Causes of Congenital Scoliosis
The main causes of congenital scoliosis include:
Formation failure means that one or more bones of the spine (vertebrae) are incompletely formed during fetal development. These incompletely formed bones are abnormally shaped compared to completely formed vertebrae. These bones have the appearance of a triangle or wedge and, therefore, may cause the spine to tilt in the direction of the wedge. This is how they can cause a scoliotic curvature of the spine.
The presence of malformed bones does not necessarily result in a scoliotic curve. For example, two wedges on opposite sides of the spine may balance each other out. However, if both wedges are on the same side then the abnormal curve will be accentuated.
This is also referred to as separation failure. Segmentation/separation failure means that some of the bones of the spine (vertebrae) incompletely separate from one another during fetal development. This causes the bones of the spine to be abnormally connected (fused) to one another on one side of the spine. This connection (called a boney bar) causes the two sides of the spine to grow at different rates—slower than normal on the connected side—and results in an abnormal curvature of the spine.
Combination of Formation and Segmentation Failure
It is possible for both wedged shaped bones (formation failure) and connected bones (segmentation failure) to be the cause of congenital scoliosis. This is referred to as a mixed deformity.
The above developmental defects of the spine can range from mild to severe and they can affect one or multiple areas of the spine. The degree to which these occur will determine the severity of the scoliotic curve, the symptoms, as well as the requirement for treatment.
Children with congenital scoliosis usually do not experience any pain.