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Elastic Strapping Orthosis for Adolescent Idiopathic Scoliosis: A Preliminary Report and Initial Clinical Observations

Smith, Keith M. CO

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JPO Journal of Prosthetics and Orthotics: March 2002 - Volume 14 - Issue 1 - p 13-18
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There are numerous theories as to the etiology of idiopathic scoliosis, but it still remains a mystery to the orthopedic community. Roach cites that 2% to 4% of the population between the ages of 10 and 16 have scoliosis with a ratio of girls to boys being 5:1. 1 In recent research, Wang and colleagues 2,3 have noticed that by removing the pineal gland in chickens, they could cause a scoliosis to develop that resembles adolescent idiopathic scoliosis. Due to its secretion of melatonin, researchers believe there is a strong link between scoliosis and the influence melatonin has on growth hormone. Miller 4 cites numerous authors that link scoliosis and heredity. Somerville 5 suggested that biomechanically a developing sagittal hypokyphosis leads to the coronal and transverse deformities of idiopathic scoliosis. Azegami and colleagues 6 studied the buckling phenomenon from gravitational forces on the spine in standing and concluded it to be the strongest connection to the progression of scoliosis. Although the etiology remains unknown, the best defense against adolescent idiopathic scoliosis is still the prevention of its progression.

Traditionally, the goal for the conservative treatment of adolescent idiopathic scoliosis has been the prevention of progression of the curve magnitude through the implementation of rigid orthoses. 1,7–9 A successful treatment has been accepted to be the prevention of surgery by limiting the scoliosis to below a 40° Cobb angle. Roach 1 cites that successful outcomes were evident in patients who had 50%or greater correction of the Cobb angle in the rigid orthosis. 9 Rigid orthoses such as the Milwaukee, Boston, Atlantic Rim, Charleston and Providence, Wilmington, and Rosenberger have been the accepted protocols for idiopathic scoliosis over the years. Orthotic intervention with these orthoses begins at 20° curves and ends at the skeletal maturity of the spine or if the curve progresses to being a surgical candidate. 10 Rowe and colleagues 11 found that a 23-hour regimen is more successful than the 8-and 16-hour protocols. Although correction is usually obtained while in the orthosis, statistically the majority of patients regress back to their original curve magnitude after weaning from the orthosis at skeletal maturity. 9,12 Carr and colleagues 12 proved that patients progressed back to their original degree value in a long-term study of patients who were thought to be corrected permanently by the Milwaukee orthosis. Each of these orthoses relies on intra-abdominal pressure to decrease the axillary load on the spinal column, thereby causing the abdominal muscles to atrophy. Bunnel et al. 10 suggested doing pelvic-tilt and sit-up exercises to avoid this paraspinal and abdominal atrophy from the total contact orthoses. Watts et al. 13 also recognized the importance of an exercise program out of brace to maintain muscle tone. Lam and Mehdian 14 have reported the importance of spine stability coming from the ability of the abdominal muscles to maintain intra-abdominal pressure. They proposed by looking at prune-belly syndrome (absence of abdominal musculature) that hypokyphosis results from the inability of the spine to remain stable and hyperactivity of lumbar musculature as a result of this lack of intra-abdominal pressure. It leads one to ask the question if intra-abdominal pressure is necessary in the treatment of adolescent idiopathic scoliosis, and further does it actually increase the instability of the spine further? Ferrari and colleagues 15 studied the effect that rigid orthoses had on adolescent idiopathic scoliosis patients in exercise and found that due to its constriction of the thorax, the rigid orthoses did decrease pulmonary volumes and respiratory effort as well as the total lung capacity. Aubin et al. 16 studied the efficacy of the Boston TLSO three dimensionally and concluded that the Boston orthosis shifts the spine and rib cage anteriorly with little derotation and proposed that a more optimal orthosis that applied loads laterally on the convex side and on the anterior thorax opposite the rib hump while keeping the rib hump from moving more posterior would be better. Psychosocial issues often times lead to noncompliancy and failure of the orthosis as well. Orthotists and orthopedists alike are constantly struggling with this issue and trying to maintain a balance between compliancy and function. It is important to try to be functional while at the same time practical. Noonan and colleagues 17 in a study on psychosocial characteristics associated with rigid orthoses found a high incidence of lower self-esteem and body image than control patients. Lindeman and Behm 18 found that low brace compliance among girls was also linked to low self-esteem and self-success expectation.

The dynamic elastic strapping orthosis attempts to gain similar results as the rigid orthoses in the prevention of the progression of the scoliosis. The conservative treatment of adolescent idiopathic scoliosis is concerned with the rotational bony wedging that develops as a result of the scoliosis. Mechanical forces involved during progressive scoliosis cause posterior lateral wedging or simply bony deformation, resulting in stiff structural curves. 19 This is evident by looking at the radiograph and seeing the decreased intercostal space on the concave side and the increase on the convex side. It is this bony deformation that sets the foundation for the dynamic strapping orthosis. This dynamic orthosis is implemented with curves less than 35° Cobb angles and 1 to 2 years before menarche in an attempt to prevent this severe bony deformity from developing.


The strapping mechanism attempts to induce a postural deformity to attain curve correction. 20 It is proposed that this postural disorganization is temporary and disappears post treatment. Postural disorganization can be viewed as decompensation of the spine. This orthosis has its own unique classification system for curve patterns with a different movement for each. The corrective forces are referred to as dynamic movements in clockwise and counterclockwise rotations and tilts, lateral shifts, and inclinations and bends. There are three different types of right thoracic curves, two different types of right thoracic left lumbar curves, two different types of left thoracolumbar curves, and one type of left lumbar curve for a total of eight different curve patterns (Table 1).

Table 1:
Types of curves and corrective movements.

The dynamic orthosis is worn 20 hours out of 24 with two exceptions: First, if the patient is Risser 0, has an upright growth rate of only 2 to 3 mm per month, and the Cobb angle reduces to less than 15° on a supine radiograph, then it is not necessary to wear the orthosis at night. Second, if the patient is at the end of treatment with less than 3 mm per month growth and the Cobb angle remains the same with and without orthosis, then again there is no need to wear it at night. Due to its elasticity and the effects of gravity during the day, exercise is done in the orthosis. The concept is to use dynamic forces to cause the body to work in conjunction with them. Rigid orthoses have used three-point pressure systems, stimulus to withdraw, and the righting reflex principles to achieve correction in the orthosis. The rigid orthoses restrict motion in the spine. Biomechanically, the dynamic strapping orthosis relies on the body to work with the position of the orthosis to increase muscular strength before bony deformation and permanent loss occur. The orthosis is worn until skeletal maturity of the spine just as are the rigid systems.

The rigid orthoses biomechanically use endpoint control on the pelvis and afford correction to the spine. The dynamic orthosis on the other hand includes the shoulders in this relationship with the spine and the pelvis. For example, if we look at a typical right thoracic curve and picture the deformity as it presents in the apical or transverse plane, then we see a clockwise rotation of the thorax with a counterclockwise rotation of the shoulders. Traditional orthoses will push on the inferior rib to the apical vertebrae with opposite coronal plane forces at the axillary and trochanteric regions. The dynamic orthosis, on the other hand, now derotates the thorax into a counterclockwise rotation in relation to the pelvis and then goes a step further and brings the shoulders into the opposite rotation clockwise.

The dynamic orthosis is made up of a pelvic base anchored by canvas thigh bands and peroneal straps. It is these peroneal straps in conjunction with the thigh bands that serve as the anchors or endpoint control of the system. The other major structural component is the bolero, which fits on the posterior extending superior from T4 inferiorly to T12. These two components together serve as the attachment points for the corrective bands. These corrective bands are made of elastic material and therefore have some give to them, which gives them their dynamic nature. For each orthosis, there are four elastic bands working together to maintain the correct movement. Each of these components can be seen in Figure 1 separately, and collectively in Figure 2.

Figure 1:
Spinecor components. A, Pelvic section; B, bolero; C, elastic corrective bands.
Figure 2:
Spinecor orthosis fitted.

This system is not only a dynamic orthosis, but by looking at Figure 3, it can be seen that software is implemented to track clinical, postural, and radiological factors to determine the classification of the curve(s). The clinical aspect is concerned with biographical information and trends that exist for a patient, whereas the radiological section deals with Cobb angles found by the two-dimensional radiographs. The postural section involves what is called freepoint, which is the use of ultrasound technology to create a three-dimensional analysis of a patient. This section gives three-dimensional views of the lateral and posterior anterior view as well as an apical view. This section is particularly useful in seeing the rotational aspects of the shoulders, thorax, pelvis, and the patient’s base of support in relation to each other. Raso and colleagues 21 cite that accurate rotation information can only be obtained using techniques of three-dimensional analysis. This freepoint system attempts to gain an accurate three-dimensional picture of the body. It is the author’s opinion that a better system would be one that scans each reference point at the same time. Currently, the freepoint system scans each of a series of points one after the other. The problem is that if the patient moves at all during the scan, then it could be inaccurately read as the position of each segment of the body. Once these data are read into the computer, the software classifies the curve and gives a detailed pictorial description of the fitting of the orthosis and the proper corrective movement. This dynamic orthosis has a different movement for each of the curve types. It is important to note here that this system’s curve types each have one movement, whether there are one are two different curves in the curve type. In a double curve for instance, it has been traditionally accepted to use two different pads or pushes for the curve correction, but with this orthosis, there is one movement of derotation of the shoulders on the pelvis.

Figure 3:
Spinecor software. A, Clinical; B, radiological; C, postural (freepoint system).


Patient A began treatment at Risser sign 0 with a 21° right thoracic curve type I (Spinecor terminology). After the application of the Spinecor, radiographs taken the same day revealed a correction to a Cobb angle in orthosis of 7°. Six weeks later, the patient was seen and the curve correction was 5° in orthosis. Follow-ups 1 year later revealed an out of orthosis Cobb angle of 18°. Patient was a riser sign of 2 and in orthosis correction was now 12°. Eighteen months after the initial application, the patient is now a Risser sign of 4 with a Cobb angle of 20° out of orthosis. This patient is currently being followed to determine the curves’ stability while and post weaning.

Patient B began treatment at Risser sign 0 with a 24°, 29° left thoracolumbar curve type II. After the application of the Spinecor, radiographs taken the same day revealed correction of the curves to 12°, 12° in orthosis. Eight months later in orthosis, radiographs revealed 12 and 17° Cobb angles. One year later, the curve measurements out of orthosis measured 24° and 22°, respectively, with a Risser sign of 0. Of particular interest with this patient is the fact that there was 35 mm of decompensation to the left at the onset and 1 year later it is unchanged.

Patient C began treatment at Risser sign of 0 with a 28°, 18° right thoracic left lumbar curve type I. After the application of the Spinecor, the Cobb angles measured 24° and 18°, respectively. Seven months post initial application, the patient now measures 25° and 20° with a Risser sign of 1.

Patient D began treatment at Risser sign of 1 with a 33° and 19° right thoracic left lumbar curve type I. After the application of the Spinecor, Cobb measurements were recorded of 28° and 19°. Four months later, the curve correction in orthosis was brought down to 22° and 19°. Eight months after the initial application, the patient is now a Risser sign of 3 with out of orthosis Cobb angles of 32° and 22°, respectively.

Patient E began treatment at Risser sign of 3 and a 12°, 26° right lumbar curve. After application of the Spinecor, Cobb measurement of the lumbar curve was brought to 15°. Three months later, the curve correction in orthosis was 18°. After 10 months of wearing the Spinecor, the patient is now a Risser sign of 4 with curve measurements of 10° and 30°, respectively.

Patient F began treatment at Risser sign 0 and a 20°, 20° right thoracic left lumbar curve type I. The initial in orthosis correction was 16°, 11°. One month later, correction in the Spinecor decreased to 22° and 19°. Fifteen months later, the Cobb angles now measure 30° and 24° out of orthosis and 30° and 20° in orthosis. The patient is also having trouble with compliancy and is slightly overweight.

Patient G is of particular interest because of being transferred from the rigid TLSO to the Spinecor due to compliancy. Patient G began treatment with the Boston brace with out of orthosis Cobb angles of 21°, 19° and in orthosis of 12°, 14°, respectively. Seven months later, the patient was fit with the Spinecor at which time the Cobb angles measured in the Spinecor as 13°, 9°, respectively. The patient is now a Risser sign of 4, 14 months post initial application of the Spinecor and has Cobb angles of 20° and 15°.

Patient H had a double major curve right thoracic left lumbar curve that was too rigid for any correction to be attained by the elastic straps. This patient was then molded on the Risser table for a Wilmington TLSO. It is important to note here that the Wilmington did function for correction and patient is maintaining in brace correction.


It can be concluded that single curves respond more favorably than do double curves for in orthosis correction. Smaller curves as well as Risser 0 and 1 curves respond more favorably. So far, only one patient has had greater than 5° of progression, but it must be noted that there has been a problem with compliancy with this patient. This patient has also had weight gain over the last year that makes it difficult to gain much correction in orthosis with the straps.

Patient B is of particular interest because of the decompensation issue. The movement used to achieve correction of this type of curve does not take into account this decompensation and actually goes a step further as to feed into it to gain correction to the top curve. This patient will be followed with particular attention paid to this decompensation.

Patient G is of particular interest due to a good comparison of rigid bracing versus the dynamic. Better correction to the lumbar curve was achieved, and the patient was compliant in wearing the Spinecor. The patient expressed increased comfort and freedom in the Spinecor.

In our group of patients so far, patients E and F have been the only ones who have had compliancy issues. All patients, however, have voiced concern and discomfort from the crotch or peroneal straps. Chafing has not been uncommon from the crotch and corrective bands. Another issue voiced commonly among our patients has been the twisting of the pelvic section, which we refer biomechanically to as the endpoint control for the orthosis. It is the author’s belief that the pelvic section needs changing due to a shifting or a lack of endpoint control and rubbing, but the current study will focus on the existing system. A more optimal sytem might combine the rigid pelvic section comparable to the rigid systems with the bolero and elastic corrective bands of the Spinecor. A strong endpoint control could then be achieved.

Further Research

The study will make use of radiographic films and three-dimensional analyses of the curves with the freepoint ultrasound system at the initial fitting, 6 weeks thereafter, and then every 3 months until the end of treatment. The dynamic straps will be tightened further at each appointment to the optimal amount of force. Comparisons will be made at the end of treatment of curve magnitude, postural disorganization, and compliancy issues.

The study will not be limited to patients that have never worn an orthosis before, but rather will include any patients who transfer from an existing orthosis to the Spinecor system due to compliance as well.

The study will include premenarchal girls with curve magnitudes of 35°. We will observe if the Spinecor can maintain permanent correction post weaning. Second, its success will determine whether intra-abdominal pressure is necessary for scoliosis management. And third, we will look at the effect the decompensated position created for some curves have after weaning out of the Spinecor. Fourth, we will compare similar curve types in the Boston and Wilmington methods to compare how each similar curve type responded in the dynamic orthosis. Finally, we will compare those patients who have withdrawn themselves from rigid orthoses due to compliance and see their correction and compliance in the Spinecor system. We will also address comfort issues in and out of orthosis as compared with the accepted rigid protocols.

This dynamic elastic strapping concept proposes gaining permanent correction with the orthosis in the immature spine maintained post weaning. The data presented here are limited to seven patients, and this permanent correction has not been observed in this group. A larger sample size will answer this theory and give a better understanding of the similarities and differences between the dynamic and the rigid orthoses.


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Spinecor; adolescent idiopathic scoliosis; rotation; tilt; inclination; decompensation

© 2002 Lippincott Williams & Wilkins, Inc.