Infantile Scoliosis Treatment & Management

There are three management options for infantile scoliosis ^[20] :

• Observation
• Orthosis
• Operation

The decision when to use each of these is based on the rib-vertebral angle difference (RVAD; see Workup), established by Mehta in 1972 (see the image below). ^[21]  The RVAD is a useful guide in distinguishing between resolving and progressive idiopathic infantile scoliosis.

For scoliosis curves with an RVAD of less than 20°, observation every 4-6 months is sufficient. If the RVAD is more than 20° or if it is not flexible clinically (ie, curve cannot be corrected even slightly with different postures, especially lateral bending), then it is considered to be progressive until proven otherwise.

Normally, there are interobserver and intraobserver variations with these radiographic parameters. Corona et al found that even though variations are present in the radiographic parameters of RVAD, Cobb angle, and space available for lung (SAL), these radiographic parameters are useful tools for planning management options. ^[12] According to the authors, even though these parameters are not devoid of variability, they are not excessively skewed, and the RVAD and the Cobb angle are highly useful for accurately and reliably suggesting the best course of treatment.

Management with orthosis is necessary when the curve is considered to be progressive or if a compensatory curve has developed. ^[22]  Various types of orthosis are available for children younger than 3 years. The most commonly used orthoses are the following:

• Hinged Risser jacket
• Plaster spinal jacket (eg, elongation-derotation-flexion [EDF] type ^[23] ) applied under anesthesia
• Milwaukee brace
• Boston brace

The brace should be used for 23.5 hours a day and should be removed only for exercises and swimming. It should be used until skeletal maturity is attained, because curves usually do not progress after skeletal maturity; however, curves may progress despite the use of a brace. ^{[24, 25, 26]}

Spinal deformity in scoliosis progresses during periods of peak growth velocity. The first spinal growth peak occurs at 2 years of age, and the second peak occurs during the prepubescent period.

Operative treatment is usually an option only for children in older age groups (ie, around age 10 y), and segmental posterior wiring to two L-rods without fusion is preferable until combined posterior and anterior fusion can be done. These procedures, however, have been associated with complications in 50% of patients.

Because of advances in instrumentation, pedicle screw instrumentation can be performed for children with further growth potential. ^[27]  In these patients, a growing rod is used, which is associated with fewer complications than surgical fixation using L-rods. The disadvantage associated with the growing rod is that every 6 months the posterior aspect must be opened to lengthen the rod, which increases the risk of infection; however, if the curve is severe or increases despite the use of orthosis, a short anterior and posterior fusion is recommended to prevent crankshaft phenomenon.

Surgical options

The decision whether to operate on a patient with scoliosis depends on many factors, such as the following:

• Time of onset of the curve (early-onset curves most often warrant surgery)
• Degree and site of the curve (a thoracic curve greater than 40° or a lumbar curve greater than 60° in a child aged 10-12 years often requires surgery)
• Response to conservative treatment with a brace
• Rate of progression of the curve
• Acceptability of the cosmetic appearance of the spine to parents and patient

Growing rods without fusion is preferable until combined posterior and anterior fusion can be done. Growing-rod systems (eg, pediatric Isola instrumentation) may be utilized to prevent curve progression; extensions are needed every 6 months to keep pace with the child's growth until the child has adequate trunk length, which is usually between the ages of 11 and 15 years.

Once skeletal maturity is reached, the child needs a definitive fusion ^[28] ; this involves removal of implants and reinstrumentation. If there is evidence of congenital problems or thoracic insufficiency, another type of growing-rod system (eg, the vertical expandable prosthetic titanium rib [VEPTR]) may first be used. ^{[29, 30, 31, 32, 33]}

There is, however, an alternative in very young children in whom the curve progresses: application of a localizer cast. ^{[34, 35]} A localizer cast can hold the curve and prevent it from progressing further. However, application of localizer casts is a dying art, and it requires proper care and frequent change of the plaster.

The localizer cast is applied to the child's trunk under general anesthesia, with traction to the head and neck via a sling across the mandible and the occiput and countertraction to the pelvis through another sling. The plaster jacket is applied around the trunk, with care taken to ensure that there is enough room for hip movements by stopping just below the level of the iliac wings. Superiorly, the plaster goes around the axillae, leaving the arms and the shoulders free.

If needed, in higher thoracic curves, a neck support can be included by extending the plaster. However, such support is seldom required, and consideration for surgery should be given in such cases.

A window is cut in the front for abdominal expansion. After the first cast, a radiograph is performed to confirm better correction of scoliosis. If satisfactory control is not obtained, casting can be tried once more with proper moulding of the cast only if the treating surgeon is confident that the curve is flexible and that the original cast was not applied properly. If the child feels uncomfortable, especially with regard to breathing, then the cast should be removed immediately.

The localizer cast must be changed every 3 months as the child grows in height and also as the plaster wears off and the cast loosens. It is not tolerated well by older children and hence is usually best suited to children younger than 5 years. Localizer casts can produce pressure sores, especially in children with underlying neurologic problems. Foreign objects that find their way into the cast can also cause pressure sores in normal children as well as in neurologically impaired children.

A 2012 study found that serial casting delayed surgery by an average of 39 months in moderate-to-severe early-onset scoliosis. ^[36]

A retrospective study reviewed 31 consecutive patients (average age, 25 mo) with a primary diagnosis of idiopathic infantile scoliosis who were treated with bracing, serial body casting, or VEPTR. ^[37] Of the 17 patients treated with a brace, nine had curve progression and went on to receive other treatments; the remaining eight showed an overall improvement of 51.2%.

The 10 patients who received body casts had a mean preoperative Cobb angle of 50.4º and an average correction of 59.0%. ^[37] The 10 patients who were treated with VEPTR had a mean preoperative Cobb angle of 90º and an average correction of 33.8%. The study results suggested that body casting is useful in cases of smaller, flexible spinal curves and that VEPTR is a viable alternative for larger curves.

A study by Iorio et al, which included 21 patients with an average Cobb angle of 48º (range, 24-72º) who underwent initial casting at an average age of 2.1 years (range, 0.7-5.4 y), found that potential determinants of the success of serial casting included (1) age of less than 1.8 years at the initiation of casting and (2) derotation of the spine to correct RVAD less than 20º. ^[38]

Preparation for surgery

The general condition of the child should be improved by providing appropriate nutrition and making sure the child is capable of undergoing general anesthesia. Any infections should be treated appropriately.

Flu prophylaxis is indicated for any child with lung problems. Pneumonia prophylaxis is required for any child on a ventilator.

Vertical expandable prosthetic titanium rib

VEPTR is is employed in the management of severe scoliosis in skeletally immature patients. (See the images below.)

VEPTR usually is indicated in patients with thoracic insufficiency syndrome (TIS). ^[39] Apart from having a spinal deformity, patients may have a deformity of the thoracic cage, such as fused ribs or a hypoplastic thorax. VEPTR helps rebuild the chest wall and correct the spinal deformity, thereby allowing the lungs to expand to achieve normal functioning. Several types of VEPTR devices are available, including the following:

• Cradle-to-cradle — Used in cases of fixed or missing ribs, severe scoliosis, and hypoplastic thorax
• Cradle-to-lumbar lamina hook — Used when scoliosis involves the lumbar region or when lower ribs are absent
• Cradle-to-S-hook — Attaches upper ribs to the pelvis and is useful in cases in which lower ribs are absent and lumbar bones are weak

The patient is placed in the lateral decubitus position. Two incisions are made: (1) a large J-shaped incision medial to the border of the scapula and curving anteriorly and (2) a small incision made distally so as to apply the distal end of the prosthesis to the spine. The prosthesis is applied over the rib cage and beneath the skin and muscle. After the proximal and distal ends are attached, the device is distracted with the aid of expansion pliers.

Intraoperative spinal cord monitoring (somatosensory evoked potentials [SEPs]) has been found to be useful in these cases. If SEPs change intraoperatively, then decreasing the VEPTR expansion may resolve the issue. Spinal cord monitoring can decrease the incidence of neurologic complications following excessive surgical correction.

Pediatric Isola spine system

The Isola system (see the image below) consists of screws with washers that are applied from posterior to anterior, horizontal to the frontal plane of the vertebral body, and parallel to the apex of the curvature. Screws may be applied through the staples.

Closed-top end screws are placed first. A rod is then contoured along the curvature and is cut to size, so that it extends about 1 cm beyond the end screws. The rod is passed between the two end screws, and open-end screws with staples are then placed in the remaining intervening vertebrae, with the contoured rod serving as a guide for positioning the screws. Caps are placed on the intermediate screws, and the rod is rotated approximately 180° to obtain both a coronal correction and a sagittal correction. ^[40]

Further correction can be accomplished by opening the vertebral spaces with a Cobb elevator after tightening one of the intermediate screws. At this stage, further correction can also be accomplished by applying distraction between the screw connector bodies. The disk space that is created can now be filled completely with bone graft material. Vertebral screws are compressed centrally, starting from the top of the screw to the bottom, and then to the top of the next screw. The final compression is applied across the apical vertebrae.

Rods are inserted to prevent progression of the curve, and the rods are extended every 6 months to keep pace with the child's growth. Hooks are used as anchors on the upper part of the curve, and pedicle screws are used in the lower part of the curve. At the apex of the curve, the muscle is not dissected, so as to maintain the blood supply to the bone at the apex.

The surgical wounds must be protected with padding to prevent injury. The prosthesis must be expanded every 4-6 months as the child grows. Expansion requires that a small incision be made at the site of distraction. When the child stops growing, the device can be removed, and other definitive procedures (eg, rib spreading) may be necessary.

The risks associated with surgery under anesthesia include the following:

• Bleeding
• Pneumonia
• Wound complications (eg, poor healing, infection)
• Device-related problems, such as allergic reaction to metal, or bending, breaking, or loosening of the device
• Neurologic deficit due to stretching of the spinal cord from expansion

Crankshaft phenomenon is a complication following isolated posterior fusion surgeries, in which the unfused anterior vertebral bodies continue to grow and cause lordosis and scoliosis. Crankshaft phenomenon is seen when the spine is skeletally immature, and typically occurs during the two peak growth velocity periods (ie, between birth and the age of 5 years and between the ages of 10 and 15 years). ^[41]

Paralysis is the most feared complication of surgery for scoliosis. A survey conducted by the Scoliosis Research Society determined that the incidence of acute neurologic complications resulting from the treatment of scoliosis was 0.72%. ^[42] In infantile scoliosis, because neural axis involvement is significant, the risk of neurologic injury is greater if not recognized preoperatively.

Infection is a risk with all surgical procedures; antibiotic prophylaxis is essential.

Pseudoarthrosis is a failure of the spine to fuse and is more common in adults than in adolescents.

Decompensation occurs because of overcorrection of the spinal curve, in which the curvature of the spine loses its flexibility, causing the patient to lean to one side.

Flat-back syndrome is seen less often now because of technical improvements since the Harrington rod. In this condition, patients have decreased lumbar lordosis and need to hyperextend their hips to stand or need to adopt a flexed-hip-and-knee gait, leading to increased back fatigue.

There is a risk of low-back pain, especially after lower distal level fusion. This may result from unfused levels of the spine or degeneration of the fused spine.

Rod fractures may occur in 15% of cases. ^[43] The risk of such fractures is not associated with the preoperative magnitude of scoliosis or kyphosis. The risk factors for rod fractures incldue the following:

• Prior fracture
• Single rods
• Stainless steel rods
• Small-diameter rods
• Proximity to tandem connectors
• Short tandem connectors
• Preoperative ambulation

Repeat fractures are common, especially with single rods. Rod replacement, with larger-diameter rods if appropriate, may be preferable to attempting to connect the broken rods; fractures signal fatigue of the rod.

The complications associated with casting include an increase in peak inspiratory pressure, which can result in increased respiratory complications. ^[44] Subclavian thrombosis after casting has also been reported in the literature. ^[45]