Scoliosis (Fig. 152.1) is a structural or postural deformity of the spine that results in a lateral (coronal) deviation or curve. Scoliosis is associated with rotation of the vertebral bodies located within the curve. It may also be associated with an arm or leg length difference, particularly in cases of idiopathic or congenital scoliosis.

Scoliosis is most commonly idiopathic, degenerative, or a result of vertebral anomalies. Less prevalent is scoliosis consequent to disease-related or iatrogenic causes. Growth asymmetry at the vertebral end plate, rib, and pelvic growth centers can result in scoliosis and progression of a scoliotic curve [1,2].

Scoliosis affects between 3% and 30% of the population; about 0.25% require treatment [3]. The incidence of scoliosis increases with age [4] (Table 152.1). The scoliotic curve may be congenital; appear during infancy (infantile scoliosis); or develop in childhood (juvenile scoliosis), adolescence (adolescent scoliosis), or adulthood. When the diagnosis of scoliosis is made in an adult patient, the curve is identified as either adult onset (degenerative) or adult presenting (a previously undiagnosed idiopathic adolescent curve).

There is increasing evidence that idiopathic curves can result from genetic or epigenetic factors. Gene candidates have been identified in a genome-wide association study. Statistical associations with scoliosis exist for gene polymorphisms (interleukin receptor and vitamin D receptor genes; ATRX gene; and chromosomes 6, 9, 16, and 17) [5–8]. All are associated with idiopathic curves. Epigenetic factors that might contribute to the development of scoliosis relate to maternal age, spinal cord injury before the age of 5 years (96% prevalence of scoliosis), DNA methylation, and transient fetal hypoxia [9–12]. These are only associations, and at this time any causality or mechanism of action is unclear.

Other types of scoliotic curves can begin with degenerative changes in the spine, congenital malformation of the vertebrae (usually incomplete fusion—butterfly vertebrae or hemivertebrae), tumor, neuromuscular or connective tissue disease, trauma, surgery, or radiation therapy.

Kyphosis

Thoracic kyphosis is an excessive sagittal deviation in thoracic spine alignment, a dorsal apex curve exceeding 40 degrees. Possible causes include osteoporotic compression fractures (note that most of these fractures are asymptomatic and unidentified), direct trauma, chronic kyphotic posture, tumor, radiation therapy [13], and Scheuermann disease. A resulting wedge deformity of the vertebral bodies produces the malalignment. Animal studies suggest that gestational and neonatal hypovitaminosis D or alterations in calcium and phosphorus concentrations in neonatal feedings can play a role in the development of pathologic kyphosis. The incidence of kyphosis in animals studied with maternal vitamin D deficiency during gestation or with low calcium and phosphorus feed content was 32%. No similar humans studies have been published. Earlier presentation of the kyphotic deformity was seen in cases of maternal hypovitaminosis D [14].

Cervical kyphosis is pathologic. Infection (particularly tuberculosis), tumor, abnormal development of the cervical vertebrae, trauma, and advanced degenerative disease of the spine can produce cervical kyphosis. Kyphosis related to trauma (including laminectomy) or advanced degenerative changes in the cervical spine (due to disease such as rheumatoid arthritis or the mechanical changes that can occur over time) becomes more prevalent with advancing age. The most common tumors are manifested early in life as osseous or neural extramedullary masses. They include (in order of decreasing frequency) chordoma, bone cyst, Ewing sarcoma, meningioma, schwannoma, and neurofibroma [15]. As a feature of the congenital cervical vertebral dysmorphic syndromes, cervical kyphosis is noted in the following syndromes: Down, Morquio, Goldenhar, Klippel-Feil, Stickler, Williams, and Larsen [16].

Scoliosis is usually asymptomatic. If symptoms are present, they generally are produced by scoliosis as it directly relates to the location and severity of the curve. Large or highly rotated curves can produce pain and have the potential to produce symptoms related to the cardiopulmonary or nervous systems. Curves that exceed 60 to 80 degrees begin to affect other organ systems. They can produce shortness of breath or poor endurance due to decreased lung capacity. If there is pressure on nerve roots or the spinal cord, the patient may experience paresthesia or hypesthesia, weakness, and bowel or bladder involvement.

There is some controversy as to whether cosmetic changes related to thoracic scoliosis contribute to low self-esteem, anxiety, and depression (particularly in adolescents). Quality of life indices do not differ for adults by the age of 30 years [17].

Musculoskeletal pain may occur in performing activities of daily living that require a full active range of shoulder motion, such as overhead or extended reach activities. There may be upper back and neck pain in lifting or carrying because of strain of the scapular or shoulder muscles.

Kyphosis

Thoracic kyphosis is usually asymptomatic. If symptoms do appear, they are commonly associated with intermittent aching back pain and stiffness that are most prominent at the apex of the curve. Compensatory lumbar lordosis can be associated with low back pain.

Kyphosis with a wide scapular spread and shoulder and head protraction restricts both shoulder range of motion and the ability to look upward. When the ability to compensate for this with cervical or lumbar motion is compromised, kyphosis results in difficulty in performing overhead activities. Patients with cervical kyphosis may also complain of neck pain and the inability to look upward.

Scoliosis is usually apparent on inspection, although small thoracic curves with minimal rotation or a small lumbar curve can be difficult to detect. Have the patient bend forward (Adam forward bend test). If pelvic and lower extremity asymmetries affect the appearance of the back, minimize these by examining the patient in a seated position. Vertebral body or rib rotation associated with scoliosis is most readily seen when the patient bends forward. The tilt of the back, reflective of the angle of rotation, can be quantified by the use of a type of level, the scoliometer. The level is placed on the forward bent back in the area of maximum tilt and measures that angle. In idiopathic thoracic scoliosis, an angle of 7 degrees roughly corresponds to a scoliotic curve between 10 and 20 degrees.

Scoliosis can produce apparent asymmetry of breast size, asymmetry of the waist fold contour, asymmetric appearance of arm or leg length, or unequal iliac crest and shoulder height. A true leg length discrepancy exceeding 2.2 cm is indicative of asymmetric growth and possible scoliosis [18].