James W. Ogilvie

Goals of Surgical Treatment

Removal of the segmented hemivertebra and its superior and inferior discs, improvement of the deformity through compression internal fixation, and arthrodesis to the adjacent vertebrae are the goals of this procedure.

Diagnosis

Congenital malformation of the spinal elements is frequently made on routine neonatal roentgenograms. Thoracic asymmetry with forward bending or other signs of spinal deformity can lead to the diagnosis in early childhood. When the diagnosis is suspected, in addition to a general and specific neurologic examination of the lower extremities, standing 2 m x-rays of the entire spine in the posteroanterior and lateral projections should be made. Magnetic resonance imaging (MRI) of the spine with coronal images of the area under consideration will both rule out other neuraxis abnormalities and clearly define the vertebral anomaly. Thin-section computed tomography (CT) scans may be helpful, but the sagittal reconstructions can be misleading by implying a congenital bar or other failure of segmentation that is not actually present.

Indications for Surgery

There are two general indications for resection of congenital hemivertebra:

1. If there is a fully segmented hemi-element that has a viable growth plate on each side, progression of the scoliosis should be anticipated. Scoliosis progression can be 5 to 10 degrees per year or more, particularly if there is a contralateral unsegmented bar.

2. If the hemivertebra has already caused an unacceptable deformity, excision of the element and correction of the deformity is the only definitive treatment.

Timing of the surgery is variable. If there is a clear diagnosis and documented progression of the deformity, surgery should not be delayed unless other medical factors intervene.

Contraindications

1. Congenital scoliosis is often accompanied by other malformations of the cardiorespiratory and gastrointestinal systems. Right heart failure, poor nutrition, or other systemic factors precluding surgery should be considered.

2. Excision of an isolated wedge or congenital hemivertebra can usually achieve a maximum correction of 25 to 30 degrees. When more correction than this is needed, a multiple-level staged anterior vertebrectomy followed by posterior fusion is usually required.

Advantages

1. Excision of the hemivertebra and compression instrumentation is definitive treatment for this disorder.

2. The use of compression internal fixation allows removal of the postoperative orthosis under controlled conditions rather than depending on a cast for correction of the scoliosis.

3. There is no distraction applied to achieve the correction, thereby adding an additional element of safety when compared to lengthening procedures.

4. Decreasing the congenital scoliosis lessens the likelihood that secondary curves will require treatment.

5. Selectively limiting the fusion to adjacent vertebrae preserves as much axial growth as possible. In theory, excising a hemivertebra and fusion is the final treatment that is needed for congenital scoliosis.

Disadvantages

1. Thoracic hemivertebrectomy is a more difficult technically than in situ posterior fusion or anteroposterior hemiepiphysiodesis for congenital scoliosis.

2. When there is a mild, but progressive curve due to congenital hemivertebra, that is, < 25 degrees, the other two fusion options are usually appropriate.

Procedure: Left T11 Anteroposterior Hemivertebrectomy with Sublaminar Fixation

The patient is placed in the right lateral decubitus position with the thoracolumbar junction centered over the hinge in the operating table. Moderate flexion is created in the table after securing the patient to the table.