38: Hemivertebrae Resection

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Procedure 38 Hemivertebrae Resection

Rani Nasser, Matías G. Petracchi, Oheneba Boachie-Adjei, John K. Ratliff

Indications

image The primary objective in surgical treatment of hemivertebrae is to prevent the progression to severe spinal deformity.

image Ideal surgical candidates should have their deformity addressed before the development of compensatory curves.

• Progressive curve greater than 40 degrees
• Pelvic obliquity with deviation generating spinal imbalance

image Single, fully segmented hemivertebrae located at the thoracolumbar junction can deteriorate at a rate of 2 to 3.5 degrees per year.

image Hemivertebrae may lead to a rapidly progressing torsional deformity.

• Anatomic convex compression can transform into a concave mechanical compression.

Indications Pitfalls

• During the adolescent growth spurt, patients with congenital kyphoscoliosis may incur a rapid deterioration because of compression of the spinal cord.

• Adolescent growth spurt occurs at a mean age of 13.7 years.

• Hemivertebrae located higher up in the spine (cervical or thoracic) have a higher risk of intraspinal abnormalities.

Examination/Imaging

image History and physical (Figure 38-1)

image Routine history and physical with special attention to progression of deformity

• Hemivertebrae deformities do not follow any clear genetic inheritance patterns.
• Consider anomalies associated with the spectrum of spine deformity.
♦ VACTERL syndrome: vertebral anomalies, anal atresia, cardiovascular anomalies, tracheoesophageal fistula, esophageal atresia, renal and/or radial anomalies, and/or limb defects (1 in 10,000-40,000 live births)
♦ Genitourinary tract anomalies (26%)
♦ Cardiac defects (26%)

image Imaging

• Radiographs
♦ Anteroposterior (AP) (Figure 38-2, A and C) and (Figure 38-2, B) lateral
♦ Dynamic bending and traction films
• Computer tomography
♦ Coronal, sagittal, and three-dimensional reconstructions
• Magnetic resonance imaging (sagittal, Figure 38-3, A; and coronal, Figure 38-3, B)
♦ Evaluate for possible associated cord abnormalities.

• Arnold-Chiari malformation, syringomyelia, diastematomyelia, diplomyelia, or a tethered cord

image

FIGURE 38-1

image image image

FIGURE 38-2, A-C

image image

FIGURE 38-3, A-B

Treatment Options

• In situ posterior fusion

• The technique is not indicated in patients who are skeletally immature.
• Isolated posterior fusion is not preferred in young children, because of the reduced potential for correction.
• Thirty-six percent of young children by age 4 years could develop lordosis and bending of the fusion mass as the unfused anterior vertebral bodies continue to grow.
• Known as the crankshaft phenomenon
• Treatment goal is preventative and does not primarily address correction.

• Combined anterior and posterior fusion

• More substantial correction with diskectomies, combined anterior and posterior reconstruction of spinal deformity
• No crankshaft complications
• Decreased risk of pseudarthrosis
• May leave a residual curve, loss of growth potential in fused segments

• Epiphysiodesis

• Growth arrest on the convex side is indicated in patients with growth potential remaining only on the concave side.
• Concave growth is unpredictable and kyphosis may develop with growth of the posterior elements.
• Convex hemiepiphysiodesis performed across the entire measurable curve
• Optimized in patients less than 5 years old whose curve deformity has not progressed beyond 60 degrees.

• Hemivertebrae resection

• Eliminates potential for curve progression and potential to correct 60% to 70% of deformity
• Adjacent segments not involved and have no restriction on growth
• Decreases risk of pseudarthrosis and crankshaft phenomenon
• Could be performed as a combined anterior/posterior (single session or staged by 10 days) or posterior approach

Surgical Anatomy

image Expose the convex and anterior side of the hemivertebrae.

Positioning

image Lateral decubitus position

• Use lateral-posterior or simultaneous anterior/posterior approaches.
• Special attention should be paid to position the convex side up.

image Prone position

• For single posterior approaches or sequential anterior-posterior approaches
• Relton-Hall four-poster frame (or similar device)

Positioning Pearls

• Abdomen relieved of all pressure while prone

Positioning Equipment

• Relton-Hall four-poster frame for prone cases

Portals/Exposures

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