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

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Scoliosis > 40°

 


We will consider in this module, most of the innovations of the new Lyon ARTbrace. They are linked to the development of CAD / CAM systems, advances in plastics technology and a better understanding of 3D Correction.

The ARTbrace was originally created to replace the abbott plaster cast which was preceding systematically the fitting of the Stagnara brace. How to avoid the plaster cast?

Lyon has always had a great tradition of Orthopaedic and Charles Gabriel Pravaz was not only the inventor of the syringe, but he also created in Lyon a great Orthopaedic Institute to treat scoliosis 200 years ago. The first Lyon brace in leather and steel was created by Stagnara 70 years ago. It undergoes a first change with the replacement of leather by polymethacrylate. 3 years ago, the use of polycarbonate and asymmetry allowed to avoid the plaster cast which was the characteristic of the Lyon Brace.

The treatment of adolescent idiopathic scoliosis has traditionally been divided into two phases, correction and stabilization. The correction phase has been performed using casts. They were used systematically for all cases before the Lyon brace. The Lyon plaster cast was asymmetrical.

Why the plaster cast? A tensile stress is a stress that tends to stretch or lengthen the material. Strain is defined as deformation of a solid due to stress. Like the old plaster cast, with an initial full time at least 4 weeks, the structure does not return to its initial size and its original shape after removal of applied loads. It's a plastic permanent behavior or creep, after exceeding the elastic limit.

The preparation of casts is complex, time-consuming and costly (in-patient treatment or day hospital, hand-made by physicians); it has a high impact on the patient's quality of life. The possible side effects are important, from cast syndrome to skin problems.

Trying to avoid the plaster cast is not a new concept, but ART is the 1st Asymmetrical corrective brace (like cast).

The first tentative was the Sforzesco brace. Although the initial results were very encouraging for curves of more than 40°, the authors concluded: "The reduction of thoracic ATR and rib hump is higher in Risser cast than in Sforzesco brace. The fact that thoraco-lumbar curves, as well as ATR and rib hump, have been better corrected in Risser cast than in Sforzesco should be carefully considered in the future. The major problem is probably the lack of external asymmetry as in the plaster cast.

A plastic deformity of the concavity requires an overcorrection of the curvature during the full time. The only possibility of obtaining an overcorrection and asymmetry.

In this case the benefit of the asymmetry is evident.

The ARTbrace is currently the most corrective brace with an average in-brace correction of 70% due to this asymmetry and overcorrection.

The main innovative features are in the acronym of ART.

First. A stands for Asymmetry obtained with an overlay of three regional shapes captures.

Second. R stands for Rigidity (in fact High rigidity) of polycarbonate.

Third. T stands for Torsion: the brace performing a Detorsion of the scoliotic Torso Column which is a circled helicoid with horizontal generating circle in opposite direction of the spiral column while fixing the sagittal plane in a physiological position.

The asymmetry is obtained by the superposition of three regional shape captures in postures associating a frontal and sagittal reproducible correction. It is the child himself who ensures the highest possible correction. A specific CAD/CAM device with video control is necessary.

This asymmetry is obtained by a regional mould that includes 3 stages:

First. Auto-active axial elongation and sagittal positioning of the pelvis,

Second. Shift and lumbar lordosis,

Third. Bending and thoracic kyphosis,

The first shape capture is in axial self-active elongation with control of the pelvic tilt. A visual antero-posterior and latero-lateral control is essential. The pelvic tilt is corrected with data of the sagittal meter.

The basic use of sagittalometer is the calculation of the pelvic incidence. Pelvic incidence is a constitutional factor and does not vary during the movements in the sagittal plane. The eventual recovery of curvatures in the sagittal plane will be facilitated.

Shape capture number 2 made with lumbar frontal shift and lumbar physiological lordosis under visual control.

Shape capture number 3 is performed in thoracic kyphosis and frontal bending. It is impossible to make the thoracic bending without specific positioning of the upper limb of the concave side. Spontaneously, the child tilts his head to the convexity.

The second step is the superposition of the three shapes. It is this superposition that performs overall untwisting of the spine in the opposite direction of the scoliosis.

First. The sagittal plane is fixed. The posterior bar reproduces exactly the lordo-kyphosis we wish to give to the patient.

Second. The frontal plane reproduces the correction obtained by the shift. Polycarbonate is undeformable. The only motion will take place towards the expansions of the concavity.

Third. The only mobility alone lies in the horizontal plane with untwisting, it is related to the elasticity of the posterior bar and metal articulation with polycarbonate.

These modifications are made using the software OrtenShape.

Figure 1. in gray shape capture 1 and in red shape capture 2.

Figure 2. In gray partial reconstruction and in red shape capture 2.

Figure 3. In grey final reconstruction with superposition in red of shape capture 3.

On the left, we see here the partial reconstruction with shape capture 2 in grey and shape capture 3 in red. On the right in gray the final design after complete reconstruction.

In the frontal plane, the only mobility occurs in the expansions. In the sagittal plane, there is no mobility. By against shear and derotation are possible depending on the deformation of the metal bar and hinges with the polycarbonate.

Even if the old Lyon brace in polymethacrylate was very rigid, the credit for VERY HIGH RIGIDITY goes to the Italian team of isoco with the Sforzesco brace, which has proven to be effective by avoiding plaster casts for scoliosis over 45°. The merit of the ART brace is the addition of overcorrection to the high rigidity with a global detorsion. It is this overcorrection for small curvatures which explains the average improvement of the in-brace correction.

Polycarbonate characteristics are:

Transparency,

Unbreakable (25 stronger than Polymethacrylate but Hardness like polyethylene),

Lightweight (3 or 4 mm sheet),

No bisphenol A,

Glass transition 147°-155°,

Bending brake till 120°,

Insulation Rvalue 1.43.

The Soft Contact concept is that of the squeeze attachment for cylindrical hay bales. Pressures are spread over the entire cylinder surface; this is contrary to the principle of the push and counter-push of the historical Lyon brace or other three point braces with limited contact areas or internal pads. In the ART brace the shape of the brace is not a straight spine like the Sforzesco or the old Lyon brace, but an overcorrected spine with reverse scoliosis.

The ARTbrace constitutes an asymmetric exoskeleton reverse the scoliosis in which the patient can slide. There are no pads inside the ARTbrace.

Sliding like on a bobsleigh run, makes the ARTbrace a dynamic brace.

In the Horizontal plane, given the multiplicity of planes, the corrections by the 3 points system only operate in a limited number of planes. The local derotation of the apical vertebra in plane geometry is replaced by a global volume Detorsion. of solid geometry. Therefore, the ARTbrace works in an overall untwisting or detorsion.

The mathematical basis of the torso column is the circled helicoid with horizontal generating circle described by the French mathematician Robert Ferréol. The aim is to get not only a straight spine, but a reverse torso shape capture opposite to scoliosis or overcorrection of the scoliosis curvature. This overcorrection is possible only if the vertebral bodies are not distorted. Otherwise, we favor the correction accentuating the asymmetry of pressure on the vertebral body.

In solid geometry, we do no longer speak of rotation (in a plane), but of TORSION. It is the high rigidity of the polycarbonate which allows the Detorsion or untwisting (geometrical and mechanical). The Global detorsion is performed with a fixed sagittal plane. Axial elongation brings the vertebral bodies near the central axis in the frontal plane, and by untwisting the scoliotic spine between the pelvis and the shoulder the horizontal plane is corrected. So, both geometrical detorsion and mechanical detorsion of the cylinder are working together.

The feature of the ARTbrace is an untwisting that occurs between the axillary clamp, like when wearing a child, and the pelvis.

The first mechanism of the geometric detorsion is the translation along the vertical axis by elongating the two ends of the torso column.

The Shape capture of a brace is always performed in elongation along the vertical axis of the spine. In this posture, we dont have any change of rotation.

The means of achieving this elongation, were improved with braces: from the first Sayres plaster cast with head suspension and body weight realizing a bipolar overall elongation, to the new Lyon brace. The axial elongation like mayonnaise tube is achieved by the simultaneous clamp of the two hemi polycarbonate pieces. there is a real extrusion by bringing together the two pieces.

Despite the respect of curvatures in the sagittal plane, the immediate growth in size is on average 1,5 cm.

The problem is: how to get from three shape captures in 2 dimensions, a global detorsion in 3 dimensions.

The biomechanical basis according to Panjabi is the coupled motion behavior of the spine. The shape capture is 2D but the correction is 3D.

The direction of rotation may differ depending on the flexion of the spine in the sagittal plane. When there is a flat back, the initial scoliotic rotation may be increased by the correction in the frontal plane. Restitution of physiological curves in the sagittal plane seems to decrease the scoliosis rotation (Harrison Fryettes laws).

For example, during the shape capture 2 of the lumbar region, the shift is made in lordosis and one can see the automatic untwisting or detorsion of the spine on this thoraco-lumbar curve.

It is the same for the shape capture No. 3 of the thoracic region. When one combines a frontal bending and a sagittal kyphosis, the untwisting or detorsion is automatic and maximal for this thoraco-lumbar curve.

Here is the result of this case 90, with initially thoracic scoliosis of 39° and rib hump of 17° ATR. Excellent in-brace correction with total reduction of the curvature. The sagittal plane is also improved.

Under EOS 3D, detorsion is excellent.

Here is the Clinical picture in brace.

At Risser 5, after 2 years of bracing, the angulation is 13°.

Clinical aspect at the end of treatment after 6 months of night time bracing. The Bunnel ATR is under 10°.

The sagittal plane set in physiological position retrieves the physiological curvatures in the sagittal plane and improves the coupled motion with detorsion.

More recently the EOS system confirms the accentuation of flat back with all current braces. In all braces, the lengthening of the spine by translation along the vertical axis is accompanied by a decrease in lordosis and an accentuation of the flat back . The EOS system allows to quantify these changes with a loss of 13° of lordosis for the Boston brace and accentuation of the flat back of 3° for the TLSO Chêneau brace.

The ARTbrace is the only brace not to aggravate the loss of lordosis and flat back

Here is an example of in-brace correction of the flat back. This correction may improve during treatment.

The second mechanism is the mechanical detorsion which is carried by the entire external surface of the thorax. The brace will correct the thoracic and pelvic deformity, but especially move the volumes. The faces of the solid obtained from the cutting planes are called bases of the trunk, and the distance between the two cutting planes is the height of the trunk. The lateral surfaces of this solid are not necessarily planar, but are hyperbolic paraboloids.

The two hemi-pieces of ART are indeed hyperbolic paraboloids, adding "Pringle effect" and mechanical detorsion obtained by the detorsion of shape captures 2 and 3.

The tightening at the thoracic basis is essential. The ratcheting closure allows very precise control. The more the brace is tight, the more the detorsion of the spine will increase.

Overall detorsion or untwisting is the sum of the translation along the vertical axis, (tube mayonnaise effect), and the average of all the segmental rotation around the vertical axis.

The EOS 3D system automatically calculates the rotation for each vertebral segment.

The Torsion is the sum of all the segmental rotations. We can calculate the overall in-brace derotation or untwisting. In this case, 30 % improvement.

Classification is very simple for ARTbrace.

For the ARTbrace, we have only two protocols adapted to a single curvature or to a double major scoliosis.

Protocol 1. With two curves, the horizontal thoraco-lumbar plane is fixed and untwisting is independently performed at the thoracic and lumbar level. The two shifts are performed in opposite direction.

Protocol 2. When there is one curvature, the maximal untwisting occurs in the horizontal plane. The two shifts are made in the same direction.

By cons it is the Regional shape capture with endless combinations correcting in the frontal and sagittal plane, that will perform precise adjustment of the brace for every scoliosis. All children have a different scoliosis and no classification can fit all situations.

The ARTbrace is the brace with the lowest impact on FVC, thanks to the easily removable top strap.

Asymmetric braces reduce Forced Vital Capacity less than symmetric due to the expansion in the concavities. Here we see the expansion during breathing movements.

One characteristic of the ARTbrace is the baby-lift which releases the anterior sterno-clavicular region. Here we see the benefit of detaching the top scratch to facilitate high thoracic breathing. Spirometry is performed by detaching the upper scratch.

In plaster cast, the immediate reduction of the vital capacity is 37%, secondarily improved by physical therapy.

In-brace, the FVC reduction, ranges from 22 to 14% per international publications.

Spirometry tests were performed using the Contec SP10.

The first results show a limitation of the Forced vital capacity of 7%, but an improvement in peak flow of 6%, which means that an asthmatic should breathe better under ARTbrace.

The ARTbrace can be used at all ages of life. It replaces the serial casting of early onset scoliosis and is currently is the only corrective brace for adult scoliosis.

The ARTbrace with 3 mm polycarbonate can be used to replace the serial casting of early onset scoliosis. In this case, serial casting was a failure and I see the girl with 95° Cobb angle.

MD and CPO are doing their best, but, the correction was limited to 60° with a Chêneau brace.

For infantile scoliosis, we use the CAD/CAM mirror technique.

You can compare the result in Cheneau brace and in ART in the frontal plane.

But also in the sagittal plane with a better balance.

The day after fitting the brace, Adele was playing toboggan in the park.

If ART is providing excellent for replacing serial casting of infantile scoliosis, it can also be used in adults with the same thickness of 3 mm.

The ARTbrace is also a corrective brace for Adult Scoliosis. In this case, the decompensation occurred at 50 years: 28 years after surgery. The night after brace delivery, the pain disappeared.

The patient feels better balanced and there is an improvement in the thoracolumbar kyphosis.

Even if there is nonunion, we note with EOS 3D that the lumbar area underwent a global detorsion of about 25°. This is the proof that ART is a Detorsion brace.

In conclusion, the amount of innovation is such that one can speak of revolution in the field of scoliosis bracing. The results will confirm these theoretical concepts with an in-brace correction which was capped at 40% during the past 50 years and currently is 70% on average.


Pre Meeting SOSORT 2015 - Katowice

The high rigidity is traditionally used in Lyon for over 40 years. Polymethacrylate was directly replaced the first steel leather Lyon brace.

We shall describe the new concepts, their involvement in the realization of the brace and the results obtained using these new concepts.

 

Many concepts have succeeded in recent years, they were all based on a 3-point system with varying elongation along the vertical axis.

 

The new Lyon brace derives from previous braces. It combines high stiffness (HR) and asymmetry like Chêneau brace.

 

This asymmetry is obtained by a segmental mold that includes 3 stages:

1. Auto-active axial elongation and sagittal positioning of the pelvis

2. Shift and lumbar lordosis

3. Shift and thoracic kyphosis

 

A visual control back and profile is essential

 

The alignment is made along the line of gravity at the center of Dubousset’s balance cone.

Children often have a pelvic anteversion which must be corrected. Instead, adults are in pelvic retroversion,

 

Mold n° 2 made with shift and lumbar physiological lordosis under visual control

 

The shift defined by Min Mehta is a translation to the concavity and an extension. The head is no more on the gravity line.

 

During Min Mehta’s presentation, we can see an imbalance of the C7 plumbline towards the concavity.

 

This imbalance must be corrected when making molding. On the video control, the head is on the gravity line.

 

Theoretically, the axillary and pelvic clamps are located on the same vertical.

 

In the sagittal plane, lordosis is controlled.

1. It can not be a thoracic kyphosis without lumbar lordosis

2. The major defect of current 3 points braces is the reduction of lordosis

 

The major reduction lies in lordosis.

 

Molding 3 is performed in thoracic kyphosis and shift.

1. It is impossible to make the thoracic shift without specific positioning of the upper limb of the concave side. Spontaneously, the child tilts his head to the convexity.

 

The translation in the frontal plane is facilitated by the positioning of the concave upper limb

 

As for the lumbar region, the axillary and pelvic clamps are on the same vertical.

 

Then we begin the kyphotization which will be guided by the hands of the operator. The most common fault is the associated lumbar kyphosis which should be avoided.

 

The second step is the superposition of the three shapes. It is this superposition that performs overall untwisting of the spine in the opposite direction of the scoliosis.

1. The sagittal plane is fixed. The posterior bar reproduces exactly the lordo- kyphosis we wish to give to the patient.

2. The frontal plane reproduces the correction obtained by the shift. Polycarbonate is undeformable. The only motion will take place towards the expansions of the concavity

3. The only mobility alone lies in the horizontal plane with untwisting, it is related to the elasticity of the posterior bar and metal articulation with polycarbonate.

 

On the left we see here the superposition of molding 2 in grey and molding 3 in red. On the right in gray the final design.

 

1.In gray molding 1 and in red molding 2
2.In gray molding 1 + 2 and in red molding 2
3.In grey final molding 1 + 2 + 3 and in red molding 3

 

There are no mobility in the sagittal plane due to the rigidity of the polycarbonate. But there is a mobility along the vertical axis in shear and rotation.

The ARTbrace is insensitive to little imbalances in the pelvis under 2 cm and it is sometimes possible to correct a pelvic rotation by adjusting the lower ratcheting buckle closure.

 

The new Lyon brace is to date the only improving scoliosis flat back. This improvement is immediate on the in-brace Xray and continues at the 1 year check.

 

The vertical axis is the only one that allows the derotation in the horizontal plane and the global detorsion with untwisting.

 

When we put in place the two lateral polycarbonate hemi-shells, the adjustable and very precise axillary and pelvic clamps makes a “push up” immediate effect.

The increase of height noted by parents is an average of 1.5 cm. This results in an untwisting as a spring that is stretched.

 

The brace makes an axillary clamp, like when wearing a child.

This clamp must be as high as possible because if too low it may limit chest expansion,

 

The very precise control of both axillary and pelvic clamps facilitates immediate adjustment and adaptation during growth.

As former Lyon brace, the ARTbrace is renewed every 7 cm in height and every 7 kg of weight gain.

 

In addition of both axillary and pelvic clamps constituting a fixed point, there is a thoracolumbar clamp adjustable by a very precise ratcheting buckle closure.

This costochondral thoracolumbar clamp is located at the junction of the frontal muscle chains. It is fixed in the double scoliosis curves S shaped. It moves in a horizontal plane in derotation only for thoracolumbar curves C shapes

 

Overall derotation or untwisting is the sum of the translation along the vertical axis (push up effect) and the rotation around the vertical axis induced by asymmetry.

 

The mathematical basis of a twisted column is a circled helicoid with horizontal generating circle (perpendicular to the axis)

 

The torso column in opposite direction of initial scoliosis can totally reverse the curve when there is no deformation of the vertebral body

 

Unlike other braces, no specific classification is required for ARTbrace. We distinguish scoliosis with one curvature C shaped and double curvature scoliosis S shaped.

The aim is to realize the inverted twisted column.

 

1.With two curves, the horizontal thoraco-lumbar plane is fixed and untwisting is independently performed at the thoracic and lumbar level. The two shifts are performed in opposite direction.
2.When there is one curvature, the maximal untwisting occurs in the horizontal plane. The two shifts are made in the same direction.

 

In case of high thoracic curve, you can tilt the axillary wrench with rotation on the sagittal axis to correct and rebalance shoulders.

 

The end result of a brace treatment is based on two parameters:

1. Immediate in-brace reduction

2. Compliance with tolerance of the brace.

 

Several elements improve the tolerance of the ARTbrace:

1, The aesthetic qualities of the transparent, lightweight brace, the insulating quality (less perspiration than polyethylene)

2. Design with no areas of high pressure and pads: soft touch brace

3. The end of the plaster cast before definitive bracing which is very popular for children and their families.

 

The type of contact is a major element of compliance. It can be compared to that achieved for lifting hay bales without tearing the thin plastic wrap that covers them.

There is no longer the high pressure contact created by the multiple 3 points system, but a global untwisting between the two  axillary and pelvic wrenches.

 

Expansions in the concavities are filled when breathing. The advantages are:

1. No limitation of vital capacity.

2. Continuing mechanical action in time. This is the 4th dimension that makes ARTbrace a 4D brace

 


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