The Boston Brace system (Figure 3.4, step 14, Figure 3.5 and 3.6, Boston Brace International, Avon, MA) is commonly used in North America and Europe for the treatment of adolescent idiopathic scoliosis. The brace is made from a prefabricated module or made to measure from a plaster cast or measurements. A prefabricated brace is trimmed to the needs of the patient and fitted with prefabricated pads in order to correct coronal plane curves and vertebra rotation. The Boston braces (TLSO and LSO models) have a hard polypropylene outer shell with a soft plastazote foam lining (or Aliplast). This lining includes a soft roll that fits over the iliac crests. The modules are available in thirty-six sizes. Circumferences taken at the waist, ASIS, xiphoid and hips determine which module is necessary (Emans et al., 1986). The made to measure Boston brace is fabricated from a positive mould that is obtained from a plaster cast of the patient.
The soft inner lining enables a very intimate fit to be achieved between the patient and the brace. The “grip” on the pelvis provides a firm foundation from which corrective forces can be applied to the spine. The brace is designed to be active. Areas of relief are provided opposite the sites of corrective force in order to allow the patient to pull the spine away by active muscular effort. The brace also has a 15-degree lumbar lordosis built into it (Emans et al., 1986).
Brace design is critical and the aim is to convert a pre-fabricated module into an individual orthosis made for the special needs of one patient. In order to achieve this, a “blueprint” is done on the patients X-ray to facilitate the transition between an abstract design and a finished product.
Anterior View - Boston Brace (Boston Brace International).
TLSO BOSTON BRACE BLUEPRINT (Boston Brace International).
The TLSO Boston brace blueprint will determine the trimlines of the brace and also the position of corrective pads. The most recent patient X-ray should be taken. It should be orientated so that it is being viewed in the posterior anterior view. The centre line is then drawn (figure 3.4, step 1).
Pelvic obliquity is then measured by drawing a line across the top of the iliac crests (figure 3.4, step 2). If there is a pelvic unbalance then an extension and/or pad may be required on the low side. The individual angular values of each vertebra and null points of the curves are then identified (figure 3.4, steps 3 through 5). The Cobb angles are measured as described in the methods section. The position of the crest rolls is marked on the X-ray at the level of L2/L3. The module outline is then drawn onto the X-ray with the posterior opening being equal to the width of the fifth lumbar vertebra (figure 3.4, step 6). Determine the location of the trochanter extension, by placing it on the side toward which L5 is tilted (figure 3.4, steps 7 through 9).
The position of the corrective pads should then be determined and marked on the X-ray. The lumbar pad should be placed on the convex side of the lumbar curve with the top of the pad being just below the null point for the lumbar curve (figure 3.4, step 10). The corrective pad position for the treatment of a thoracic curve is determined by the position of the null point of the curve (figure 3.3, step 11). The pad is positioned on the lateral aspect of the brace. Pressure is applied to the ribs below the apex of the thoracic curve. The pad should not extend above the rib of the apex vertebra.
Once the pad positions have been determined then the lateral trimlines are also determined. The superior trimline is also determined by the presence and size of thoracic curvature. If the patient has a lumbar curve, only then should the lateral trimlines not progress above the iliac crest rolls. In the presence of a thoracic curve, a high axillary extension is required on the concave aspect of the curve in order to produce the third point of pressure while stabilising the brace on the trunk (figure 3.4, step 12). An axillary pad may be required if a trochanteric pad is being used. A “window” is then drawn below the axillary extension extending to the superior aspect of the iliac roll. This “window” would allow the ribs to move laterally due to the pressure being applied by the thoracic pad to the thoracic curve.
Lumbar and thoracic derotation pads can then be marked in the case that lumbar and thoracic rotation is present. If the pelvis is stiff and rotated, thus an ASIS pad will be needed to stabilise the pelvis (figure 3.4, step 13). The Inferior trimlines are determined by pelvic obliquity and the lumbar curve. If there is no pelvic obliquity the brace should be 1cm superiorly in relation to the greater trochanter. Trochanteric extensions should extend distally beyond the greater trochanter.
The whole module is then placed onto the patient. Donning should always be done with the hips and knees in slight flexion. Anterior and posterior trimlines are determined at this stage. The superior anterior trimline should not impinge on the bust of girls and should be clear of the nipples in boys. An apron is drawn onto the brace. The width of the top of the apron is 75% of the width of the chest section. The inferior apron is positioned at the level of the iliac rolls and is 50% of the total width at this level. The inferior anterior trimline should allow comfortable sitting without impingement of the thighs. The central anterior aspect should not be higher than the level of the pubis.
The superior posterior trimlines should be slightly below the level of the inferior angle of the scapula (approximately the level of T8). The trimline flows postero-laterally descending sharply to the top of the iliac crest pad to join the base of the crest pad anteriorly. If there is an axillary extension the posterior trimline will flow into the height of the extension. The inferior posterior trimline should allow comfortable sitting but should be 1-2cm from the chair when sitting (Emans et al., 1986).
The brace is removed and trimmed accordingly (figure 3.4, step 14). The pads are positioned within the brace according to the blueprint. Straps are applied and the brace is re-donned. Any minor adjustments are then made to increase comfort. The fabrication of the brace is then complete.
The indications for the TLSO Boston brace treatments are:
1. Progressive scoliosis with lumbar and thoracolumbar or thoracic curves between 20-50 degrees Cobb angle.
2. Similar characteristics as mentioned, however with curves that are greater than 50 degrees Cobb angle, in which cannot be operated on for specific medical reasons.
The indication for the LSO Boston brace treatment is:
1. Progressive scoliosis in which the curve is below T8, such as low thoracic curves, thoracicolumbar and single lumbar curves.
Figure 3.4 TLSO Boston brace blueprint, Steps 1 through 4.
Figure 3.4 TLSO Boston brace blueprint, Steps 5 through 8.
Figure 3.4 TLSO Boston brace blueprint, Steps 9 through 12.
Figure 3.4 TLSO Boston brace blueprint, Steps 13 and 14.