computed and their correlation was studied. Immediate correction of coronal curves and corresponding impact on the apical vertebrae bending moments were linearly correlated (mean R = 0.88). The amount of immediate correction necessary to nullify the bending moment ranged between 19% and 61% with average 48% (flexible spine model) and 27% (stiff spine model). The braces corrected the apical vertebrae bending moment more in the flexible spine model. In the framework of the Hueter-Volkmann principle, the correlation between coronal immediate in-brace correction and corresponding apical bending moment can be interpreted as a correlation between immediate in-brace correction and long-term treatment outcome. The amount of immediate correction necessary to invert the bending moments, and in theory counteract the progression of the scoliotic deformity, depends on spine stiffness and spine segment. This study confirms the importance of immediate in-brace correction to predict long-term outcome of the treatment and provides insights in the understanding of brace biomechanics.
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Biomechanical modeling of brace treatment of scoliosis: Effects of gravitational loads
Article
  • Feb 2011
  • MED BIOL ENG COMPUT
The biomechanics of bracing in adolescent idiopathic scoliosis is still not fully understood. Finite element models (FEM) have been used but the gravity forces were not included and the production of spinal stresses not evaluated. An improved FEM to simulate brace treatment was thus developed. The 3D geometry of the spine, rib cage, pelvis, and of the trunk external surface of five scoliotic patients was acquired using a multi-view X-ray technique and surface topography. A FEM of the patient's trunk including gravity forces was created. Custom-fit braces were modeled and their installation simulated. Immediate geometrical corrections and pressures were computed and validated. The resulting compressive loads on the vertebral endplates were quantified. The influence of the strap tension, spine stiffness, and of the gravity forces was evaluated. Results showed that the brace biomechanical action was importantly to prevent the scoliotic spine from bending under the gravity forces. The immediate correction depended on the strap tension and spine stiffness. The distribution and amplitude of computed pressures were similar to those measured with the real braces. After the brace installation, the coronal asymmetrical compressive loading on the vertebral endplates was significantly reduced. In conclusion, the model developed presents improvements over previous models and could be used to better understand and optimize brace treatment.
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Comparison of the biomechanical 3D efficiency of different brace designs for the treatment of scoliosis using a finite element model
Article
  • Jul 2010
  • EUR SPINE J
The biomechanical influence of thoraco-lumbo-sacral bracing, a commonly employed treatment in scoliosis, is still not fully understood. The aim of this study was to compare the immediate corrections generated by different virtual braces using a patient-specific finite element model (FEM) and to analyze the most influential design factors. The 3D geometry of three patients presenting different types of curves was acquired with a multi-view X-ray technique and surface topography. A personalized FEM of the patients' trunk and a parametric model of a virtual custom-fit brace were then created. The installation of the braces on the patients was simulated. The influence of 15 design factors on the 3D correction generated by the brace was evaluated following a design of experiments simulation protocol allowing computing the main and two-way interaction effects of the design factors. A total of 12,288 different braces were tested. Results showed a great variability of the braces effectiveness. Of the 15 design factors investigated, according to the 2 modalities chosen for each one, the 5 most influential design factors were the position of the brace opening (posterior vs. anterior), the strap tension, the trochanter extension side, the lordosis design and the rigid shell shape. The position of the brace opening modified the correction mechanism. The trochanter extension position influenced the efficiency of the thoracic and lumbar pads by modifying their lever arm. Increasing the strap tension improved corrections of coronal curves. The lordosis design had an influence in the sagittal plane but not in the coronal plane. This study could help to better understand the brace biomechanics and to rationalize and optimize their design.
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