For citation purposes: Weiss HR, Seibel S, Moramarco M, Kleban A. Bracing scoliosis: The evolution to CAD/CAM for improved in-brace corrections. Hard Tissue 2013 Nov 25;2(5):43.

Methodology

 
Spinal Surgery

Bracing scoliosis: the evolution to CAD/CAM for improved in-brace corrections

HR Weiss1*, S Seibel1, M Moramarco2, A Kleban3
 

Authors affiliations

(1) Orthopedic Rehabilitation Services ‘Gesundheitsforum Nahetal’, Gensingen, Germany

(2) Scoliosis 3DC, Baldwin Green Common, Woburn, Massachusetts USA

(3) Lomonosov Moscow State University. Faculty of Mechanics and Mathematics GSP-1, Leninskie Gory, Moscow, Russia

* Corresponding author Email: hr.weiss@skoliose-dr-weiss.com

Abstract

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Symmetric braces are outdated.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.

Introduction

Scoliosis is a three-dimensional deformity of the spine and trunk, which may deteriorate quickly during phases of rapid growth[1]. Although research is still being conducted on the effects of physiotherapy[2] for scoliosis, bracing is recognized to stop progression[3] during the pubertal growth spurt. Now, with the newest Chêneau style computer-aided design/computer-aided manufacturing (CAD/CAM) bracing under certain circumstances the potential exists to improve curvature radiologically and visually[4].

With the variety of brace applications available today, there are different characteristics with varying outcomes. Independent studies have shown that soft braces have no advantage over rigid braces[5,6,7,8].

Rigid braces may be symmetric or asymmetric. Examples of symmetric braces are the Boston brace[9] or the symmetric, patient-oriented rigid trunk orthosis (SPORT) brace from Italy[10]. No in-brace corrections are reported for the latter brace (Figure 1).

A 7-year-old girl from Italy treated with brace known as SPORT brace. The patient is squeezed as evidenced by the marked impressions on the skin. An example of this type of brace is shown on the right. This brace does not appear to be patient-oriented.

Symmetric braces have pad inlays that push on the most prominent areas of the scoliotic trunk. Asymmetric braces are constructed in an attempt for overcorrection with foam pads used for augmentation in the pressure areas but also for providing spaces on the opposing sides of the pressure areas. The most effective asymmetric brace is the Chêneau brace[11]. The primary advantage of the Chêneau brace over symmetric braces is the higher in-brace correction [11]. Its unique structure allows for a correction in three dimensions (in the sagittal, frontal and transverse planes) and allows room for corrective breathing; a concept in sync with principles of non-surgical scoliosis management via Best Practice® based upon Schroth Method principles. The newest Chêneau brace is also manufactured using less material making the brace lighter than previously manufactured braces with the goal of improving comfort and wearability offering increased likelihood of improved patient compliance (Figure 2).

Left: Chêneau (Gensingen) CAD/CAM brace clearly mirroring the deformity. The type of curve pattern as treated and the corrective movement is clearly visible in the brace (middle). Right: Rigo Chêneau brace made by cast in the US lacking visible correction of the right thoracic deformity and far more material than current Chêneau (Gensingen).

It is generally agreed that bracing outcomes are determined by the amount of in-brace correction and compliance[12]. Therefore, the aim of future developments should be improvement of in-brace correction and comfort. A recent study reveals that not all Chêneau braces are of comparable quality or have the ability to achieve the same in-brace correction. Borysov and Borysov have demonstrated the capability to attain a high standard with hand-made braces using the plaster technique[13], however, the outcomes of Chêneau braces created elsewhere have varied significantly; between 56%[14] and >95% successful[15] based on in-brace correction.

Chêneau braces made by the cast technique are at a disadvantage because they lack standardization. Even among specialists, there will always be a wide range of quality. When constructing a brace by cast, the clinician must start anew each time without a baseline standard. With each correction and alteration, the brace is vulnerable to deterioration. These deteriorations can cause the brace's function to veer from the original intended curve pattern correction (Figure 2).

A solution is CAD/CAM technology. For 3 years, brace formulas from a library created by the first author have been used to address specific curvature patterns[16]. The augmented Lehnert-Schroth (ALS) classification determines which brace formula from the library is best matched to an individual patient (Figure 3). These basic patterns are key patterns. Special patterns are also available for certain presentations, such as double thoracic patterns, kyphotic patterns and adults. Furthermore, each brace (whether made from key patterns or special patterns) from the library are always customized to the individual through adjustments for comfort and function.

ALS classification as used for the selection of the appropriate brace from our Gensingen library. (From left to right) 3CH, 3-curve with hip prominence; 3CTL, 3-curve with hip prominence thoracolumbar; 3C, 3-curve balanced; 3CL, 3-curve with long lumbar countercurve; 4C, 4-curve double; 4CL, 4-curve single lumbar; 4CTL, 4-curve single thoracolumbar.

The baseline standard of these braces can be improved without generating new problems by adjusting unforeseen complications. Any reported problems with the braces created from the library are registered and are easily modified using CAD. After CAD modification, the problem is solved for the entire series. When compared to previously worn braces, patients have reported braces from the library (Figure 3, Figure 4, Figure 5) to be more comfortable.

Brace from a patient of this series with a full correction of the single thoracic curve pattern. This patient, from New Zealand, was 12 years old with Tanner II–III and therefore still rather flexible.

Clinical result of a 15-year-old patient with a 42° Cobb angle at the start of treatment with marked progression within a few weeks. Right: Clinical result following 6 months of treatment after outgrowing her first brace. Pelvic width has increased as compared to the photo at far left revealing skeletal immaturity at the start, age 15, although normally 15-year-old girls are nearly fully grown (to 99%).

The purpose of this study is to compare in-brace correction of the CAD/CAM series as currently applied to the Chêneau series as presented in literature previously[13].

Methodology

The authors have referenced some of their own studies in this review. These referenced studies have been conducted in accordance with the Declaration of Helsinki (1964) and the protocols of these studies have been approved by the relevant ethics committees related to the institution in which they were performed. All human subjects, in these referenced studies, gave informed consent to participate in these studies.

In 2011, a prospective trial commenced using the referenced CAD/CAM approach. Patients included were from November 2011 to December 2012.

In accordance with Scoliosis Research Society (SRS) inclusion criteria for studies on bracing all patients fulfilled the following criteria[17].

The SRS inclusion criteria for bracing studies:

> Age at bracing = 10 years and older

> Primary curve = 25–40°

> Risser sign = 0, 1 or 2

> No prior treatment

> Females—premenarchal or one-year postmenarchal

> Include all patients regardless of compliance (‘intent to treat’)

The 21 females who matched the criteria were of an average age of 12.2 years [standard deviation (SD) = 1.1] with the following distribution of curve patterns:

> Thoracic: n = 11

> Double major: n = 4

> Lumbar: n = 4

> Thoracolumbar: n = 2

Average Risser stage was 0.38 (SD = 0.68) and average Cobb angle was 31.33° (SD = 6.58).

In-brace correction from this sample has been compared to the in-brace correction of other Chêneau samples as published in literature[11,13,15,18,21].

Results

Average Cobb angle in brace for our sample was 10.66° (SD); 34 % of the initial angle resulting in an in-brace correction of 66%.

The results in comparison to others are demonstrated in Table 1. A significant difference is revealed showing that the application of CAD/CAM braces leads to better in-brace corrections than cast-made braces, and also better in-brace corrections than previous results for CAD/CAM braces as previously published (RSC)[19].

Table 1

Papers on the Chêneau brace treatment of patients with Adolescent Idiopathic Scoliosis as can be found in PubMed and the journal ‘Scoliosis’ where the average in-brace correction (ϕ corr) is documented (ϕ corr and ϕ Cobb angle have been rounded). Statistical analysis revealed significant differences of the in-brace correction achieved when the results from this sample (Weiss et al., 2013) were compared to previous studies[11,18,21] (t = 2.4 and 3.64, respectively, in a statistical test to compare two different proportions)

Discussion

During growth, it is of vast importance that brace treatment is established immediately and with the most effective brace available. To attempt an early reduction of the curvature, the earliest onset of treatment with the highest in-brace correction is desirable. When the first signs of maturation appear, immediate treatment offers the benefit of the shortest possible length of treatment, allowing for the least impact on the patients’ quality of life and perhaps improving the likelihood of improved patient compliance. With increasing age and curvatures, the possibility for a curve correction via bracing is reduced. Due to growth dynamics, in females, the best chance for correction is before the onset of menarche, and for males before voice change. In limited cases, drastic improvements have been achieved when a growth peak occurs in immature patients (Figures 46).

Rib hump of the patient from Figure 5 left at the start and right after 6 months of brace treatment.

Missing the opportunity for treatment at the optimal time may result in an increased risk for curve progression. If curve progression occurs to the point when surgery is commonly recommended, usually 45°–50°, a patient's risk for long-term health complications as a result of scoliosis increases[22,24].

These newer developments in CAD/CAM-based standardization make it possible for improved patient outcomes, especially when the patient is treated early at an immature phase[4] (Figures 4 and 7). Curvatures exceeding 45° may now be addressed offering the patient the chance for improved trunk appearance and Cobb angles, but in-brace correction may be difficult to achieve (Figure 8). Early treatment (before 45° is reached), combined with this newest bracing standard may at times indicate a short-term wearing schedule: 23 h/day for possibly up to only 6 months[25]. If a curve has been corrected to less than 20° (out of the brace) as an intermediate result, then part-time brace wear will be sufficient.

Immature patient initially treated for a curve of more than 30° at the age of 8 (left). During the growth spurt, part-time treatment is enough as the curve is below 20° as illustrated in the intermediate result (far right). The 2nd, 4th and 6th x-rays from the left are in-brace x-rays showing that there was no further improvement possible with respect to in-brace correction[25].

A 14-year-old girl from the US with a 53° curve thoracic to the right. As she is still skeletally immature (Risser 2), the first author decided to brace her pattern specifically with a 3CL Chêneau brace from the Gensingen CAD/CAM library. In the end, the curve corrected minimally in the thoracic area (to 40°) and the apical area in the x-ray seems quite stiff. Nevertheless, a slight correction can be expected upon outgrowing the brace. The next brace will be of the 3CH model (see Figure 5) shifting the decompensated trunk even more to achieve an improved good cosmetic outcome.

Bracing standardization allows consistent and optimal treatment for patients. Nevertheless, there are curves that present challenges (Figures 9 and 10). Fortunately, this applies to a smaller percentage of the population (estimated at 5%). In these cases, correction is not a typical outcome, but the curves presented by this population can usually be kept stable with full compliance.

Patient with a double major curvature (high lumbar, low thoracic) treated with a Chêneau brace of the early CAD standard 10 years ago. Curvature correction was limited. A switch to the Chêneau light did not result in a better radiological correction either. However, the curve stayed stable even without a significant in-brace correction.

Clinical outcome of the patient from Figure 7. Even without any radiological correction, the trunk deformity in this patient has been improved significantly over the treatment period leading to patient satisfaction in the end.

In a recent retrospective cohort study on Chêneau braces[26] from Italy, the authors report high in-brace corrections and a success rate of more than 95% as published in 2012 in a series of the first author[15]. However, the average Cobb angle in the sample of patients from Italy as reported is rather low. In addition, only selected single patterns of curvature have been included. The average Cobb angle of the subset of patients with thoracic curvatures is only 24°, and thus is not comparable to the other samples in Table 1. Unlike in the other studies, double curvatures obviously have been excluded. Despite these limitations, the final results, as reported, must be regarded as far above average.

In-brace correction is more easily and more safely achieved with braces from the standardized CAD library developed by the first author. In comparison, cast braces do not offer the same basis of standardization that can allow the patient the potential for improved in-brace corrections and outcomes. Unfortunately, there are a few individuals skilled enough to reproduce the standard of CAD technology via casting[13].

Since November 2011 when the prospective study was started, we have applied more than 600 CAD/CAM Chêneau braces in Gensingen. Many of these patients before the study start have been treated elsewhere or in first author's clinic; many patients’ age exceeded the limits of the SRS inclusion criteria. Many patients had curvature angles exceeding 40°. Therefore, we were able to include only this small number (21 patients) into the current study.

This exactly is the problem that many patients come late to be braced, at an age and with a Cobb angle that no longer fit within the margins of the SRS inclusion criteria.

Many patients with scoliosis, therefore, are needed to start such an endeavour of a prospective cohort complying with these criteria.

Cobb angle, on the other hand, certainly cannot be regarded as the most important outcome measure for the patient. As has been demonstrated, our new series of CAD/CAM Chêneau braces is able to improve trunk asymmetry significantly even in curves exceeding 40° Cobb angle. Maybe in the future we will be able to change the measure for outcome from the Cobb angle to cosmetic issues, which might be more important for the patients themselves.

Symmetric braces will not allow the best possible in-brace correction and therefore are outdated today and should no longer be used as these do not promise the best possible percentage of beneficial outcomes and final corrections especially in curves exceeding 45° have never been demonstrated using symmetric braces[27].

Conclusion

> Symmetric braces are not of the same standard as asymmetric braces.

> Asymmetric braces allow better in-brace correction.

> Asymmetric braces according to the Best Practice® CAD/CAM standard allow for optimal in-brace correction that in turn yields the best possible end result.

Acknowledgement

All patients visible on the pictures and their parents have kindly agreed to the publication of their photos within this article. The authors are thankful to Kathy Moramarco for copyediting the manuscript and for her precious suggestions.

Abbreviations list

ALS, augmented Lehnert-Schroth; CAD, computer-aided design; CAM, computer-aided manufacturing; SD, standard deviation; SPORT, symmetric, patient-oriented rigid trunk orthosis; SRS, Scoliosis Research Society.

Authors Contribution

All authors contributed to the conception, design, and preparation of the manuscript, as well as read and approved the final manuscript.

Competing interests

HR Weiss is advisor of Koob GmbH & Co KG

Conflict of interests

HR Weiss is advisor of Koob GmbH & Co KG, M Moramarco is a US provider of the Chêneau Gensingen Brace™.

A.M.E

All authors abide by the Association for Medical Ethics (AME) ethical rules of disclosure.

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Licensee to OAPL (UK) 2013. Creative Commons Attribution License (CC-BY)

Papers on the Chêneau brace treatment of patients with Adolescent Idiopathic Scoliosis as can be found in PubMed and the journal ‘Scoliosis’ where the average in-brace correction (ϕ corr) is documented (ϕ corr and ϕ Cobb angle have been rounded). Statistical analysis revealed significant differences of the in-brace correction achieved when the results from this sample (Weiss et al., 2013) were compared to previous studies11,18,21 (t = 2.4 and 3.64, respectively, in a statistical test to compare two different proportions)

Authors Year n ϕ corr ϕ Cobb significance
Hopf and Heine11 1985 52 41% 36° 0.05
Rigo et al.18 2002 105 31% 37° 0.01
Rigo19 2007 32 42% 33° ns
Weiss et al.20 2007 81 51% 36° ns
Maruyama et al.21 2012 54 36% 37° 0.05
Weiss and Werkmann15 2012 34 59% 31° ns
Borysov et al.13 2013 92 56% 29° ns
Weiss et al. (this study) 2013 21 66% 31°