The Rosenberger Scoliosis Orthosis

THOMAS GAVIN*, WILTON H. BUNCH, MD, PHD**,and VICTORIA M. DVONCH, MD***Chicago, Illinois


I

n modern non-operative treatment of idiopathic scoliosis, the low profile orthosis is frequently preferred. Low profile designs have been known since antiquity; however, recently developed orthoses made of various materials claim distinct advantages.

The Rosenberger Scoliosis Orthosis originated in the orthotic laboratory at the University of Virginia by the late Richard Rosenberger. The jacket was initially made of unlined Orthoplast. This orthosis has been used at Loyola since July 1983 by a selected group of patients, yielding impressive results. The molding and fabrication process, presumed mechanism of action of the orthosis, clinical considerations, and preliminary results are presented.

Molding and Fabrication

The Rosenberger orthosis is custom molded over a plaster cast of the patient. The cast is prepared in bi-valved fashion with the patient supine, in order to unload the vertebral column. The patient's knees and hips are then flexed to reduce the lumbar lordosis. The anterior mold is applied from the sternal notch to the pubic symphysis, and from the axilla to the greater trochanter encompassing two-thirds of the trunk circumference. Transverse force is applied through the cast on the apex of the curve and counterforce applied on the contralateral pelvis and axilla. For a right thoracic-left lumbar double major curve, force is applied on the apices of both curves, and countered on the right pelvis and the left axilla. This provides the three- or four-point pressure system needed to reduce some curvature in the cast, and, more importantly, achieves opposition gradients in the mold (Fig. l ). Opposition gradients on the concavity of the curve offer hollow areas for lateral trunk displacement; on the convexity, gradients decrease the distance from an adjustable pad to the lateral wall of the jacket.

After the mold hardens, two compressive straps are secured circumferentially around the superior and inferior borders of the cast. The patient is then asked to stand and a circumferential wrap is made to complete the cast.

A positive model is prepared from the cast and carefully modified. Grooves are placed above the iliac crests for a stable base of support1. Slight reliefs over the crests are added for optimal fit with maximum comfort. A concavity against the abdomen increases intra-abdominal pressure which, correlated with the reduced lumbar lordosis, assists in maintaining pelvic tilt. Lateral opposition gradients are evident. The jacket is vacuum formed from low density polyethylene.

Anteroinferiorly, the trimline is high enough to allow erect sitting without impinging on the thighs. Anterosuperiorly, plastic is trimmed below the breasts. (Fig.2a ) On the concavity of the higher curve, the jacket extends from the greater trochanter to the axilla, and on the convexity of this curve, the trim extends from the greater trochanter to one rib above the apex. Posteroinferiorly, the trim allows 2.5 cm (1 in.) clearance from a firm chair with the patient sitting erect. The superior margin has a unique trimline, featuring a lip for attachment of a thoracic strap, which is placed medial to the axillary trimline. The lip is tapered into a slot over the spinous process of the thoracic apical vertebra (Fig. 2b ). Polyethylene is lined with Thermofoam.

A thoracic corrective strap is placed to contact the rib articulated to the apical vertebra and one rib below, immediately lateral to the spinous process, on the convexity of the curve. The strap follows the two ribs laterally, and is then inserted through the jacket approximately 10 degrees anteromedial to the mid axillary line (Fig. 2c ). The thoracic strap, secured with Velcro laterally, provides an easily adjusted, efficient method to apply transversely force to the thoracic curve.

A conventional lumbar pad is suspended on a movable strap, similar to the thoracic strap. The pad provides a highly adjustable means of transverse loading on the apex of the lumbar curve.

An anterior opening with Velcro closures provides easy donning and adjustment. Thin polyethylene, used as a tongue, minimizes abdominal bulge, a common problem with anteriorly opening orthoses that incorporate intraabdominal pressure. Because of the flexibility of low density polyethylene, a tongue and groove design is needed to aid alignment of the left and right sections of the jacket.

Careful casting, fabrication, and fitting of the orthosis, with meticulously placed forces, are essential to provide the maximum benefit.

Presumed Mechanism of Action

Orthoses for scoliosis should accomplish two goals: a) prevent further progression of the curvature, and b) reduce the existing curve to the maximum limit without creating skin breakdown or intolerable discomfort.

Theoretically these goals are realized by fixing the flexible vertebral column rigidly, thus increasing the critical load at which maximum displacement occurs. Increasing the critical load plays the greatest role in preventing curve progression2.

The Rosenberger orthosis attempts to fix the base of the vertebral column rigidly as do most scoliosis orthoses, by means of a snugly fitted pelvic section3. The high axillary and posterior trimlines should limit column sway although sway is not as completely limited as by the Milwaukee orthosis with its neck ring. Definitive use of high counterforce on the concavity of the curve eliminates dependence on the righting reflex; thus, the orthosis also attempts static endpoint control of the curve to maintain upper thoracic alignment and shoulder symmetry for best appearance.

Transverse loading, presumably the action that reduces the curve, is accomplished by the correct placement of the horizontal vector translated to the apex of the curve, with contralateral control at, or as close as possible to, the endpoints of the curve. The orthosis exerts maximum tolerable dynamic force through the thoracic strap and lumber pad, with the peak force directly at the bisector of the posterolateral quadrant as evident in Figure 2c .

Constant dynamic force is applied to the torso. Consequently, all patients seen at followup, whether Blount's physical therapy program4 was prescribed or not, were able to displace the trunk laterally, thus pulling from the strap or pad to relieve skin pressure. Without the hollow areas on the concave side of the curve, the patient would not be able to pull from the forces actively and would have little or no relief from the constant pressure of the skin. Thus opposition gradients are essential.

If increasing the critical load and transversely loading scoliotic curves are truly important factors in orthotic management of idiopathic scoliosis, and if our methods of achieving these two loads are correct, then the Rosenberger orthosis treats idiopathic scoliosis effectively.

Clinical Considerations

The patient usually must wear the orthosis 23 hours a day, and thus must be well motivated to gain compliance. Low profile orthoses offer better appearance than the Milwaukee orthosis with its neck ring. Nevertheless, if endpoint control of the curvature is primary, curves with an apex of T6 and higher will be treated more effectively with the Milwaukee design, because of greater control of vertebral sway by the neck ring.

Borderline patients who have large curve magnitudes or are barely flexible to be considered orthotic candidates may benefit more from a Milwaukee orthosis. The neck ring provides greater sway control and may increase the critical load more effectively than the low profile. These patients have the lowest critical load because of curve magnitude.

Other criteria used to determine candidacy for the Rosenberger orthosis are the same for the Milwaukee orthosis. Many variables affect the decision and all should be evaluated carefully.

Preliminary Results

The Rosenberger orthosis has been developed recently, precluding long-term results. Nevertheless initial curve reduction may determine the prognosis for the efficiency of an orthosis.

Between July 1983 and March 1985, twelve patients with idiopathic scoliosis were fitted with Rosenberger orthoses through the scoliosis clinics of Loyola. Their ages ranged from 10 years 9 months to 17 years 3 months, with the mean age of 13 years 3 months. Eleven patients were female, six of whom were pre-menarchal at the time the orthoses were fitted.

Four curves were right thoracic, seven were right thoracic left lumbar, and one was right thoracolumbar. The original curves ranged from 25 to 35 degrees, with a mean of 28.1 degrees. Initial reductions achieved with the orthoses ranged from 23 to 100 percent, with a 42.1 percent mean and a 31 percent median. Most patients seemed well motivated, although two did admit to partial non-compliance.

Conclusion

The Rosenberger orthosis applies well established principles to management of scoliosis, particularly adjustable pads for dynamic forces, static contralateral counterforces, and hollow areas for lateral trunk displacement. Although not intended for all scoliotic curves, in our hands, the Rosenberger orthosis has yielded impressive early results.

*Universal Orthopaedic Laboratories, Broadview, IL 60153

**University of Chicago, 950 East 59th Street, Chicago, IL 60637

***Section of Pediatric Orthopaedics, Loyola University Medical Center, 2160 South First Avenue, Maywood, IL 60153

Vol. 21, Nos. 3-4, Autumn-Winter 1996

References:

  1. Bunch, Wilton H., and Robert D. Keagy: Principles of Orthotic Treatment. St. Louis: C.F. Mosby Co., 1976.
  2. Bunch, Wilton H., and Victoria Dvonch: Bracing for Idiopathic Scoliosis-Current Concepts In Press
  3. Bunch and Keagy, op. cit.
  4. Blount WP, and J. Bolinski: Physical Therapy in the Non-Operative Treatment of Scoliosis. Phys Ther 47:919-925, 1967.