Study Guide

Congenital Scoliosis

Key Points:

Congenital scoliosis results from failure of formation or segmentation in vertebral development
Congenital scoliosis is associated with intraspinal abnormalities, musculoskeletal, cardiac, and genitourinary malformations
Curve progression and final severity of the deformity are related to the type and location of vertebral anomalies and remaining growth
Treatment goals include prevention of progressive deformity and preservation of thoracic growth and pulmonary function

Description:

Congenital scoliosis results from the failure of vertebral segmentation and/or formation during development resulting in curvature of the spine. The failure of normal vertebral development occurs around the 4th-6th week of gestation during the period of spine embryological development. (Pahys, 2018; Richards, 2014) Congenital scoliosis is classified based on the tendency of the curve to worsen or progress as non-progressive, mildly progressive, or highly progressive. (Hedequist, 2004)

Epidemiology:

Congenital scoliosis is estimated to occur in about 1 in every 1000 live births. (Pahys, 2018) About 10% of scoliosis deformities are due to congenital scoliosis. (Mackel, 2018)

Clinical Findings:

Careful attention should be made during the physical exam to look for other abnormalities or spinal dysraphism, such as leg or foot asymmetry, foot deformities, craniofacial malformation, or web neck. The skin should be evaluated for any areas of abnormal pigmentation, hairy patches, or skin tags over the spine. A complete neurological examination should be performed. A visual inspection of the trunk should include particular attention to any rib cage abnormalities and the patient’s inspiratory capacity. Spinal balance in relation to the pelvis should be assessed, including head tilt, shoulder inequality, and pelvic balance. Height should be measured at every visit to determine growth velocity. (Hedequist, 2007; Mackel, 2018)

Embryologic spine development occurs at the same time as the genitourinary, musculoskeletal, and cardiovascular systems. Thus, patients with congenital scoliosis often have associated abnormalities in these organ systems and should be evaluated for cardiac or genitourinary malformations. (Hedequist, 2004)

Imaging Studies:

Diagnosis of congenital scoliosis in infant is often made on plain radiograph. Standing PA and lateral spine x-rays and cervical spine x-rays should be performed if able at diagnosis and during follow-up. Bending x-rays are helpful to evaluate for flexibility of the curves. Individual vertebral anomalies, pattern and laterality of involvement, and associated rib abnormalities or fusions should be documented. The magnitude of the curve is assessed by the Cobb angle, which is the angle formed between the superior endplate of the most tilted upper vertebra and the inferior endplate of the most tilted lower vertebra. Typical landmarks may be difficult to discern given abnormal vertebral formation. Choosing consistent levels and comparing these on serial radiographs over time using the earliest radiograph as a baseline, can detect slow progression.

Computed tomography (CT) can be particularly helpful to assess the three-dimensional deformity seen in congenital scoliosis, as well as identify anomalies that are not easily visualized on plain radiographs. CT can also identify chest wall deformities and lung volume. (Hedequist, 2007; Mackel, 2018)

MRI of the complete spine is recommended as part of the initial diagnostic evaluation for all patients with congenital scoliosis even in the presence of normal neurologic examination to evaluate for spinal dysraphism, which can occur in about 30% of patients with congenital spine anomalies (Hedequist, 2007). MRI is also recommended for any patients with abnormal neurological exam findings or during preoperative evaluation. Patients have a high incidence (21-37%) of intraspinal anomaly such as tethered cord, diastematomyelia, syringomyelia, diplomyelia, Arnold-Chiari malformations, and intraspinal tumors, which would be visualized on MRI. (Richards, 2014)

To evaluate for associated conditions, patients with congenital scoliosis should undergo a renal ultrasound and echocardiogram. (Hedequist, 2004)

Treatment:

The rate of curve progression and the severity of the curve at final growth are dependent on the type of vertebral anomaly, the location of the vertebral anomaly, and the growth remaining at the time of diagnosis. The most rapid rates of growth occur in the first five years of life and during the adolescent growth spurt. (Hedequist, 2007) Disc spaces visualized on radiographs, suggestive of the presence of vertebral growth plates, can predict the rate of progression of deformity. (Richards, 2014) Combined deformities, such as when a unilateral bar is seen with a contralateral hemivertebra, are especially rapidly progressing. (Richards, 2014)

Treatment decisions are based on the size of the curve, the nature of the deformity, and the expected progression. Semisegmented or incarcerated hemivertebra and block vertebra rarely require treatment due to their slow progression. More severe deformities, however, can progress rapidly, and if left untreated can exceed 40 degrees by 10 years of age. (Mackel, 2018) Therefore, the goal of treatment in congenital scoliosis is early detection and treatment prior to the development of a severe curve. (Richards, 2014)

Bracing is generally not effective in preventing progression of congenital scoliosis, but may have a limited role in slowing progression of a flexible compensatory curve to allow time for growth prior to surgical intervention. (Richards, 2014)

Indications for surgical intervention include curves >40 degrees, curves with steady progression, or curves due to unilateral unsegmented bar with or without contralateral hemivertebra.

Hemiepiphysiodesis
Mild curves with an anticipated progressive deformity can be treated with anterior and posterior hemiepiphysiodesis on the convex side of the curve. This procedure is most often indicated for patients with fully segmented hemivertebra without deformity. This procedure typically does not correct curves but is intended to halt the progression of the curve. (Hedequist, 2004; Hedequist, 2007)

In situ instrumentation and fusion
Indicated in patients with curve less than 50 degrees that are short segment and who have significant growth remaining. This includes patients with fully segmented hemivertebra without deformity or patients with unilateral bar with or without a contralateral hemivertebra when diagnosed before progression to severe curve. If the potential for anterior growth remains, these patients will also require an anterior procedure to prevent the crankshaft phenomenon. (Hedequist, 2004; Hedequist, 2007)

Hemivertebra Excision
Excision of hemivertebra can be particularly useful in children younger than 5 years of age with a fully segmented hemivertebra located in thoracolumbar, lumbar or lumbosacral spine. Ideally, this is performed while the child is young enough that he or she can tolerate a cast and before rigid compensatory curves develop. Therefore, the indications for this procedure are younger than 5 years old with single hemivertebra that leads to curve greater than 40 degrees. (Hedequist, 2004)

Growing Rods
Recommended in patients with long segment curves who are under the age of 5 years. This is useful in order to minimize the negative effects that arthrodesis has on growth. (Karol, 2019) Magnetic rods limit the necessity of multiple invasive procedures.

Vertical Expandable Prosthetic Titanium Rib (VEPTR)
Very severe curves may require osteotomy or thoracoplasty to achieve curve correction, especially if the patient has a congenital rib fusion. Similar to growing rods, the VEPTR can be expanded at regular intervals (often every 6 months) to allow for growth. These are useful for expanding thorax volume to prevent thoracic insufficiency syndrome. Therefore, the VEPTR is indicated in patients with congenital rib fusion and resultant constricted hemithorax. (Hedequist, 2007)

Complications:

Severe congenital scoliosis with associated rib deformities can result in thoracic insufficiency syndrome due to reduced thoracic volume and function if not addressed at a young age. (Karol, 2019)

Any surgical treatment of congenital scoliosis needs neuromonitoring due to the high risk of neurologic injury in this patient population (Hedequist, 2017; Richards, 2014). Complication rates in surgical treatment of early onset scoliosis, including congenital scoliosis are high and include risk of infection, loss of fixation, unintentional fusion, and progressive kyphosis. (Karol, 2019)

Patients who undergo fusion procedures are at risk of the crankshaft phenomenon, which is a rotational and angular deformity that results from continued growth of anterior elements in the spine after posterior spinal fusion. (Murphy, 2017) Younger patients (Risser 0), are at highest risk of developing this phenomenon. (Pahys, 2018)

References:

Hedequist DJ, Emans J: Congenital scoliosis. J Am Acad Orthop Surg, 2004;12:266-275.
Hedequist DJ, Emans J: Congenital scoliosis: a review and update. J Pediatr Orthop, 2007;27:106-116.
Hedequist DJ. Surgical treatment of congenital scoliosis. Orthop Clin North Am, 2007;38:497-509.

Hensinger RN: Congenital scoliosis: etiology and associations. Spine (Phila Pa 1976) 2009;34:1745-1750.

Karol LA. The natural history of early-onset scoliosis. J Pediatr Orthop, 2019;39:S38-S43.

Mackel CE et al. A comprehensive review of the diagnosis and management of congenital scoliosis. Childs Nerv Syst, 2018;34(11):2155-2171.

Murphy RF, Mooney JF. The crankshaft phenomenon. J Am Acad Orthop Surg, 2017;25:e185-e193.

Pahys JM, Guille JT. What’s new in congenital scoliosis? J Pediatr Orthop, 2018;38(2):172-179.

Richards BS, Sucato DJ, Johnston CE. Scoliosis. In: Herring JA. Tachdjian’s Pediatric Orthopaedics. 5th ed. Philadelphia, PA. Elsevier; 2014:483-579.