Sagittal plane deformities in pediatric patients

1

Describe how sagittal plane alignment of the cervical, thoracic, and lumbar spine changes from birth to adulthood.

The sagittal alignment of the spine is dynamic and changes with age. In newborns the spinal column possesses a single C-shaped sagittal curve. Cervical lordosis develops as an infant gains independent head control and lumbar lordosis develops with progression to standing and walking. Young children have positive sagittal balance as noted by the forward displacement of the C7 plumb line relative to the anterior-superior corner of the S1 vertebral body. As lumbar lordosis increases during growth, progressive posterior displacement of the C7 plumb line occurs. Additional interactions between spinal and sacropelvic sagittal parameters occur as the child matures toward an adult sagittal alignment profile. In the adult, cervical lordosis measured from the inferior endplate of C2 to inferior endplate of C7 ranges from 30° to 45° and adjusts to maintain the head over the sacrum in the sagittal plane. Thoracic kyphosis measured from T2 to T12 ranges from 20° to 45°. The thoracolumbar junction (T10–L2) is neutrally aligned in the sagittal plane in adults as compared with children who have a slightly kyphotic alignment in this region. Lumbar lordosis measured from the superior endplate of L1 to superior endplate of S1 ranges between 30° and 60°, with most of the curvature occurring between L4 vertebra and the sacrum. In a balanced spine, a line from the center of the C7 vertebral body passes anterior to the thoracic spine, through the center of the L1 vertebral body, posterior to the lumbar spine, through the lumbosacral disc, and between S2 and the femoral heads.

2

What are the causes of pediatric sagittal plane deformities?

A wide range of conditions are responsible for pediatric sagittal plane deformities ( Table 41.1 ).

3

What factors are used to classify the various types of thoracolumbar kyphotic deformities and guide surgical treatment?

Thoracolumbar kyphotic deformities have been classified by Rajasekaran et al. ( ) based on the structural integrity of the anterior and posterior spinal columns.

• Type I kyphosis is present when both the anterior and posterior spinal columns are intact. Type I kyphosis may present with mobile disc spaces (type IA) as seen in Scheuermann kyphosis or with fused disc spaces (type IB) as seen in ankylosing spondylitis.

• Type II kyphosis arises due to deficiency of either the anterior (type IIA) or posterior (type IIB) columns. Type IIA kyphosis develops secondary to spinal pathologies such as tumors, infections, and traumatic fractures. Type IIB kyphosis develops due to spinal pathologies such as surgical laminectomy or congenital deformities such as myelomeningocele.

• Type III kyphosis is associated with deficiency of both columns and is stratified according to severity as ≤60º (type IIIA), >60º (type IIIB), or severe kyphosis associated with buckling collapse of the spinal column (type IIIC). Etiologies associated with type III kyphosis include congenital anomalies, trauma, neurofibromatosis, and prior spine surgery.

The kyphosis type may be used to guide selection among various surgical osteotomies for treatment of kyphotic deformities, including Ponte osteotomy, pedicle subtraction osteotomy, disc bone osteotomy, single-level vertebrectomy, and multiple-level vertebrectomy.

4

What is the deformity angular ratio?

The deformity angular ratio (DAR) is defined as the curve magnitude divided by the number of involved vertebral segments. (2) Patients with a longer, more gradual curve have a lower DAR. Sharp angular deformities, either in the coronal or sagittal plane, are associated with a higher DAR, and are generally more rigid deformities and are often accompanied by neural compression.

5

What is postural kyphosis?

Postural kyphosis is common in adolescence and arises due to slouching or poor posture. The deformity may be corrected by voluntary contraction of back musculature or by lying supine. Patients often report mild backache. Lateral radiographs often show a mildly increased thoracic kyphosis (<60°) without any pathologic vertebral changes such as focal wedging or endplate changes as seen in Scheuermann disease. Treatment consists of reassurance and education of the patient and family as the condition is a cosmetic concern and does not result in long-term problems. Physical therapy for postural and core-strengthening exercises is a treatment option.

6

What is scheuermann kyphosis and how is this condition diagnosed?

Scheuermann disease is the most common cause of structural thoracic or thoracolumbar hyperkyphosis in adolescents. Onset occurs during the prepubertal growth spurt in 0.4%–10% of adolescents, with males and females affected at similar rates. Although Scheuermann disease was originally attributed to abnormal development of the vertebral ring apophysis, true etiology remains unknown and proposed causes include disordered vertebral endplate endochondral ossification, endocrine abnormalities, genetic factors, and juvenile osteoporosis.

Patients present with thoracic or thoracolumbar deformity and/or back pain. Forward bending will increase kyphotic deformity and patients will be unable to correct the deformity with active trunk extension. A compensatory increase in cervical and lumbar lordosis is common. Patients often have tight hamstrings. Approximately one-third of patients have mild scoliosis in addition to increased kyphosis. The incidence of spondylolysis is also increased in this population.

Radiographic evaluation includes full-length standing posteroanterior (PA) and lateral images and a lateral hyperextension radiograph performed over a radiolucent bolster to assess kyphosis flexibility. On lateral radiographs, characteristic imaging features of Scheuermann disease include: thoracic kyphosis >45º, thoracolumbar kyphosis >30º, anterior wedging of three or more adjacent thoracic vertebrae >5º, vertebral endplate irregularities, Schmorl nodes, and disc space narrowing. The most common deformity pattern (type 1, typical pattern) involves the mid-thoracic region (T7–T9 apex) and is associated with multilevel vertebral wedging. Less commonly, the apex of the kyphotic deformity is located at the thoracolumbar junction (type 2, atypical pattern) and may involve the lumbar spinal region. The term lumbar Scheuermann disease is used to refer to a pattern of involvement limited to the lumbar spine and associated with endplate irregularities, Schmorl nodes, disc space narrowing, and wedging limited to one or two vertebrae. Magnetic resonance imaging (MRI) is not routinely obtained in the absence of neurologic symptoms, or rapidly progressive kyphosis, unless surgical correction of kyphosis is planned ( Fig. 41.1 ).

7

What are the nonsurgical treatment options for scheuermann kyphosis?

Nonsurgical treatment options include observation, physical therapy, and orthotic treatment. Physical therapy consists of postural, core-strengthening, and hamstring stretching exercises directed toward improving posture and flexibility, and decreasing pain. Brace treatment is considered for patients who are skeletally immature with at least 1 year of growth remaining and a kyphotic deformity <70º, but is poorly tolerated by patients. A deformity with an apex at T9 or above is traditionally treated with a Milwaukee type brace (cervicothoracolumbosacral orthosis [CTLSO]). A thoracolumbar orthosis (TLSO) is considered if the apex is below T9. A period of cast treatment prior to brace treatment may be considered for patients with rigid deformities that show limited passive correction on hyperextension lateral radiographs performed over a bolster.

8

When is surgical treatment indicated for treatment of scheuermann kyphosis?

Surgical treatment is considered for thoracic kyphotic deformities >70º–75º, thoracolumbar kyphotic deformities >55º, and for treatment of neurologic deficits due to disc herniation or cord compression. Additional indications for surgery include kyphosis progression despite brace treatment, painful deformities, and deformities associated with an unacceptable cosmetic appearance.