Congenital Kyphosis

Congenital kyphosis is the presence of ky[hotic deformity or hump in the spine due to congenital vertebral anomalies.

Kyphosis is exaggerated forward spine bend and it is called congenital as it occurred prior to birth.

The vertebral defect which usually occur in the first six to eight weeks of embryonic life causes the spine to develop a sharp forward angulation as it grows.

Congenital kyphosis is the most common cause of spinal deformity in North America

Types of Congenital Kyphosis

The anomalies fall into three groups

• Type I –  Failure of vertebral body formation.
  • Posterolateral quadrant vertebrae
  • Posterior hemivertebrae
  • Butterfly (sagittal cleft) vertebrae
  • Anterior or anterolateral wedged vertebrae
• Type II – Failure of vertebral body segmentation

Combination of the two can exist but is quite rare.

Type I deformities are more common and occur more commonly in the thoracic spine and at the thoracolumbar junction.

Defects of the formation may involve only a single level, but multiple defects are possible. The failure of the formation can result in a range of deformities from kyphosis [anterior defect] to kyphoscoliosis [anterolateral defect with a posterior corner hemivertebra].

About one-fourth of the type I deformities have associated neurological deficits. Kyphoses in upper thoracic spine are more likely to be associated with neurological problems.

Natural Progression of  Congenital Kyphosis

Rate of progression is lesser in cases with failure of separation.

The more severe the anterior defects, the more progressive the deformity.

Kyphosis from the failure of formation is progressive and, if left untreated, can lead to paraplegia.

The paraplegia is often seen more common during the adolescent growth spurt when a rapid increase occurs in the untreated kyphosis.

Apart from this a minor trauma may result in a neurological deficit.

Paraplegia is more common with kyphosis in the upper thoracic area as here, the collateral circulation is poorest.

Diagnosis

The deformity may be detected before birth on a prenatal ultrasound examination or noted on clinical examination after birth. Mild deformities may remain unnoticed till growth spurt where a rapid growth makes them obvious.

Mostly a kyphotic deformity is at the thoracolumbar junction or in the lower thoracic spine. Physical examination should also include neurological examination in detail to look for any subtle sign of deficit and examination to look for associated anomalies.

Imaging 

High-quality, anteroposterior and lateral radiographs are the basic imaging studies and help to

• Differentiate failure of segmentation and f failure of formation defects
• Rigidity of the kyphosis and instability of the spine [Flexion, extension and lateral flexion views]

Computed tomography with three-dimensional reconstructions helps to identify the amount of vertebral body involvement and estimates the possible progression. Significant incidence intraspinal abnormalities in these patients warrant MRI studies. MRI can also help to identify compression caused by kyphosis.

Cardiac evaluation and renal ultrasonography should be done in these patients to look for visceral abnormalities.

Treatment of Congenital Kyphosis

Nonoperative treatment in these patients is ineffective.

The operative procedure depends on

• Type of deformity
• Severity of the deformity
• Age of the patient
• Presence or absence of neurological symptoms.

Every patient needs to be individualized in these patients. Following are general guidelines

• <5 years age,  < 5o degrees of curve
  • Posterior fusion
  • Halts the growth of posterior physes while allowing continued growth of anterior physes
  • May result in some degree of spontaneous reduction of the kyphosis during the growing years

• > 5 years or >50 degrees of curve
  • Combined anterior and posterior fusion

Complications

• Pseudarthrosis – Failure of fusion
• Progression of kyphosis
• Paralysis
• Low Back Pain

First two complications can be minimized by performing anterior and posterior fusions for deformities > 50 degrees.

Risk of paralysis can be lessened by not attempting for maximum correction at the time of instrumentation.