Scoliosis Research Society (SRS)
Scoliosis Research Society (SRS)
An International Organization Dedicated to the Education, Research and Treatment of Spinal Deformity
Our Mission is to Foster Optimal Care for All Patients with Spinal Deformities

Congenital Scoliosis

Complex congenital spine deformity.
Figure 1:
Complex congenital
spine deformity.
The term "congenital scoliosis" refers to a spinal deformity caused by vertebrae that are not properly formed. This occurs very early in development; in the first six weeks of embryonic formation. Congenital scoliosis does not seem to run in families. Genetic studies to date have not yielded much evidence that this condition can be inherited. Although congenital scoliosis is often discovered during the infant or toddler period, in some children it does not diagnosed until their adolescent years.

Pediatric spine surgeons describe congenital spinal anomalies based on which part of the vertebra is malformed or connected. Depending on the structure of the anomaly, the child may exhibit scoliosis (a curve to the right or left), kyphosis (round back), or lordosis (sway back). However, not all congenital anomalies fit neatly into these categories. There are often elements of more than one deformity, particularly scoliosis and kyphosis occurring together (Figure1).

Pediatric spine surgeons may refer to the spine anomaly as a "failure of segmentation." This means that one or more vertebrae are abnormally connected together on one side. This connection will slow growth on that side of the spine. Unopposed growth on one side with slowed growth on the other leads to a spinal deformity. "Failure of formation," the most common type of congenital problem, means that the normal shape of the vertebra is disrupted (Figure 2). "Failure of segmentation" means that the abnormal vertebrae did not separate properly. (Figure 3) On the x-ray these vertebra will look like triangles instead of rectangles. X-rays only show a two-dimensional representation of what is really a three-dimensional problem. The abnormally shaped vertebra may cause a wedge in the front, back, or either side, or a combination, tilting the spine at that level. Pediatric spine surgeons often use descriptive terminology to designate how much growth potential may be in the congenital anomaly. The term "fully segmented" indicates that there is a growth plate and a disk on both the top and bottom of the abnormal vertebra. "Semi-segmented hemi vertebrae" have a disk and growth plate either above or below. "Non-segmented hemi vertebrae" are fused to the vertebra above and below. Since non-segmented hemi vertebrae have no growth plates, the curves they cause are much less likely to progress than those due to semi-segmented hemi vertebrae, which are less likely to progress than a fully segmented hemi vertebra. A "block vertebra" means that there is a missing disk space. Block vertebrae essentially have no growth potential and therefore rarely cause a progressive deformity.

Defects of Formation
Figure 2: Defects of Formation
A: Misshapen vertebra causing scoliosis B: Misshapen vertebra fused to normal vertebra
C: Three misshapen vertebrae without scoliosis
D: Three fused vertebrae without scoliosis
E: Trapezoidal shaped vertebrae with scoliosis
(Courtesy John T. Killian, M.D.)
Defects of Segmentation
Figure 3: Defects of Segmentation
A: Block vertebrae without scoliosis
B: Multiple misshapen vertebrae fused on the opposite side with scoliosis
C: Misshapen vertebra, unilateral bar, abnormal discs with scoliosis
(Courtesy John T. Killian, M.D.)

In the thoracic (chest) part of the spine, congenital anomalies of the ribs often correspond with congenital anomalies of the vertebra. For example, an extra thoracic vertebra might attach to an extra rib. Vertebrae that are connected together may be associated with ribs that are connected together. The anomalies of the ribs and vertebrae are not always identical, but are often similar. A child with congenital spine anomalies often has more than one. This may be a congenital failure of formation on both the right and left sides of the spine or several grouped together or a mix of failure of formation and segmentation.

Three-dimension CT scan of the spine showing a hemi vertebra (partially formed vertebra) at T-12 and between L-2 and L-3 vertebrae
Figure 4: Three-dimension CT scan of the spine showing a hemi vertebra (partially
formed vertebra) at T-12 and between L-2 and L-3 vertebrae
After the history and physical examination, the next step in evaluating congenital scoliosis is obtaining x-rays. X-rays of the neck should be taken to look for abnormal vertebrae in this region. The three-dimensional structure of the congenital anomaly may be best visualized on a CT scan with reconstruction (this study is usually done as part of a preoperative planning) (Figure 4). An MRI is very valuable to characterize the congenital anomaly and to be certain that there are no associated anomalies of the spinal cord. In children younger than 3 months (before the vertebrae ossify and harden), an ultrasound examination can scan the spinal cord for abnormalities without the need for sedation. The evaluation of the congenital spine will also include an assessment of the kidneys and the heart Because the kidneys and heart are formed at the same time as the vertebrae, children with congenital scoliosis have a 25% chance of having an anomaly in the urologic system (kidneys, bladder) or a 10% chance in the cardiac system. The child's limbs should be examined for any musculoskeletal abnormalities, such as a clubfoot or malformed hand/arm.

When your child's congenital spine anomaly is first diagnosed, no one will know exactly how much the spine deformity will progress as the child grows. There are some clues, however. Anomalies in the thoracic spine tend to worsen with growth of the patient. Multiple fully-segmented hemi vertebrae on the same side of the spine also tend to progress with growth. A hemi vertebra opposite a set of fused vertebrae is the most likely combination to progress as the child grows. Because the most rapid period of spinal growth is in the first 5 years of life, and then at adolescence, these are the two times when the congenital curvature must be monitored most closely.