CHAPTER 11
Idiopathic Scoliosis and Congenital Scoliosis
Overview
• Idiopathic scoliosis is common in children and adolescents and has a prevalence of 2% to 3% in teens and preteens.
• The etiology is not established; it is considered a multifactorial condition.
• Genetic factors are not clear in assessing the risk of developing idiopathic scoliosis.
— Approximately 11.1% of patients have a first-degree relative with idiopathic scoliosis.
— The frequency of idiopathic scoliosis in both monozygotic twins is 73% to 92% (but not 100%), compared with 36% to 63% in dizygotic twins.
• Nongenetic intrinsic factors may contribute to development of idiopathic scoliosis.
— Rapid vertebral growth and skeletal immaturity (as curve magnitude increases, vertebral wedging occurs), are factors
— Human verticality of posture plays a role.
• Female-male prevalence
— 1:1 for small curves of approximately 10 degrees
— 5:1 for curves between 10 and 20 degrees
— 10:1 for curves greater than 30 degrees
DIFFERENTIAL DIAGNOSIS
• The typical patient with idiopathic scoliosis is an adolescent girl between 10 and 16 years of age with a thoracic curve having an apex to the right. Any deviation from this typical pattern warrants evaluation for an occult treatable underlying cause.
• When to suspect non-idiopathic scoliosis
— Patients 10 years and younger have a higher incidence of non-idiopathic scoliosis than adolescent patients (early onset scoliosis [EOS]).
— Atypical curve pattern (eg, thoracic curves with an apex to the left have a higher incidence of underlying neurologic cause)
— Sacrum and pelvis included within the curve, resulting in pelvic obliquity
— Associated kyphosis (may suggest a non-idiopathic cause, such as neurofibromatosis)
— Significant pain (idiopathic scoliosis is typically not painful)
— Coexisting medical condition with a known association with scoliosis (eg, neurofibromatosis, connective tissue disorders, congenital heart disease)
• Functional (nonstructural) scoliosis
— Most commonly caused by limb-length discrepancy or muscle spasm (eg, because of herniated intervertebral disk, spondylolysis/spondylolisthesis, diskitis, tumor) or deconditioning (lack of fitness)
— Functional curves are mild without any bony abnormalities.
— Symptoms of underlying condition are present.
— Curve corrects when the underlying problem is resolved.
DIAGNOSTIC CONSIDERATIONS
• Diagnosis is determined based on history, physical examination, and radiographs (thoracolumbar [TL] spine, anteroposterior, and lateral views).
• Physical examination
— With the patient standing, inspect the shoulders, scapulae, ribs, and waist for asymmetry.
— Palpate the top of the iliac crest, comparing height of right to left. If this reveals a limb-length discrepancy (which may cause nonstructural scoliosis), the hips and pelvis are made level by placing blocks (or office magazines) under the shorter limb. Once the pelvis is level, inspect the shoulders, scapulae, ribs, and waist for asymmetry (Figure 11-1).
• Perform the Adams forward bend test (Figure 11-2) by asking the patient to bend forward at the waist with knees straight and palms together. Scoliosis is associated with vertebral rotation. Vertebral rotation creates paraspinous asymmetry visible on the forward bend test. Axial rotation should be measured and documented with the use of a scoliometer.
Figure 11-1. The first step in the physical examination of a patient with suspected scoliosis is inspection of the back. In this patient, the pelvis is level but the right hip appears elevated because of the waist asymmetry caused by scoliosis. The right scapula is more prominent than the left, and the right shoulder is slightly elevated compared with the left.
Figure 11-2. Next, have the patient perform the Adams forward bend test. Vertebral rotation associated with scoliosis results in paraspinous rib prominence on the right.
Figure 11-3. The standard method for measuring scoliosis curve magnitude is referred to as the Cobb technique. Lines are drawn along the end plates of the most tilted vertebrae (a). In a patient with a mild curvature, the end plate lines are almost parallel and do not intersect on the radiographic film, so a second pair of lines (b) are drawn perpendicular to the end plate lines. The angle created by the intersection of perpendicular lines (b) is the curve magnitude (c).
• If asymmetry is present on the Adams forward bend test and/or the scoliometer measurement is over 6 to 7 degrees, TL standing anteroposterior and lateral radiographs should be obtained to evaluate and quantify the apparent scoliosis.
• The Cobb technique documents curve magnitude (Figure 11-3). Curves measuring 10 degrees or less are normal, considered spinal asymmetry, and should not be labeled as scoliosis.
• All patients with evidence of scoliosis should undergo a brief neurologic examination consisting of strength testing and deep tendon reflexes.
• Magnetic resonance imaging (MRI) of the spinal cord is indicated in the setting of atypical idiopathic curves (left, nonthoracic), rapidly progressing curves, EOS, and congenital scoliosis, as well as in the presence of neurologic signs of scoliosis.
Adolescent Idiopathic Scoliosis
INTRODUCTION/ETIOLOGY/EPIDEMIOLOGY
• Onset of adolescent idiopathic scoliosis may occur from 11 years of age until skeletal maturity.
• It is the most common type, representing approximately 89% of idiopathic scoliosis
• It is more common in girls, with curves greater than 30 degrees especially common in girls (10:1 female-male prevalence).
• Thoracic curves, apex to the right, are most common.
• Curves with apex to the left are more likely to have an underlying unrecognized neurologic cause.
• Primary risk factors for curve progression
— Female sex
— Skeletal immaturity
— Large curve magnitude at presentation
— Positive family history
• The relationship between patient age, curve magnitude, and the likelihood of curve progression has been demonstrated (Table 11-1).
SIGNS AND SYMPTOMS
• Shoulder, waistline, or trunk asymmetry may be noted by the patient or parent.
• Initial diagnosis is often determined during an annual physical examination (Box 11-1).
• Skeletally immature patients are asymptomatic, even when scoliosis is severe.
TREATMENT
• There appears to be increasing intolerance of the cosmetic deformity associated with scoliosis.
• The goal of the treating physician is to identify those patients at risk of curve progression and in those patients do as little as possible but as much as necessary to alter the natural history and prevent the undesirable consequence of untreated disease.
Table 11-1. Probability of Curve Progression: The Relationship Between Curve Magnitude and Age
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