Infantile and Juvenile Scoliosis

Etiology

By definition, early-onset scoliosis occurs in children younger than 10 and encompasses a heterogeneous spectrum of causes. Causes include congenital, structural, neuromuscular, syndromic, and idiopathic scoliosis.[1][2] By convention, infantile scoliosis presents in children younger than 3, whereas juvenile scoliosis presents in children aged 3 to 10.

• Idiopathic scoliosis is defined as scoliosis with no known cause or association with another disease. 
• Congenital scoliosis results from abnormal vertebral formation or segmentation present at birth.
• Structural scoliosis results from a structural abnormality, such as fused ribs, a diaphragmatic hernia, or chest wall abnormalities.
• Neuromuscular scoliosis results from neuromuscular disorders such as cerebral palsy or muscular dystrophy.
• Syndromic scoliosis is often associated with vertebral anomalies, anal atresia, cardiac defects, tracheoesophageal fistula, renal abnormalities, and extremity defects (eg, VACTERL: vertebral anomalies, anal atresia, cardiac defects, tracheoesophageal fistula, esophageal atresia, renal anomalies, and limb abnormalities), neurofibromatosis, and other syndromes.

Epidemiology

Early-onset scoliosis, regardless of cause, accounts for approximately 10% of all pediatric scoliosis cases and is far less common than adolescent idiopathic scoliosis.

Pathophysiology

Early-onset scoliosis progresses when asymmetric spinal loading, vertebral growth modulation, and spinal rotation reinforce vertebral wedging during periods of rapid growth.[1] Thoracic deformity reduces rib cage volume and chest wall motion, thereby restricting ventilation and potentially impairing lung growth during early childhood.[3] Thoracic insufficiency syndrome refers to the inability of the thorax to support normal respiration or lung growth. Neuromuscular and syndromic early-onset scoliosis often progress because weak or poorly coordinated trunk muscles cannot counterbalance the effects of spinal growth and gravity.[4]

History and Physical

Patients may present with an obvious spinal deformity with or without a known syndromic condition. This spinal abnormality may represent the initial manifestation of a syndrome. Children may present with shoulder or pelvic asymmetry, rib prominence, truncal shift, chest wall asymmetry, abnormal posture, delayed motor milestones, respiratory symptoms, or a spinal curve detected during evaluation of a known syndrome.

A complete pediatric history, including the birth history, should be obtained. The history should document the age at onset, birth and developmental history, neurologic symptoms, pain, respiratory symptoms, feeding difficulties, family history, prior imaging, prior treatments, and syndrome-specific comorbidities. Additionally, clinicians should assess the functional effects of the deformity and any associated conditions.

The physical examination should include a comprehensive neurologic assessment and photographic documentation of the spinal deformity. Clinicians should assess and document standing balance, shoulder and pelvic height, trunk shift, rib prominence during the forward bend test, chest wall shape, leg length, skin markers of dysraphism, joint laxity, neurologic function, and curve flexibility. When possible, clinicians should also evaluate spinal flexibility with the child positioned on the examination table to determine the relative rigidity of the spinal column.

Physical Examination

The following are important elements of the physical examination:

Neurologic examination:

• Sensation
• Motor function
• Abdominal and deep tendon reflexes

Pulmonary function assessment:

• Forced vital capacity
• Forced expiratory volume in 1 second
• Total lung capacity
• Spirometry
• Thumb excursion test [4]

Assessment for spinal dysraphism:

• Chest dimpling
• Sinus tracts
• Scars [4]

Evaluation

Evaluation should define the etiology, residual growth, 3D deformity, progression rate, pulmonary reserve, neural axis risk, and medical readiness for conservative or surgical treatment. A thorough evaluation by an interdisciplinary team is mandatory. The evaluation should include a complete assessment of the patient’s overall medical and social status.[5][6]

Imaging

Radiography is the primary imaging modality for tracking deformity, measuring angular deformity, and assessing skeletal maturity. Hand radiography enables determination of the patient’s Sanders score, whereas pelvic radiography enables assessment of the triradiate cartilage and Risser stage. Both modalities help estimate the amount of remaining growth. Low-dose biplanar imaging can reduce cumulative radiation exposure and, when available, provide a 3D assessment.

• Spinal radiography:
  • Obtain standing posteroanterior and lateral images of the entire spine.
  • Obtain supine images for patients unable to stand, although the curve may appear less severe.
  • Measure the Cobb angle on the largest coronal curve.
  • Measure thoracic kyphosis on the lateral radiograph.
  • Categorize annual progression in degrees per year for classification and treatment planning.
• Rib vertebral angle difference:
  • Measure the rib vertebral angle difference.
  • A difference greater than 20° indicates an increased risk of scoliosis progression.

Computed tomography (CT) imaging has a substantial radiation burden and is not commonly obtained. This imaging modality provides detailed visualization of the bony vertebral anatomy and ribs. CT should be reserved for complex congenital bony anatomy, preoperative planning, or uncertain vertebral or rib morphology because the cumulative radiation exposure is substantial.

Magnetic resonance imaging (MRI) can identify abnormalities of the spinal cord. This modality can also detect associated conditions such as Chiari malformation, syrinx, or tethered cord. MRI should be obtained for neurologic abnormalities, pain, atypical curve patterns, rapid progression, congenital anomalies, suspected neural-axis pathology, and before operative treatment when the findings could alter treatment. MRI should always be obtained in patients younger than 10, although clinicians may consider postponing imaging in children younger than 3 without neurologic or radiologic abnormalities to avoid the anesthesia exposure required for this study.[7] 

Treatment / Management

General treatment and care aim to halt progression of the spinal deformity. Treatment also aims to increase thoracic volume, thereby improving pulmonary and cardiac function. Results from recent studies showed greater consensus than 15 years ago regarding conservative treatment for younger patients without large or rigid curves.[8](B3)

Conservative Options

Observation: 

• Observation may be considered for small, flexible curves because spontaneous resolution is possible; however, close surveillance is required.
• Therapeutic intervention is necessary if the curve subsequently progresses or if the angle is greater than 30° to 40° at presentation.[9]
(B3)

Spinal bracing:

• Provides a continuous corrective force
• Generally is more convenient than casting
  • Can be removed intermittently
  • Often applied without anesthesia support

Spinal casting:

• Achieves high clinical and radiographic success rates in infants and young children [9]
• Requires close monitoring to ensure that late progression does not occur during adolescence
• Requires multiple anesthetic events for cast application
(B3)

Before any intervention-based treatment, the patient’s health and functional status should be optimized.[10][11](B3)

Surgical Options

A surgical procedure is often indicated when conservative treatment does not control the deformity, the curve progresses rapidly, or the patient presents with a substantial curve. Definitive spinal fusion is typically not performed in those younger than 10 and is generally delayed until early adolescence, when minimal or no further spinal growth is expected.[12] Growth-friendly surgical procedures in skeletally immature children allow the construct to lengthen as the child grows.

• Traditional growing rods: These can be inserted with proximal and distal anchors, such as hooks or pedicle screws. The rod can be lengthened during a smaller surgical procedure performed at planned intervals. Although this technique is effective, associated risks include anchor pullout, repeated need for surgical procedures, and infection.[13][14]
• Magnetic growing rods: Magnetically controlled growing rods use a similar placement of proximal and distal anchors, such as hooks or pedicle screws. However, the rod is externally elongated by magnetic control. Patients generally need to be at least 2 years old and weigh at least 25 lb, and clinicians must consider the possible need for future MRI.
• Vertical, expandable prosthetic titanium rib-expansion thoracoplasty: Vertical expandable prosthetic titanium rib–expansion thoracoplasty may be used in patients with chest wall abnormalities. The procedure places instrumentation on the ribs using various possible anchor combinations to expand the thorax and reduce the spinal deformity. Complication rates are higher than those associated with traditional growing rods.
• Growth-guided techniques: Growth-guided techniques, including the Shilla procedure, involve placing pedicle screws in the rigid apical vertebrae, which represent the most severe portion of the deformity. More proximal and distal pedicle screws use a locking cap mechanism that allows longitudinal rod movement during growth, whereas fixed pedicle screws maintain spinal alignment. Because of the biomechanical forces, rod breakage is expected, and 4.5-mm rods generally last about 4 to 6 years.
• Hemivertebrectomy with short-segment fusion: Used to treat congenital scoliosis caused by a fully or partially segmented hemivertebra. The hemivertebra is removed, and the adjacent vertebrae are then fused and instrumented with rods and screws. This procedure does not provide gradual modulation of growth, although instrumentation without fusion can be considered for less severe curves.[9]
• Halo traction: Halo traction can be used as a preoperative or therapeutic technique for severe, stiff curves to improve spinal flexibility and reduce the risk of neurologic injury during surgery. A halo ring is fixed to the patient’s skull with pins and then connected to a traction setup. Traction is gradually increased over days to weeks to stretch the soft tissues, improve pulmonary function, and partially correct the curve.[15] 
(B2)

Differential Diagnosis

The differential diagnosis includes:

• Nonstructural scoliosis due to leg-length discrepancy or postural imbalance
• Painful scoliosis associated with:
  • Osteoid osteoma
  • Osteoblastoma
  • Aneurysmal bone cyst
  • Hemangioma
  • Infection
  • Inflammatory disease
  • Benign or malignant spinal tumors
  • Neural-axis abnormalities
  • Congenital vertebral anomalies
  • Neuromuscular disorders
  • Syndromic connective tissue or neurocutaneous disorders
• Pain, nocturnal pain, neurologic deficits, atypical curve direction, rapid progression, abnormal reflexes, cutaneous markers of dysraphism, or systemic symptoms
  • Should prompt MRI and targeted laboratory or specialty evaluation

Staging

Classification for nomenclature purposes was established by Williams et al in collaboration with the Children’s Spine Study Group and the Growing Spine Study Group. Results from studies demonstrated that this classification system has acceptable interobserver and intraobserver reliability.

The Classification of Early-Onset Scoliosis

1. Patient age

2. Etiology:

• Congenital or structural (C)
• Neuromuscular (M)
• Syndromic (S)
• Idiopathic (I)

3. Coronal Cobb angle: Measure the largest curve on standing posteroanterior radiography of the entire spine.

• Less than 20° (1)
• 20° to 50° (2)
• 51° to 90° (3)
• Greater than 90° (4)

4. Maximum kyphosis: Measure maximum kyphosis on lateral radiography of the entire spine.

• Less than 20° (-)
• 20° to 50° (N)
• Greater than 50° (+)

5. Progression modifier

• Less than 10° per year (P0)
• 10° to 20° per year (P1)
• Greater than 20° per year (P2)

Example: A 7-year-old patient with congenital scoliosis who presents for a 1-year follow-up with a 23° coronal curve, 57° of kyphosis, and annual progression of 15° would be classified as 7C2+P1.

Prognosis

Early-onset scoliosis comprises a heterogeneous group of diseases. Prognosis is largely linked to comorbidities and deformity at the time of presentation. Prognostic factors include the underlying syndrome and, more importantly, the curve's effect on thoracic growth and function.

Lung development is substantial during the first 2 years of life, and alveolar maturation is nearly complete by 8 years of age. Patients with thoracic restriction caused by scoliosis may develop alveolar hypoplasia, abnormal ventilation, and decreased lung compliance. Cardiac complications, such as cor pulmonale and pulmonary hypertension, may also occur. This inability of the thoracic cage to appropriately accommodate lung growth and function is known as thoracic insufficiency syndrome.

The prognosis of the deformity is closely related to the patient’s skeletal maturity and degree of deformity. The distance from the thoracic spine to the sacrum increases by approximately 2 cm per year during the first 5 years of life, by 1 cm per year from ages 5 to 10, and by 1.8 cm per year thereafter until maturity. Rapid growth occurs during the first 5 years of life and again during adolescence. The rib-vertebral angle difference at the apical vertebra is a prognostic indicator of progression in idiopathic early-onset scoliosis. A rib-vertebral angle difference greater than 20° at initial presentation is more likely to be associated with progression.

Complications

Patients older than 40 with untreated early-onset scoliosis have a 50% higher mortality rate. Furthermore, a curve greater than 70° is associated with increased mortality. Untreated progressive early-onset scoliosis can lead to thoracic insufficiency, restrictive lung disease, pulmonary hypertension, cor pulmonale, functional impairment, and increased mortality among patients with severe curves or medically complex underlying conditions.

Casting and bracing complications include skin injury, pressure areas, feeding intolerance, hygiene challenges, adherence burden, and transient respiratory compromise during cast application. Complications of growth-friendly surgical procedures include infection, anchor failure, rod fracture, failure to lengthen, proximal junctional kyphosis, autofusion, neurologic injury, repeated anesthesia exposure, and unplanned return to the operating room. Early definitive thoracic fusion can restrict thoracic growth and is associated with lower forced vital capacity, especially after extensive proximal thoracic fusion. Prevention of surgical site infections should follow best-practice measures for high-risk pediatric spinal surgical procedures, including preoperative risk optimization, perioperative antibiotic planning, skin preparation, and standardized postoperative wound surveillance.