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Orthopaedic Surgery

Infantile (Idiopathic) Scoliosis

Infantile idiopathic scoliosis is a condition that affects children before the age of 3 and is characterized by the presence of an abnormal lateral curvature of the spine. This curvature causes the spinal column to bend to the left or the right, in the shape of an S or a C. The condition is seen more frequently in boys than girls. Most cases resolve spontaneously, but some may progress to more severe deformity. Treatment of infantile scoliosis may include observation, physical therapy, bracing and, under rare circumstances, surgery.

Facts about infantile scoliosis:

• Scoliosis is technically defined by the presence of a lateral curvature in the spine of >10 degrees deviation from straight upright (described further in the 'How is it diagnosed?' section).
• Most infants that develop abnormal curves do so in the first 6 months of life.
• Infantile scoliosis is a rare condition, accounting for less than 1% of all cases of idiopathic scoliosis.
• The condition is more common in Europe than in the U.S.
• For unknown reasons, the curve in the spine tends to bend to the left in infants with scoliosis. However, girls who develop curves that bend to the right have a worse prognosis than other infants.
• While there are several types of scoliosis for which the causes or origins of the disease are well understood, infantile scoliosis is considered idiopathic, which means the causes are, for the most part, unknown.
• For reasons not yet understood, it has been found that children who develop scoliosis before the age of 5 are more likely to have cardiopulmonary abnormalities in infancy.
• Infants with idiopathic scoliosis usually do not experience any pain from the condition.

The normal spine

The spine, or spinal column, as it is also called, is a complex structure made up of 33 vertebrae, or bony segments, arranged vertically in succession from just below the skull to the tailbone. The spine has two main functions: to support the weight of the skull and upper body, and to provide a protective encasement for the spinal cord, the long, cylindrical nervous structure that sends messages to and from the brain and the rest of the body. The vertebrae are attached to other vertebrae above and below them by a number of ligaments, thick fibrous structures found throughout the musculoskeletal system that attach bones to other bones. The connection points between the vertebrae are called joints, in which small areas of smooth cartilage lined with a lubricating material, known as synovial fluid, allow the bony vertebrae to slide past each other with minimal friction, allowing movement. Unlike joints such as the knee or elbow, which allow for considerable movement, each joint of the spinal column allows for very little movement because of the number of tightly attached ligaments, thereby ensuring the strength and stability of the vital supportive column. However, the joints of the spine act collectively, with the sum of movements in all the joints allowing movements such as bending forward, back, and to the side.

The normal spine actually has a number of natural curves to it, which stems from the evolution of humans from four-legged mammalian ancestors who walked on the ground bent over, with the spine parallel to the ground. However, these normal curves are antero-posterior curves only; that is, they can only be seen when looking at the spine from the side. On the other hand, when looking from directly behind or in front of a person, the spine maintains a rigid upright structure, like a straight line. In other words, there are normally no lateral curves to the human spine. Even during development in the womb, when the position of the fetal body is somewhat compacted, the spine is supposed to maintain its straight position, without any excessive lateral pressures.

Causes of infantile scoliosis

As previously mentioned, the exact cause of infantile scoliosis is unknown. However, the considerable amount of medical research that has gone into understanding scoliosis has led to the development of two main hypotheses for how the condition may be caused. There is evidence to suggest that intrauterine molding may be responsible for the development of infantile scoliosis. With intrauterine molding, the spine is affected during fetal growth because of abnormal pressures exerted by the walls of the uterus on one side of the fetus' body, or abnormal positioning of the fetus within the uterus. This hypothesis is supported by epidemiological data, which demonstrate that there are higher rates of plagiocephaly (a slight flattening of one side of the head) and developmental dysplasia of the hip (a condition that affects one of the hips) on the same side as the spinal curve in infants with idiopathic scoliosis.

A second theory suggests that postnatal external pressures are exerted on the spine after birth, perhaps due to an infant being positioned on his/her back for extended periods of time in the crib. This may explain the higher incidence of the condition in Europe, where infants have traditionally been positioned more on their backs and less on their abdomens, compared to in North America. However, a few years ago the American Academy of Pediatrics (AAP) announced a formal recommendation that newborns be positioned on their backs when sleeping, due to research studies suggesting that Sudden Infant Death Syndrome (SIDS) and other respiratory problems are associated with babies being positioned on their abdomens. Despite the possible relation of this recommended position to infantile scoliosis, our pediatric orthopaedic group supports the policy of the AAP.

A final hypothesis for a possible cause of infantile scoliosis is that of genetic inheritance. While the exact genes that may be involved have yet to be identified, research has shown that there is a higher incidence of the condition within some families, lending considerable weight to the probability of a genetic component.

Despite the notable amount evidence for these hypotheses, much about the condition remains to be discovered and fully understood. As a result, there is ongoing research at a number of academic medical centers throughout the U.S., attempting to further uncover the keys to the development of infantile scoliosis and improve the treatment and prevention of the condition.

Diagnosing infantile scoliosis

Infantile scoliosis is usually first detected in the first 6 months of life during a standard physical examination by a pediatrician, or noticed by a child's parents. When scoliosis is suspected, careful neurologic exam as well as exam of the head, back, and extremities should follow, to inspect for plagiocephaly, as described above, and to insure that the spinal cord is not being affected by another disease entity. A spinal MRI, a sophisticated radiological imaging technique, is essential to confirm the findings of the neurological exam and rule out other potential causes of scoliosis. A series of X-rays should also be taken, which allow for a more precise measurement of the severity of the curvature. As mentioned before, this requires the presence of a curvature angle of at least 10 degrees, measured with the Cobb method.

Treating infantile scoliosis

Decisions regarding the appropriate treatment for infantile scoliosis depend mostly on the severity of the spinal curvature and the likelihood that the curvature will worsen in the future. Because mild curves (10-25 degrees) very rarely progress to more severe curves and instead usually correct themselves, these children are treated only with observation. This entails simply that the child be seen regularly by an orthopaedic surgeon, who will monitor the possible progression of the curve with physical exams and X-rays. Visits must continue even into adolescence, because growth spurts may trigger progression, even in a previously non-progressive curve. When progression does occur in this group, which is rare, the patient will require casting and bracing treatment.

Infants with moderate and severe curves have a greater chance of progressing, and often require casting and bracing treatment. Casting treatment consists of serial casting, which entails that the cast be changed every 6 to 12 weeks and a new cast applied, in an attempt to gradually correct the curvature. The cast is made of plaster or fiberglass, and is applied in the operating room under general anesthesia, which means that the infant will be put to sleep through the application process, so as not to fuss or experience discomfort. Correction is usually achieved by around 18 months of age.

Casting treatment is followed up with bracing treatment, which is needed to maintain the correction. There are a number of braces available for treatment of infantile scoliosis and there is no consensus on which is the best. Further, there is no scientific evidence that bracing in infants alters the natural history of this condition. Except for bathing, and exercise the brace is to be worn all the time, usually for two to three years, after which time the child is weaned off the brace, provided correction of the curvature has been maintained. Occasionally, curves recur after brace removal, which necessitates reinstitution of full-time bracing treatment, or curves progress during bracing treatment, in which case surgery is warranted.

Surgical treatment options are generally the same for both infantile and juvenile idiopathic scoliosis. Operations may consist of instrumentation, in which metal rods are attached to the spine to maintain curve correction and/or spinal fusion, in which two or more of the vertebrae are fused together with bone bridges made of bone grafts. Surgeries may be performed through a posterior approach, in which the operation is performed with an incision in the back, or also with an anterior approach, which that requires making an opening in the chest wall to reach the front part of the spinal column. Because of the stability and effectiveness of the devices used in spine operations today, patients can be mobile the day following their surgery, and hospital stays are generally under one week.

Our spinal deformity service has added another technique in the last three years. This technique is uses instrumentation on the rib cage to provide growth of the spine and the chest without fusion. The technical name, distraction thoracoplasty, speaks to the dual goals of distraction of the hemi thoracaa to allow room in the chest for lung growth and lengthening of the spinal column to control the scoliosis.

Coping with infantile scoliosis

Managing the demands of bracing treatment for scoliosis can be a difficult task for infants and their parents alike. Surgery at such a young age, if necessary, can seem somewhat daunting as well. However, research has shown that the various treatments for infantile idiopathic scoliosis are generally extremely successful. The vast majority of children grow up without any limitations to their activities and daily functioning, from simple outdoor games to competitive sports. Thus, despite some challenging hurdles early in childhood, with treatment your child may be expected to live a normal, healthy, active life, and walk tall into adolescence and adulthood.

For more information

You may have additional questions about infantile scoliosis that are not answered in the above summary. If your child is not in the infant age group or may have another type of scoliosis, please refer to our descriptions of other types of scoliosis below.