Principles and Components of Spinal Orthoses

Corset Examples

Sacroiliac corsets are meant to provide assistance to the pelvis only. These garments encompass the pelvis with endpoints inferior to the waist and superior to the pubis ( Fig. 6.1A ). These corsets offer minimal support to the spine and are typically used to create a slight increase in abdominal circumferential pressure for mild conditions. Lumbosacral corsets encompass the pelvis and abdomen. In exerting circumferential pressure, they increase intracavitary pressure in the abdomen and create a semirigid, three-point pressure system for the lumbar spine ( Fig. 6.1B ). The trim lines of the lumbosacral corset are inferior to the xiphoid process and superior to the pubic symphysis anteriorly and extend from the inferior angle of the scapula to the sacrococcygeal junction posteriorly. On female corset styles, the posterior trim line may extend to the gluteal fold to reduce migration in patients with significantly wider hips.

Thoracolumbosacral corsets increase the leverage of the corset system ( Fig. 6.1C ). The trim lines of this style are the same as in lumbosacral garments except posteriorly, where the superior edge terminates inferior to the spine of the scapula. In addition, shoulder straps provide a posteriorly directed force meant to extend the thoracic spine.

Thoracolumbosacral corsets serve mostly as a kinesthetic reminder to control motion in the thoracic spine; they do not provide sufficient rigidity to prevent such motion. For this reason, thoracolumbosacral corsets have been discussed as providing trunk support but not motion control.

Components of Conventional (Metal) Spinal Orthoses

The components used to construct most common metal spinal orthoses are typically aluminum alloys that are radiolucent and malleable, yet of sufficient strength to hold their shape. Ideally, orthoses are custom-fabricated to fit specific landmarks so that the devices provide adequate motion control through the best possible leverage. Fig. 6.2 shows some common components.

The thoracic band is located so that the superior edge rests 24 mm inferior to the inferior angle of the scapula. The band may be horizontal across the back or convex superiorly to provide the greatest height at the midline while allowing for freedom of the scapulae. Lateral to each scapula, the component dips inferiorly to allow space for the axilla. The component ends just anterior to the lateral midline of the body or the midaxillary trochanteric line, a line defined by the bisection of the body at the axilla and trochanter.

The inferior edge of the pelvic band rests at the sacrococcygeal junction, at the midline. Lateral to the midline, the component usually dips inferiorly to contain the gluteal musculature. The rationale for this curve is to provide the greatest leverage for the orthosis. This component also ends just anterior to the midaxillary trochanteric line. The paraspinal bars are contoured to follow the paraspinal musculature. On LSOs, the bars may appear vertical and pass from the pelvic band to the thoracic band (see Fig. 6.2 ).

Norton and Brown described an alteration to this pelvic band design that increases motion control at the lumbosacral junction. They described a pelvic section having projections inferior to the lateral bars that terminate in disks resting over the trochanters. A strap that fastens anteriorly is connected to these disks, offering additional leverage in the sagittal plane. The disks increase the leverage for coronal plane motion control as well ( Fig. 6.3 ).

For thoracolumbar styles, the space between the paraspinal bars often narrows toward the superior end to follow the reduction in the coronal diameter of the vertebrae. In TLSOs, the paraspinal bars terminate inferior to the spine of the scapula. The lateral bars follow the midaxillary trochanteric line from the superior edge of the thoracic band to the inferior edge of the pelvic band. The interscapular band is contained within the lateral borders of the scapulae, with its inferior edge superior to the inferior borders of the scapulae. All metal orthoses can be worn with either a corset or an anterior panel of corset material.

Examples of Rigid Orthoses: Conventional Spinal Orthoses and Contemporary Equivalents

Lumbosacral Orthosis: Sagittal Control

An LSO: sagittal control (also known as an LSO: chairback style) consists of a thoracic band, a pelvic band, and two paraspinal bars (see Fig. 6.2 ). The fitting parameters are the same as described for each of the separate components. This device is indicated for reduction of gross motion in the sagittal plane, including both flexion and extension. The control mechanism consists of two three-point pressure systems. Flexion control is achieved via two posteriorly directed forces at the xiphoid level and the pubic level on the corset panel and one anteriorly directed force at the midpoint of the paraspinal bars. Extension control is achieved via two anteriorly directed forces arising from the thoracic and pelvic bands and one posteriorly directed force from the midpoint of the corset panel. An equivalent commercially available LSO that provides sagittal control is shown in Fig. 6.4 . This orthosis uses preformed anterior and posterior acrylonitrile-butadiene-styrene (ABS) plastic panels lined with soft breathable foam. Closures on each side allow for the adjustment of support. The panels can be heated and reshaped to accommodate anatomical contours.

Lumbosacral Orthosis: Sagittal–Coronal Control

The LSO: sagittal–coronal control includes a component of coronal control by the addition of lateral bars. The eponym for this orthosis, LSO: Knight style, refers to Knight, who described a version of the orthosis in Orthopaedia in 1884. The current form of this orthosis consists of a thoracic band, a pelvic band, paraspinal bars, and lateral bars. In addition to the three-point pressure systems described for the restriction of sagittal plane motion, this orthosis adds three-point pressure systems in the coronal plane to limit lateral flexion ( Fig. 6.5 ).

Lumbosacral Orthosis: Extension–Coronal Control (Williams Flexion)

The LSO: extension–coronal control (Williams flexion) is a dynamic orthosis that consists of a thoracic band, a pelvic band, lateral bars, and oblique bars ( Fig. 6.6 ). The oblique bars provide structural integrity. The attachments at the thoracic band and lateral bars are mobile. This orthosis articulates to allow motion in the sagittal plane. As the device is worn, an inelastic pelvic strap is tightened so that free flexion can occur, but extension is restricted. Williams originally described this orthosis in 1937 for the treatment of spondylolisthesis, and the device may still be prescribed for this pathology.

Thoracolumbosacral Orthosis: Flexion Control (Hyperextension Orthosis)

The TLSO: flexion control (hyperextension orthosis) is commercially available in various styles and sizes from a number of manufacturers. When worn, the orthosis restricts flexion of the spine. Control is achieved through a single three-point pressure system. The system applies two posteriorly directed forces, one at the sternal pad and one at the suprapubic pad, and an equal but opposite anteriorly directed force from the lumbar pad ( Fig. 6.7 ). When donned, the sternal pad rests half an inch below the sternal notch and the suprapubic pad rests half an inch above the symphysis pubis. One style consists of an aluminum frame with pads at the pubis, sternum, and lateral midline of the trunk. This TLSO: Jewett style is named for Jewett, who described the device in 1937 ( Fig. 6.8 ). This prefabricated device consists of an anterior and lateral frame with pads attached to the sternal and suprapubic areas, as well as laterally. A posterior thoracolumbar pad is attached to a strap that extends to the lateral uprights and is used to adjust the tension of the device. Other styles provide similar motion control, such as the cruciform anterior spinal hyperextension (CASH) orthosis ( Fig. 6.9 ). Also prefabricated, the device consists of an anterior frame in the form of a cross, from which pads are attached on a horizontal bar at the sternal and suprapubic areas. A thoracolumbar pad is attached to the horizontal bar and adjusts the tension of the device. When comparing surgical management to nonsurgical bracing with a hyperextension orthosis for single-level closed compression fractures from T11–L2, with no fracture dislocation or pedicle fractures and no other major organ system or musculoskeletal injuries, both modalities were similar but hospital charges were four times higher in the operative group. It should be noted that these charges are not based on newer, minimally invasive surgical approaches.

Thoracolumbosacral Orthosis: Sagittal Control

The eponym TLSO: Taylor style is named for Taylor, the New York orthopedist who described it in 1863. The orthosis consists of a pelvic band, paraspinal bars, an interscapular band, and axillary straps ( Fig. 6.10 ). This orthosis provides two three-point pressure systems in flexion and extension for the thoracic and lumbar spine. The interscapular band provides one of the anteriorly directed forces to limit extension, and the axillary straps provide one of the posteriorly directed forces to reduce the range of motion into flexion.

Thoracolumbosacral Orthosis: Sagittal–Coronal Control

The combination TLSO: sagittal–coronal control has the apt eponym TLSO: Knight-Taylor style. It is fabricated with a thoracic band, a pelvic band, paraspinal bars, lateral bars, an interscapular band, and axillary straps ( Fig. 6.11A ). Through these components, the orthosis limits flexion, extension, and lateral flexion of the thoracic and lumbar spine. The three-point pressure systems in the sagittal plane for the TLSO: sagittal–coronal control are shown in Fig. 6.11B . The commercially available orthosis from Orthomerica provides similar sagittal–coronal control ( Fig. 6.12 ). Its padded frame, similar in shape and contour to a traditional Knight-Taylor orthosis, provides sagittal and coronal motion restriction for the spine.

Thoracolumbosacral Orthosis: Triplanar Control

A variation of the Knight-Taylor orthosis, the TLSO: triplanar control consists of a thoracic band with subclavicular extensions, a pelvic band, paraspinal bars, and lateral bars. The inclusion of subclavicular extensions, which are colloquially referred to as cowhorn projections, adds transverse plane control to this orthosis. As a person attempts right or left rotation of the thoracic spine, counterforces from the thoracic band and subclavicular extensions limit this motion ( Fig. 6.13A ). One example of a commercially available triplanar control TLSO is shown in Fig. 6.13B . This orthosis has been shown to be similar in effectiveness to the TLSO: triplanar control and to be quite comfortable for the patient.