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 – often before the mother even knows she is pregnant. The cause is unknown. Congenital scoliosis does not run in families. Although it is often discovered during the infant or toddler period, some curves may not be diagnosed until the adolescent years. The curves tend to progress only while the child grows, unless adjacent (compensatory) curves become significant in size.
Spinal deformity 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.
Scoliosis surgeons may refer to the spine anomaly as either “failure of formation” or “failure of segmentation.” “Failure of formation” means one or more vertebrae became partially or fully triangular when viewed on a front and/or side X-ray. The abnormally shaped vertebra may cause a wedge in the front, back, or either side, or a combination, tilting the spine at that level. Regular X-rays are limited because they only show a two-dimensional representation of a three-dimensional problem. The other major type of malformation is “failure of segmentation”. This means that one or more vertebrae are abnormally connected together on one side. This connection will slow growth on the connected side while the unconnected side continues to grow. Your scoliosis surgeon will often use descriptive terminology to designate how much growth potential may be in the congenital anomaly.
In the thoracic (chest) part of the spine, congenital anomalies of the ribs often correspond with the 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. At times the spine is tethered by a fusion of the ribs alone. This may lead to thoracic insufficiency syndrome if the chest cavity cannot grow properly. Furthermore, a child with congenital spine anomalies often has more than one. There can be a mix of wedged and connected vertebrae. At times the malformations can correct the deformity [a wedged vertebra (hemi-vertebra) on the left side and another on the right ]. Other times, multiple anomalies can accentuate the curvature (two same-sided hemi-vertebra on the same side). It is not uncommon that wedges on opposite sides of the spine cancel out the deformity. Therefore, the presence of malformed vertebrae is not a problem unless they cause the spine to tilt significantly out of alignment.
Evaluation & Prognosis
After the history and physical examination, the next step in evaluating congenital scoliosis is obtaining X-rays. Good quality anterior/posterior (front view) and lateral (side view) X-rays are necessary. X-rays should include the neck and thoracolumbar (shoulders-to-waist) spine. The three-dimensional structure of the abnormal bone(s) may be best visualized with CT scan because three-dimensional reconstructions of the spinal anatomy are possible MRI is also valuable to rule out associated anomalies in the spinal cord, and better define the nerve and disc anatomy. In children less than 3 months (before the vertebrae ossify and harden), an ultrasound examination can scan the spinal cord for abnormalities without the need for sedation. Your scoliosis surgeon may also advise your pediatrician to obtain an ultrasound of the kidneys or a cardiology consult. Because the kidneys and heart are formed at the same time as the vertebra, something that affects the spine may affect other organs. Children with congenital scoliosis have a 25% chance of having an anomaly of the urologic system (kidneys, bladder) or 10% chance in the cardiac system. The child’s limbs should be examined for any musculoskeletal
abnormalities, such as clubfoot or malformed hand or arm.
When your child’s congenital spine anomaly is first diagnosed, no one will know exactly how much the spinal deformity will progress as the child grows. There are some clues, however. Anomalies in the thoracic spine tend to progress more. Multiple fully-segmented hemi-vertebrae (triangular vertebra with discs between them) on the same side of the spine tend to progress more. A hemi-vertebra opposite a set of fused vertebrae (bar) is the most likely combination to progress as the child grows. Because of the rapid period of spinal growth in the first 5 years of life, and similarly during adolescence, curves must be monitored closely during these periods.
Observation is usually the first method of treatment for a young child with a spinal deformity. The physician will first need to determine if the curvature is progressing or worsening. Some children will have a curvature of their spine that is stable and unchanging, whereas other children will have a curve that relentlessly progresses. Just because the spinal deformity surgeon is “observing” your child does not mean that he/she is not treating them. During this period of time, not only will your child’s doctor look for changes in the curve, but they will probably order some special tests to evaluate further the child’s condition and have you see some other doctors.
Your scoliosis surgeon will probably want to see your child every four to six months and have new X-rays made. They will then measure the curves and compare them with the previously made films. The doctor will probably continue to observe your child’s curves as long as there is no drastic increase in the size of the curve. If your surgeon documents progression of the curve, though, a different form of treatment will need to be instituted. The surgeon will probably want to obtain bending radiographs of the spine to assess flexibility and help
determine the next course of treatment.
If the curve is progressive and your child is still growing, the doctor will inform the parent of the lack of evidence that a brace or cast can prevent progression of a congenital scoliosis.
An operation is sometimes necessary to address spinal deformity in the young child, and the decision to do these procedures is based on many factors. The dilemma faced by the surgeon is how to stop the progression of a curve without adversely affecting future growth. Sometimes this is unavoidable, as most operations work by stopping abnormal spinal growth in a procedure called spinal fusion.
In Situ Spinal Fusion
Spinal fusion is a procedure performed to stop growth of the spine. It can be done from the back (posterior) or through the chest (anterior) or both. The joints of the spine are removed, and a bone graft is placed; when the bone heals there will be a fusion mass, or one solid piece of bone. The goal is for the many vertebrae of the spine to become one segment and stop growing crooked. In situ fusion means that the curve will be fused “where it is” with little or no correction of the spine. Sometimes instrumentation (rods, hooks, and screws) may be placed to help straighten the spine slightly and act as an internal brace for the bone graft that will form the fusion mass. When implants are not used, usually in young children, the child may need to wear a brace or cast following the operation. The goal of an in situ spinal fusion is to address the problem early, before it becomes a serious deformity.
This surgical procedure is aimed at stopping abnormal growth on one side of the spine with the hope that continued growth on the other side will result in correction of the curve over time. Every curve has a concave and convex side. If the growth centers are removed and spinal fusion is performed on the convex side, the concave side might continue to grow, possibly improving the curve. As noted, these
procedures can be unpredictable in young children with abnormal vertebrae in their back.
Some young children with scoliosis may have abnormally shaped vertebrae in their back that causes the curve. Normal vertebrae are shaped like rectangles. A hemi-vertebra (wedged vertebra) is shaped like a triangle or trapezoid. When a hemi-vertebra is located between two normal (rectangular) vertebra, a sudden, angular curve results. If this hemi-vertebra is located at the bottom of the spine, it can tilt the base of the spine and cause the child to lean to one side. In other parts of the spine, depending on the number and location of the hemi-vertebrae, severe deformity can develop. At times, the hemi-vertebra may be removed from the front, back, or both parts of the spine. Once the hemi-vertebra is removed, the vertebrae above and below it are fused together – often with instrumentation. By removing the wedged vertebra, the adjacent normal vertebra will often correct the majority of the curve. Some children will wear a brace after the operation until the spine heals. This operation has inherent risks involved – including bleeding and neurologic injury – but good spinal
correction is often achieved.
Most operations that address spinal deformity in the young child work by stopping growth. This may have unfavorable effects on growth of the thorax, lung development, and size of the trunk. The theory of the growing rod operation is to allow for continued controlled growth of the spine. This is done through the back of the spine. In general, the curve is spanned by one or two rods under the skin to avoid damaging the growth tissues of the spine. The rods are then attached to the spine above and below the curve with hooks or screws. The curve can usually be corrected by fifty percent at the time of the first operation. The child then returns every six months to have the rods “lengthened” approximately one centimeter to keep up with the child’s growth. This is usually an outpatient procedure performed through a small incision. Some children will have to wear a brace to protect the instrumentation. When the child becomes older and the spine has grown, the doctor will remove the instrumentation and perform a formal spinal fusion operation. In the past, this procedure had a very high complication rate, most of which were related to the instrumentation (hook dislodgement, rod breakage). Modern techniques reduced this complication rate to a reasonable degree.
With congenital scoliosis, this technique is valuable when there is a secondary curve adjacent to the congenital curve. At times, this curve will resolve or remain dormant if the hemi-vertebra is removed. However, if the adjacent curve progresses, it may be treated like idiopathic scoliosis, and spanned with growing rods.
Expansion Thoracoplasty and VEPTR Treatment
Congenital scoliosis in the thoracic spine often includes malformation of the ribs that may limit the growth of the lungs and chest cavity.
If the chest wall limitations (fused ribs, rib indentations, or vertebral anomalies) limit the child’s ability to breathe normally, it is called thoracic insufficiency syndrome. A technique called “expansion thoracoplasty” was developed to cut the fused ribs in order to expand the space for the lungs. This, in combination with the vertical expandable prosthetic titanium rib (VEPTR or “titanium rib”) device, have been approved by the FDA to treat the combined thoracic deformity (spine/rib cage). The procedure enlarges the constricted chest and straightens the spine indirectly without a spine fusion. VEPTR devices are placed under the scapula (shoulder blade), or near the center. The device(s) is/are attached to the ribs near the neck and continue down to either the spine, or the ribs near the waist. This helps to stabilize the surgically expanded chest wall constriction (expansion thoracoplasty). To accommodate later growth, the devices are expanded twice a year in outpatient surgery through small incisions. Your child’s spine surgeon can advise whether your child’s condition is appropriate for VEPTR treatment.
Spinal Instrumentation and Fusion
Definitive spinal fusion is performed to stop growth of the spine and thus achieve permanent correction. This treatment becomes appropriate when the patient has demonstrated significant evidence of progression of the congenital scoliosis.
Posterior fusion provides permanent stabilization in the corrected position and is achieved by removing the joints between the vertebrae to be fused, usually all the vertebrae which are involved in the curve. Bone graft – either from the pelvis, ribs, or from the bone bank (allograft) – is placed over the spine. Over time (4-6 months), the graft incorporates to the vertebral bone, and the operated portion of the spine heals into a solid block of bone. The bony fusion cannot bend, thus eliminating further progression of the curve. Typically in a child who has reached an appropriate age for definitive fusion, instrumentation will also be placed when the fusion is performed. The instrumentation rigidly fixes the spine internally, so that the corrected position is carefully preserved while the fusion takes place over the 4-6 month period. This rigid fixation is achieved by screws, hooks, and wires (“anchors”) attached to the spine, usually at multiple sites along the curve, and then rods are attached to the anchors to stiffen the entire area. Often the patient does not need any further external immobilization (cast or brace) if the internal fixation device is felt to be adequate at the time of surgery.