COMPARISON OF SURFACE TOPOGRAPHY AND X-RAY VALUES DURING IDIOPATHIC SCOLIOSIS TREATMENT USING THE CHÊNEAU BRACE
(THE CHÊNEAU BRACE SYSTEM)
Grant I. Wood
Research Institute for Health
School of Health Care Professions
University of Salford, Salford, UK
Submitted in fulfillment of the requirements of the Degree of Master of Science,
April 2003
Abstract
Brace Studies
3.3 ORTHOTIC TREATMENT
3.3.1 BRACE TREATMENT FOR IDIOPATHIC SCOLIOSIS
Charter 3, section 3.3.1 Literature review of scoliosis bracing, Master degree by thesis, Wood, 2003.
I) TLSO BOSTON BRACE STUDIES
Willers et al., (1993) presented the long-term effect of TLSO Boston brace treatment of the Cobb angle, vertebral rotation, rib hump and translation of the apical vertebra, in idiopathic scoliosis. Computed tomography measurements were completed before the start of treatment with the TLSO Boston brace and subsequently after bracing during an 8.5 years mean follow-up in 25 patients with idiopathic scoliosis. At follow-up, the pre-treatment Cobb angle, vertebral rotation, rib hump and the translation were not significantly decreased. As a result, this study demonstrated that the TLSO Boston brace does not improve, however prevents progression of the Cobb angle, vertebral rotation, rib hump and translation in idiopathic scoliosis. Willers et al., (1993) claimed that the reduction of the sagittal diameter was noteworthy and may be of importance for cosmesis and pulmonary function.
Katz et al., (1997) presented a study of 319 patients with adolescent idiopathic scoliosis treated with either the TLSO Boston brace or a Charleston bending brace. The results found that the TLSO Boston brace is more effective than the Charleston bending brace, both in preventing lateral curve progression and in avoiding the need for surgery. These finding were most notable for patients with curves of 36 to 45 degrees Cobb angle in whom 83% of those treated with a Charleston bending brace had curve progression of more than 5 degrees, compared with 43% of those treated with the TLSO Boston brace. As a result, Katz et al., (1997) recommend the TLSO Boston brace and that the Charleston bending brace should be considered only in the treatment of smaller single thoracolumbar or single lumbar curves.
Goldberg et al., (1993) reported two groups of 32 girls with adolescent idiopathic scoliosis, one group was treated during late onset of idiopathic scoliosis with the TLSO Boston brace and the second group was untreated. The groups were based on curve size, location, and age at diagnosis, furthermore, all were Risser sign 0 at diagnosis. Goldberg et al., (1993) found that there was no statistically significant difference between the groups on any parameter of curve progression (Cobb angle and vertebral column rotation). Therefore, doubts were raised about the efficacy of spinal orthoses in modifying the natural history of late-onset idiopathic scoliosis and removes the ethical problems inherent in a prospective trail in which the only treatment permitted to the control group is surgery.
There are numerous studies on the effectiveness of braces in preventing the progression of the deformity, by taking the Cobb angle as the evaluated parameter, and occasionally the axial rotation angle as well (Mellencamp et al., 1977; Hopf and Heine, 1985; Liljenqvist et al., 1998) but the majority are not conclusive for several reasons. These reasons are related to the design of the retrospective studies, the heterogeneity of the specimens, including males, females, juvenile and adolescent scoliosis, with initial Cobb angles and also with a very variable initial bone age. The conclusive study on the effectiveness of the brace in preventing the progression of the Cobb angle is the study directed by Nachemson and Peterson, (1995). This is a prospective, controlled study, in which, patients were observed and placed in the control group, or treated by electro-stimulation or with a TLSO Boston-type brace. Although, TLSO Boston brace appears effective in preventing lateral curve progression, it does not necessarily mean 3D correction.
II) MILWAUKEE BRACE COMPARED WITH THE TLSO BOSTON BRACE
Long-term studies of both the Milwaukee and TLSO Boston brace have demonstrated that the main effect of orthotic treatment is to produce a curve that is only a few degrees better than that of the original deformity (Edmondson and Morris, 1977; Mellencamp et al., 1977). Therefore, it is assumed that bracing prevents deterioration but does not convert major deformities into normal physiological shapes.
III) TLSO BRACES COMPARED WITH NATURAL HISTORY
Miller et al., (1984) studied 255 female patients with initial curvature measuring 15-30 degrees and who ranged in age from 8 to 17 years. These patients were divided into two closely matched groups with 144 patients treated with various types of TLSO bracing and 111 patients going without active treatment. The results after a mean period of 1.9 years, suggested that bracing reduced the overall probability of progression when compared with the untreated group.
IV) TLSO COUPLING EFFECT
Aubin et al., (1996, 1997) reported that orthoses are widely used to treat scoliotic deformities of the trunk, but the way the corrective forces are transmitted from the thorax to the spine remains poorly understood, and several undesired effects such as the reduction of sagittal curvatures or weak derotations are often reported. A biomechanically measurable element model of the trunk was used to investigate the hypothesis that a coupling mechanism exists between the scoliotic spine and rib cage, which may explain incomplete and unexpected results obtained by orthotic treatments. Forces were applied to the model on the rib hump and lateral side of thorax. These biomechanical simulations demonstrated the existence of coupled motions between the spine and rib cage subjected to orthotic loads. Aubin et al., (1996, 1997) showed that reduction of physiological sagittal curvatures (up to 30%) are possibly related to anterior orthotic loads applied on the rib hump. These loads also contributed to increase lateral shift of the spine (up to 7 mm) as well as scoliotic frontal curvatures (up to 4 degrees). Based on these results, another approach was proposed and this consisted of applying loads laterally on the convex side as well as on the anterior thorax opposite to the rib hump, with a system that mechanically constrains the backward movement of the posterior rib hump. This biomechanical model was simulated on four scoliotic patients presenting thoracic curves between 22 and 54 degrees to evaluate its practicability. It was found that derotation of the trunk (7 to 13 degrees) and reduction of frontal curvatures could be done without reducing physiological sagittal curvature. More simulations on different scoliotic configurations are necessary to find the most optimal combination of forces to produce a real 3D correction of scoliotic deformities.
Willers et al., (1993) demonstrated an undesirable effect of a reduction in the sagittal diameter of the thorax caused by the TLSO Boston brace. Labelle et al., (1996) and Aubin et al., (1996, 1997) reported that the TLSO Boston brace produces a lordotic effect (hypokyphosis) in the thoracic region as a result of the coupling of the spine and the ribs of the costal gibbus. This is caused by the forces acting from dorsal to the ventral aspect. The authors Labelle et al., (1996) and Aubin et al., (1996, 1997) have recently proposed a modification of the correction principles, which consists of applying loads laterally on the convex side as well as on the anterior thorax opposite to the rib hump, with a system that mechanically constrains the backward movement of the posterior rib hump. Indeed, these proposed modifications are not very different from those originally proposed by Chêneau, (1990, 1994, 1996a). The correction principles originally proposed by Chêneau in 1979 facilitate correction as a result of the location and size of the forces, as well as the expansion rooms on the opposite side of the convexities, which permit derotation, coronal plane correction and sagittal normalization.
V) CHÊNEAU BRACE STUDIES
A study by Oberthaler et al., (1985) was conducted on 115 patients with idiopathic scoliosis treated with either the TLSO Boston brace or the Chêneau brace. The results found that there was excellent Cobb angle correction of the deformity in both braces. The TLSO Boston brace seems to be better for lumbar and thoracic curves whereas the Chêneau brace lends itself more for thoracic curves or when more than one primary curve is present. It was also claimed that the TLSO Boston brace was effective in treatment of mild hyperkyphosis.
Von Deimling et al., (1995) compared long-term influence of idiopathic scoliosis in 47 patients who wore either the Milwaukee brace or the Chêneau brace with an average follow-up of 7.8 years. It was reported that Chêneau brace had significantly better results. There was a Cobb angle correction of 62% and 38% the patients who wore the Chêneau and Milwaukee braces respectively. The initial correction of the Cobb angle was 35% and 47% of the pre-treatment value in the Chêneau and Milwaukee braces.
Rigo (1999c) reported a retrospective study of 105 patients (mean age of 12.5 years) with progressive idiopathic scoliosis who were treated with the Chêneau brace. Of this group, 44 patients had been wearing other braces from other clinics before the start of treatment with the Chêneau brace. All of these 44 patients presented curve progression even while wearing their previous brace. The major Cobb and torsion angles had a mean of 37 degrees and 17 degrees respectively at the start of Chêneau brace treatment. The major Cobb and torsion angles had a mean primary correction of 31% and 22% respectively. In the group of patients with end results (n=37) the mean initial major Cobb and torsion angles were 36.4 and 16.9 degrees respectively and at follow-up they were 34.1 and 15.7 degrees. The results show high initial Cobb angles at the start of treatment and a low primary correction. The final Cobb angle at a 2-year follow-up, showed a tendency of a loss of correction, without reaching significance. Rigo (1999c) claimed that the Chêneau brace could effectively prevent the progression of the Cobb and torsion angles, even in cases of bad prognosis. In agreement with other authors, these results show better end results with a low initial Cobb angle and high primary correction. The primary correction is less than those of Hopf and Heine, (1985) as well as Liljenqvist et al., (1998) however this could be due to the higher initial Cobb angle and poor effect of previous treatments of lower quality braces producing more rigid curves.
VI) CHÊNEAU BRACE
Dr. Chêneau, inspired by Abbot, fabricated the original Chêneau brace in 1979. The Chêneau brace is commonly used for the treatment of scoliosis and thoracic hypokyphosis in many European countries such as Spain, France, and Germany as well as other countries like Israel and Russia. However, it is not commonly prescribed in North America and the UK.
The brace is fabricated in polypropylene and has an anterior opening with Velcro straps for fastening. The Chêneau brace is defined as a thermoplastic brace modelled on a hyper-corrected positive plaster mould of the patient. The general correction principle is that of detorsion and sagittal plane normalisation, which would correct the coronal and transversal planes, resulting in some elongation of the spine, without any significant distraction force, (Rigo, 1999a).
The objectives of the Chêneau brace are to obtain a three-dimensional correction of the scoliotic deformity, with emphasis not only on the coronal and transverse planes, but also on the sagittal plane (Matthiass and Heine, 1984; Syndikus et al., 1988; Giorgi et al., 1996; Losito et al., 1996; Kotwicki et al., 1999).
The deformation of the scoliotic body consist of (Chêneau 1996a, 1996b):
- The paired convexities and concavities: in an oblique plane the brace reduces the convexities and transfers tissues from the convex humps in the direction of the concave flat areas. All abnormal protrusions with respect to the normal physiological shape must be submitted to pressure.
- Sagittal configuration deformity: often, abnormal thoracic kyphosis and lumbar lordosis is presented in the scoliotic patient.
- Torsion of the pelvis and rotation of the shoulders: the brace must produce a detorsion of the pelvis and derotation of the shoulders.
- The lateral displacement: in a transverse plane the brace establishes a balance of the shoulders and thorax over the sacrum.
Chêneau (1990) provided a number system to indicate pressure and expansion zones on the Chêneau brace. This number system facilitates the identification of important zones on the Chêneau brace, plaster of Paris cast and the patient’s body (figure 3.16a and b). The system lists number 1 through number 43, however some numbers are missing as the evolution of the brace has made them obsolete. The number system is used in all different types of classifications of scoliosis and curves, hence it is not limited to only one type of curve. However, not all the numbers in this number system are utilised in all cases. This is because sometimes a particular number may not be utilised as its corresponding function is not required.
Additionally, the location of the numbers often change from being on the right side of the brace to the left side and vice versa, as each scoliosis case is treated independently. As a result, the locations of these numbers are often determined by the direction of the curve convexity. Therefore the brace design is different for each individual case. The basic location of the pressure and expansion zones using the Chêneau brace number system and their corresponding functions are indicated below.
1: The location of the pressure zone 1 is on the convex side of the thoracic or thoracolumbar curve on the dorsal aspect of the brace. The function of this pressure is for the correction of the thoracic or thoracolumbar curve in the coronal plane and rotation of the vertebral column in the transverse plane.
1´: The location of pressure zone 1´ is on the convex side of the lumbar curve on the dorsal aspect of the brace. This pressure zone is extended to the posterior midline in the case of lumbar hypolordosis, which is for the correction of the deformity in the sagittal plane.
2: The location of the pressure zone 2 is on the convex side of the lumbar curve on the dorsal aspect of the brace. The function of this pressure is for the correction the lumbar curve in the coronal plane and if present, correction of the lumbar hypolordosis deformity in the sagittal plane.
3´: The pressure zone 3´applies a counterforce to the axilla that works on the opposite side to zone 1, which is for the correction of the thoracic and thoracolumbar curve in the coronal plane. Also, in the case of an unbalanced trunk over the pelvis, this force pushes the trunk to the midline of the body, placing it over the pelvis. When retropulsion of the shoulder is present, this force lifts the lower shoulder superiorly.
3: The location of pressure zone 3 is at the same level as 3´, but it is more posteriorly placed to move the retropulsion shoulder ventrally in the sagittal plane.
4: The location of pressure zone 4 is on the ventral aspect of the trunk. This force is placed adjacent to the pressure zone 1. The function of these forces is to work together to reduce the large diameter of the oval shaped thorax, which facilitates the derotation of the thoracic region in the transverse plane.
5: The location of expansion zone 5 is beside the thoracic and thoracolumbar curve and pressure zone 1. The function of this expansion zone is to provide a room or space for the expansion of the trunk, which allows respiratory movement, and permits small voluntary and involuntary movements as well as the patient’s growth. This provides an active mechanism of correction in the direction of derotation and rekyphosis,
5´: The location of this expansion zone is on the concave side of the thoracic curve and is opposite to pressure zone 1. The function of this expansion zone is to provide a room or space for the expansion of the trunk, which corrects the thoracic curve in the coronal plane.
6: The location of expansion zone 6 is on the posterior aspect of the hemipelvis that is in anteversion. This provides a space for the derotation the hemipelvis.
7: The location of expansion zone 7 is on the ventral aspect and is adjacent to pressure zone 3. The function is to provide a large space for the correction of the rotation and hypokyphosis of the thoracic region.
12: The location of pressure zone 12 is in the subclavicular region of the lower shoulder, which is positioned in retropulsion. The function is to facilitate control of the retropulsion shoulder in the sagittal plane.
13: The location of expansion zone 13 is outside the dorsal superior trimline of the brace above expansion zone 5. Its function is to provide an expansion zone for the correction of the thorax.
17: The location of expansion zone 17 is on the dorsal aspect of the brace next to expansion zone and window 5´ . Its function is to provide an expansion zone for the correction of the thoracic or thoracolumbar curve.
18: The location of expansion zone 18 is on the dorsal aspect of the brace above expansion zone and window 5´. Its function is to provide an expansion zone for the correction of the thoracic or thoracolumbar curve.
19: The location of expansion zone 19 is on the breast that is tilted to the high side. The function is to provide a large space for the correction of rotation and hypokyphosis of the thoracic region.
21: The location of pressure zone 21 is on the ventral aspect between pressure zone 4 and pressure zone 2. The function is to connect pressure zone 4 and pressure zone 2. This provides a smooth connection of the pressure zones and forces from the body to the brace, also this gives a more cosmetic appearance.
23: The location of this expansion zone 23 is on the concave side of the lumbar curve and is opposite to pressure zone 2. The function of this expansion zone is to provide a room or space for the expansion of the trunk, which corrects the lumbar curve in the coronal plane.
24: The location of expansion zone 24 is on the dorsal aspect of the brace above expansion zone and window 5´ and ventral to expansion zone 18. Its function is to provide an expansion zone for the correction of the thoracic or thoracolumbar curve
26: The location of expansion zone 26 is outside the dorsal superior trimline of the brace above pressure zone 1. Its function is to provide an expansion zone for the correction of the thorax.
27: The location of expansion zone 27 is on the concave side of the thoracic or thoracolumbar curve, just above pressure zone 3 on the shoulder, which is in the position of retropulsion. The function of this zone is to provide an expansion zone for the shoulder in retropulsion.
30: The location of pressure zone 30 is applied to the greater trochanter on the low side of the pelvic tilt. The function of this force is to work with pressure zone 2, which provide counterforces to pressure zone 41 to move the pelvis upward from its tilted position.
33: The location of expansion zone 33 is on the dorsal inferior aspect of the brace, which is in retroversion. The function is to allow space for the derotation of the hemipelvis, which is in retroversion in the sagittal plane.
34: The location of the pressure zone 34 is on the dorsal inferior aspect of the brace, which is in anteversion, at the level of the gluteus maximus. The function of this force is to derotate the hemipelvis, which is in retroversion in the sagittal plane.
35: The location of expansion zone 35 is on the low side of the pelvic tilt, positioned on the ventral inferior aspect of the brace. This is above pressure zone 30 at the level of the iliac crest. The function is to provide room or space for the derotation of the hemipelvis in retroversion by allowing it to move upward.
36: The location of expansion zone 36 is on the ventral side of the body, in which the hemipelvis is in anteversion, below pressure zone 37. The function is to allow space for the derotation of the hemipelvis, which is in anteversion in the sagittal plane.
37: The location of the pressure zone 37 is along the waistline going downward towards the ASIS (anterior superior iliac spine) on the side of the body that has the hemipelvis in anteversion. The function of this pressure zone is to derotate the anteversion position of the hemipelvis in the sagittal plane.
38: The location of the pressure zone 38 is above the symphysis pubis on the same side of the body that has the hemipelvis in retroversion. The function of this force is to derotate the retroversion position of the pelvis.
39: The location of the pressure zone 39 is on the ventral aspect of the brace and is below pressure zone
40. The function of this force is to reduce the distance of the oval thorax, this corrects the hypokyphosis in the sagittal plane by causing flexion of the thoracic vertebral column.
40: The location of the pressure zone 40 is on the ventral aspect of the brace and is adjacent to the pressure zone 1, which is on the convex side of the thoracic or thoracolumbar curve. The function of this force is to reduce the distance of the oval thorax, this corrects the hypokyphosis in the sagittal plane by causing flexion of the thoracic vertebral column.
41: The location of the pressure zone 41 is in the iliac fossa, on the lateral aspect of the hemipelvis, which is on the high side of the pelvic tilt. The function of this force is to work with pressure zone 30 and pressure zone 2 to provide a 3-point pressure system that lifts the low contralateral hemipelvis.
43: The location of the pressure zone 43 is underneath the lower positioned breast, which lifts it to the level of the contralateral breast. In the case of a male patient, this zone is designed the same way as the female patient, however it would not have to be as large. The function of this zone is to balance the lower positioned breast with the contralateral side.
Thoracic Section
Pressure zones 1 and 4 reduce the larger diameter of the thorax and increase the smaller diameter. These actions reduce the humps and fill-in the flat areas. This dorsal displacement of the spine, fills in the dorsal expansion zone 5 (figure 5a), as a result, this reduces the thoracic hypokyphosis. The dorsal thorax is not in contact with the brace, however, the space is important for respiratory movement, and permits small voluntary and involuntary movements as well as the patient’s growth. This provides an active mechanism of correction in the direction of derotation and rekyphosis.
Lumbar Section
The lumbar section consists of pressure zones 2 and 1´ , which are applied one vertebra above and one vertebra below the apex of the lumbar curve. These dorsally located pressures are a continuation from the ventral pressure zone 4. Pressure zone 1´ extends almost to the posterior midline when lumbar hypolordosis is present and thus, it is needed to influence normal lumbar lordosis. In the case that it is not required to increase the lordosis, pressure zone 1´ is not utilised, and the pressure zone 2 extends less to the midline. The shape of these pressures are smooth and sufficiently deep enough to apply a corrective force to the lumbar curve.
The function of pressure zone 2 is for the lumbar curve correction in the coronal plane. The 3-point pressure system is made up of pressure zone 2 and the counterforces from pressure zones 1 and 41. Pressure zone 2 is applied above and below the apex of the curve, pressure zone 1 is a counterforce which is applied to the opposite side of the lumbar curve and is located cephalically to the apex. Pressure zone 41 is also applied to the opposite side of the lumbar curve and is located caudally to the apex, which is below the iliac crest, as shown in figure 3.21.
Figure 3.21 The lumbar curve is corrected by the 3-point pressure system, which consists of pressure zones 2, 1 and 41. These forces are represented in the figure as 2, 1, and 41 respectively, (Master by thesis, Wood, G 2003).
Dr Rigo’s patient and brace with correctional Xrays (see right)
X-Rays Out of (left) and In (right) Dr. Rigo’s Brace
Pelvic Section
The pelvic section is designed to correct pelvic tilt and pelvic torsion. The pelvic tilt presents as a protrusion of the pelvis. Usually, the hemipelvis is higher on the thoracic convex side. The pelvic tilt is corrected by a 3-point pressure system that consists of pressure zones 41, 2 and 30 and expansion zone 16. The location of pressure zone 41 is on the iliac fossa, which is on the high side of the pelvic tilt. Pressure zone 2 is on the opposite side to pressure zone 41 and is located approximately 3cm above the iliac crest. Pressure zone 30 is on the opposite side to pressure zone 41, and is located on the greater trochanter. Expansion zone 16 has a window and is required on the low side of the hemipelvis. This provides a space for the hemipelvis to move into during correction.
Pressure zone 41 has a concave shape, which mimics the anatomical dimple-shape of the iliac fossa. Its inferior lateral trimline is at the caudal aspect of the iliac fossa. The pressure zone 30 is shaped so as to apply slight pressure on the greater trochanter, without causing discomfort. The trimline extends to the greater trochanter so that the counterforce works with pressure zone 2. Pressure zone 2 is shaped as previously mentioned in the lumbar section. The pelvic grip of the brace is designed so that it is higher on the side in which the pelvis is tilted lower, hence it has an asymmetrical shape.
The functions of these forces are to work together as a 3-point pressure system. Pressure zone 41 pushes the contralateral hemipelvis upward and the expansion zone 16 provides a space for the hemipelvis to move into for correction, (figure 3.22).
Pelvic torsion consists of iliac rotation and pelvis transversal rotation. The iliac rotation refers to a position of relative anteversion of the concave side of the lumbar curve and retroversion of the convex side of the lumbar curve. Anteversion is an abnormal position of the hemipelvis that is rotated and torsioned anteriorly therefore the ASIS is more prominent than usual, (figure 3.23). The contralateral hemipelvis would be in retroversion. Retroversion is an abnormal position of the hemipelvis, which is rotated and torsioned posteriorly therefore the ASIS is less prominent than usual, (figure 3.24). The contralateral hemipelvis would be in anteversion.
Rigo and Chêneau (1997, 2000) reported that this could be the consequence of passive tension of the lumbar fascicles of the erector spinae (longisimus thoracis and iliocostalis). Rigo (1999a) found that sometimes, combined or substituting iliac rotation causes a true three-dimensional iliac torsion (a bone deformity). Iliac rotation is corrected by pressure zones 37 and 34 as well as expansion zones 36 and 6 on the hemipelvis that is in anteversion. Pressure zones 38 and 2 as well as expansion zones 35 and 33 are applied to the hemipelvis that is in retroversion. Also by correction of the lumbar curve, the pelvis automatically assumes an anteversion position and therefore corrects itself.
The hemipelvis that is in anteversion, has its ventral inferior trimline of the brace that extends inferiorly to cover the ASIS and pressure zone 37. However it is not as low as the contralateral side because expansion is required by expansion zone 36 for the correction of anteversion. The dorsal inferior trimline, for the same hemipelvis, extends inferiorly to the gluteus maximus. This trimline is sufficiently inferior to apply pressure zone 34.
The hemipelvis that is in retroversion, has its ventral inferior trimline of the brace that extends inferiorly to above the symphysis pubis to apply pressure zone 38. This is much lower than the contralateral side because pressure is required by pressure zone 38 for the correction of retroversion. The dorsal inferior trimline, for the same hemipelvis, is higher than the contralateral side because expansion is required by expansion zone 33 for the correction of retroversion. These inferior ventral and dorsal trimlines are asymmetrical and depend on the position of the pelvis.
Figure 3.22 Posterior view of a right thoracic and left lumbar curves in the coronal plane. Pressure zones 41, 2, 30 and expansion zone 16 are represented in the figure as 41, 2, 30 and 16 respectively. The upward moment is represented as M. The thoracic convexity is to the right, therefore the pelvis tilt is to the left side. Pressure zone 41 pushes the pelvis between the two counterforces 2 and 30, therefore M is produced. This moves the left hemipelvis upward into expansion zone 16, as a result the pelvis is levelled, (Master by thesis, Wood, G 2003).