Congenital Kyphosis

Congenital kyphosis is caused by vertebral anomalies. Anomalies are of three types

• Type I –  Congenital failure of vertebral body formation.
• Type II – Failure of vertebral body segmentation
• Type III- Combination of both of these conditions.

Type I is further has subtypes

• Posterolateral quadrant vertebrae
• Posterior hemivertebrae
• Butterfly (sagittal cleft) vertebrae
• Anterior or anterolateral wedged vertebrae

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

Progression is most rapid in type III kyphosis, followed by type I. 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.

Diagnosis of Congenital Kyphosis

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 sprut 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 for Congenital Kyphosis

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 – a posterior fusion is sufficient. This procedure halts growth of posterior physes while allowing continued growth of anterior physes  which may result in some degree of spontaneous reduction of the kyphosis during the growing years

• > 5 years, combined anterior and posterior fusion generally is required.

Type I Deformities

In children  with congenital kyphosis and age less than five years of age and deformity less than 50 degrees a posterior fusion is appropriate. Autogenous bone grafts are preferable but if sufficient graft is not present, allograft bone can be used.

The patient is placed in a corrective cast after the surgery, bed rest for 4 months, followed by ambulation in a Risser cast [an orthopedic device for encasing the entire trunk of the body, extending over the cervical area up to the chin].

If there is doubt about fusion solidity, the area is inspected surgically and further bone graft is added. The child may require casting for up to 12 months in such cases.

Type II, III Deformities

In younger children, posterior fusion extending from one vertebral segment above to one below the affected one would halt the progression.

In adolescents with mild-to-moderate thoracic deformities (< 50 degrees) can be tackled with posterior fusion and instrumentation. Rigid cast immobilization for at least 1 year is recommended.

Patients with severe kyphotic deformities require a combined anterior and posterior surgery. The surgeries in such cases include osteotomies and 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.