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Congenital Scoliosis

A Patient Guide to Anatomy, Classification, Natural Course, and Treatment Options for Spinal Curves Present at Birth

In This Guide

What congenital scoliosis is, and how it differs from other types of scoliosis

How the spine normally forms before birth, and what goes wrong in this condition

The three types of vertebral anomaly and why classification predicts risk

Why babies are screened for spinal cord, heart, and kidney anomalies

What typically happens without treatment, based on the type and location of the anomaly

Evidence-based treatment options, from observation to growth-friendly surgery

What Is Congenital Scoliosis?

Congenital scoliosis is a sideways curve of the spine that is present at birth because one or more of the small bones of the spine (vertebrae) did not form correctly while the baby was developing in the womb. The word “congenital” simply means “present at birth.” This is different from scoliosis a child develops later, or that an adult develops from aging — in congenital scoliosis, the bones themselves are the wrong shape from the very start.

Congenital scoliosis is uncommon, estimated to occur in roughly 0.5 to 1 out of every 1,000 live births. It makes up about 10% of all scoliosis cases seen by spine specialists. Some children are diagnosed on a prenatal ultrasound before birth; others are not identified until a pediatrician or parent notices an uneven back, shoulders, or waistline in infancy or early childhood.

Congenital vs. Idiopathic vs. Degenerative Scoliosis

Patients and parents often hear the general word “scoliosis” used for very different conditions. Next Era Spine Care has separate companion guides for idiopathic scoliosis and de novo degenerative scoliosis — here is how all three compare at a glance:

FeatureCongenital ScoliosisIdiopathic ScoliosisDe Novo Degenerative Scoliosis
When it appearsPresent at birth (though it may not be noticed until later)Develops later, typically ages 10 through the end of growthDevelops in adults, usually after age 50
Underlying vertebraeMalformed — one or more vertebrae failed to form or separate correctly before birthNormally formed — the bones themselves are shaped normallyNormally formed earlier in life, but worn down by decades of use
Root causeA structural birth defect in how the spine formed in the first trimesterUnknown (idiopathic means “cause unknown”); likely a mix of genetic and growth-related factorsAge-related wear and tear — disc thinning, joint arthritis, ligament changes
Typical patientInfants and young childrenAdolescents, more often girlsAdults, usually over 50–60
Associated anomaliesOften linked to spinal cord, heart, and kidney anomalies (e.g., VACTERL association)Usually an isolated spine finding, without other organ anomaliesUsually an isolated spine finding, sometimes with spinal stenosis
This handout / companion guidesCovered in this guideCovered in a companion Next Era Spine Care guideCovered in a companion Next Era Spine Care guide

The Anatomy: Normal Vertebral Formation vs. This Condition

A normal spine is built from a stack of block-shaped bones called vertebrae, separated by cushioning discs. Each vertebra normally forms as a complete, symmetrical block with a growth plate (disc space) on its top and bottom, allowing both sides of the spine to lengthen evenly as a child grows.

In congenital scoliosis, this normal building process goes wrong for one or more vertebrae. Depending on what happened, a vertebra may be only partly formed (like a wedge or a half-formed hemivertebra), or two vertebrae may fail to separate from each other properly, fusing along one side. Because the affected side either has extra growth (from an oddly shaped extra piece of bone) or no growth at all (from a fused bar), the two sides of the spine grow at different rates, and the spine bends toward the side that is not keeping up — similar to how a board warps if one edge is glued down while the other keeps expanding.

How It Happens: A First-Trimester Structural Birth Defect

Congenital scoliosis is not caused by anything a parent did during pregnancy — in the great majority of cases, no specific cause is ever found. The problem originates very early, during the formation of the spine itself. The building blocks of the spine, called somites, form between roughly day 20 and day 35 after conception, and the vertebrae themselves take shape between the fourth and sixth weeks of gestation, well within the first trimester. If this precisely timed process is disrupted, a vertebra may fail to form correctly or fail to separate from its neighbor. Doctors classify the resulting anomalies into three groups:

1. Failure of Formation

Part or all of a vertebra never develops. A mild version is a wedge vertebra (shorter on one side but with normal bony arches); a complete version is a hemivertebra, where an entire half of the vertebra is missing. Hemivertebrae are further described by how much growth potential they have: fully segmented (open growth plates on both sides, the most active), semisegmented (growth plate on only one side), incarcerated (growth potential present but boxed in by neighboring vertebrae, so it does not push the spine off balance), and unsegmented (fused on both sides, essentially inactive).

2. Failure of Segmentation

Vertebrae form but do not fully separate from each other. A partial failure on one side only creates an unsegmented bar, which blocks growth on that side while the opposite side keeps growing normally, steadily bending the spine toward the bar. A complete failure on both sides creates a block vertebra, which tends to grow straight because both sides are equally restricted.

3. Mixed Anomalies

Many children have a combination of both problems, sometimes at more than one level of the spine. The single most aggressive combination is a segmented (actively growing) hemivertebra on one side paired with an unsegmented bar directly across from it on the other side: one side is a wedge that keeps enlarging while the opposite side cannot grow at all.

Associated Conditions: Why Babies Are Screened Beyond the Spine

Because the spine, spinal cord, heart, and kidneys are all forming at roughly the same time in early pregnancy, a disruption severe enough to malform a vertebra can also affect these other organ systems. Associated anomalies are found in up to 61% of children with congenital scoliosis. This overlapping pattern is sometimes formally recognized as VACTERL association, an acronym for Vertebral, Anorectal, Cardiac, Tracheo-Esophageal, Renal, and Limb anomalies that can occur together. Because of this, every child newly diagnosed with congenital scoliosis is typically screened with three tests, in addition to spine X-rays:

  • Spinal MRI: Looks for anomalies of the spinal cord itself, such as a tethered cord, a split spinal cord (diastematomyelia), a fluid-filled cavity (syringomyelia), or a Chiari malformation. These spinal cord anomalies are found in roughly 20–40% of patients.

  • Renal (kidney) ultrasound: Urinary tract anomalies, such as a missing or duplicated kidney, are found in roughly 20–33% of children with congenital scoliosis.

  • Cardiac echocardiogram: Congenital heart defects occur in roughly 10–12% of children with congenital scoliosis and are checked with an ultrasound of the heart, sometimes alongside a cardiology evaluation.

All three of these studies — spinal MRI, renal ultrasound, and echocardiogram — are considered a standard part of the initial work-up for a newly diagnosed child, and the spinal MRI is considered mandatory before any spinal surgery is planned.

Natural History: Progression Depends Heavily on the Type of Anomaly

Unlike idiopathic scoliosis, where progression risk is fairly predictable from curve size and remaining growth, congenital curves behave very differently depending on exactly which vertebral anomaly is present. Overall, roughly 50–75% of congenital curves progress enough to eventually need treatment, about 25% progress only mildly, and about 25% never progress at all.

From fastest-progressing to slowest, the ranking by anomaly type is well established:

  1. Unilateral unsegmented bar with a contralateral hemivertebra — by far the fastest-progressing pattern, worsening by roughly 5 to 10 degrees per year, because one side cannot grow at all while the opposite side keeps enlarging.

  2. Unilateral unsegmented bar alone — also rapidly progressive, averaging about 7–8 degrees of worsening per year.

  3. Fully segmented hemivertebra — progressive, but generally slower than a bar, since only one side has extra growth potential rather than a complete block on the other.

  4. Unincarcerated, then incarcerated hemivertebra — lower risk, since the surrounding vertebrae partly compensate for the abnormal growth.

  5. Unsegmented hemivertebra — little growth potential, so it is much more benign.

  6. Block vertebrae — the most benign pattern; because both sides are equally fused, the spine tends to grow straight and rarely needs treatment.

Location also matters: curves in the thoracolumbar region (where the chest and lower back meet) tend to be the most severe, while curves in the upper thoracic spine tend to be the mildest. Progression is typically fastest during two windows of rapid growth: the first three to five years of life, and again during the adolescent growth spurt between roughly ages 10 and 15.

Without any treatment, about 85% of children with congenital scoliosis will have a curve greater than 41 degrees by skeletal maturity. In severe cases involving multiple rib and spine anomalies, the chest wall itself may not be able to expand enough to support normal breathing and lung growth, a serious complication called thoracic insufficiency syndrome.

When to Seek Care Right Away

Any new or worsening curve, uneven shoulders/waist, or rib prominence noticed in an infant or young child

Signs of breathing difficulty, rapid breathing, or poor weight gain, which can signal thoracic insufficiency syndrome

Any new leg weakness, foot deformity, abnormal reflexes, or changes in bowel/bladder control, which can signal a spinal cord anomaly

A skin dimple, hairy patch, or birthmark over the lower spine, which can be a marker of an underlying spinal cord anomaly

Evidence-Based Treatment Options

Treatment is guided by the specific anomaly type and location, the child’s age and remaining growth, the current curve size (measured as a Cobb angle in degrees), and how quickly the curve is changing over serial X-rays.

Step 1: Observation with Serial X-Rays

For low-risk anomalies — such as a block vertebra, an incarcerated hemivertebra, or any curve under about 25 degrees — close observation alone is often appropriate, since these patterns are unlikely to progress. A typical monitoring schedule includes standing spine X-rays roughly every 6 months during the first several years of life and through puberty, with annual checks in between during slower-growth years. Faster imaging intervals, every 4 to 6 months, are used if a curve shows early signs of progressing.

Step 2: Bracing — A Limited Role Compared to Idiopathic Scoliosis

Bracing works well in idiopathic scoliosis because those curves are flexible. Congenital curves are different: the underlying bone anomaly is rigid and structural, so a brace cannot reshape a hemivertebra or unsegmented bar the way it can guide a flexible idiopathic curve. For this reason, bracing (or serial casting in infants) is used selectively — mainly to help control a secondary, more flexible compensatory curve that develops elsewhere in the spine above or below the rigid congenital segment, rather than to correct the anomaly itself.

Step 3: Early Surgery for Progressive Curves in Young Children

Surgery is generally considered when a curve progresses faster than about 10 degrees per year, reaches roughly 40–50 degrees, or involves a high-risk pattern such as a unilateral unsegmented bar with or without a contralateral hemivertebra — especially when this occurs within the first five years of life.

  • Hemivertebra resection (hemivertebrectomy): Surgical removal of the malformed hemivertebra and its adjoining discs, most often through a posterior-only approach. This directly corrects the deformity rather than just holding it in place, with reported curve correction of roughly 60–80% and best results in children younger than about 6 to 8 years with a flexible curve under 40 degrees.

  • Growth-friendly instrumentation (growing rods): Adjustable rods attached above and below the curve that are lengthened periodically — either through repeat surgery every 6 to 12 months, or non-invasively using magnetically controlled growing rods — to control the curve while still allowing the spine to keep growing until a definitive fusion is appropriate.

  • VEPTR (Vertical Expandable Prosthetic Titanium Rib): A growth-friendly device anchored to the ribs, used specifically when rib fusions or absent ribs are restricting chest expansion and lung growth (thoracic insufficiency syndrome), rather than for the spine curve alone.

  • In-situ fusion or convex hemiepiphysiodesis: For moderate, slowly progressive curves, fusing the abnormal segment in place, or selectively slowing growth on the convex (longer) side of the curve, can prevent further worsening without needing rod lengthening.

Because growth-friendly implants and hemivertebra resection are performed in very young children with small, delicate anatomy, these procedures carry real risks, including a roughly 10–20% chance of a temporary or permanent nerve-related complication with hemivertebra resection, which is why continuous nerve monitoring during surgery is considered essential.

Bottom Line

Congenital scoliosis is caused by a structural birth defect in how one or more vertebrae formed or separated during the first trimester, not by anything that happened after birth. The single most important factor in predicting what will happen next is the specific type and location of the vertebral anomaly — a block vertebra usually needs nothing more than watching, while a unilateral unsegmented bar with an opposite hemivertebra often needs early, active treatment. Because the spinal cord, heart, and kidneys form alongside the spine, every newly diagnosed child should be screened with a spinal MRI, renal ultrasound, and echocardiogram. With early diagnosis, appropriate monitoring, and — when needed — modern growth-friendly surgical techniques, most children with congenital scoliosis can maintain a balanced spine and healthy lung function through adulthood.

Glossary of Medical Terms

Use this glossary as a quick reference for terms your care team may use during your visit.

TermWhat It Means
Congenital scoliosisA sideways curve of the spine caused by one or more spinal bones (vertebrae) that formed abnormally before birth.
Vertebra (plural: vertebrae)One of the individual bones that stack up to form the spine, normally shaped like a small, block-like cylinder.
HemivertebraA vertebra where only half formed, so it is wedge- or triangle-shaped instead of a full block, which tilts the spine toward the missing side.
Wedge vertebraA vertebra that is partly formed — shorter on one side than the other — but that still has both of its normal pedicles (bony arches), unlike a hemivertebra.
Unsegmented barA strip of bone that abnormally connects two or more vertebrae along one side of the spine, like a rigid metal brace stapled along one edge, blocking growth on that side only.
Block vertebraTwo vertebrae that failed to separate from each other on both sides, fusing into one solid segment; because both sides are equally affected, it usually grows straight.
Failure of formationA category of congenital anomaly where part or all of a vertebra never formed in the first place (as in a wedge vertebra or hemivertebra).
Failure of segmentationA category of congenital anomaly where vertebrae formed but never fully separated from each other (as in an unsegmented bar or block vertebra).
Mixed anomalyA combination of both a failure of formation and a failure of segmentation, often at different spots in the same spine — typically the fastest-progressing pattern.
Segmented vs. unsegmentedWhether a growth plate (disc space) is present on each side of the abnormal vertebra; a segmented hemivertebra has open growth plates and keeps growing, while an unsegmented one is fused in place and grows very little.
Cobb angleThe standard measurement doctors use to describe how sharply the spine curves on an X-ray, expressed in degrees.
VACTERL associationA pattern of several birth differences that can occur together, spelled out by the letters: Vertebral, Anorectal, Cardiac, Tracheo-Esophageal, Renal, and Limb anomalies.
Spinal dysraphismA group of conditions where the spinal cord or its coverings did not form or close normally, including tethered cord and diastematomyelia (a split spinal cord).
Tethered cordA condition where the spinal cord is abnormally attached (tethered) to nearby tissue instead of hanging freely, which can stretch and injure it as a child grows.
Renal ultrasoundA painless imaging test using sound waves to look at the shape and structure of the kidneys and urinary tract.
Echocardiogram (echo)An ultrasound test of the heart that checks its structure and how well it is pumping.
Thoracic insufficiency syndromeA condition where the chest and rib cage cannot expand enough to support normal breathing and lung growth, often seen with severe rib and spine anomalies.
Growth-friendly surgeryA family of surgical techniques (like growing rods or VEPTR) designed to control a curve while still allowing a young child’s spine and chest to keep growing, delaying a final fusion.
Growing rodsAdjustable metal rods attached to the spine above and below a curve that are lengthened periodically (by repeat surgery or an external magnet) as the child grows.
VEPTR (Vertical Expandable Prosthetic Titanium Rib)A growth-friendly device anchored to the ribs and spine or pelvis, used mainly when rib anomalies restrict chest and lung growth.
Hemivertebra resection (hemivertebrectomy)Surgery to remove the malformed hemivertebra along with the adjoining discs, correcting the curve at its source rather than just holding it in place.
Spinal fusionSurgery that permanently joins two or more vertebrae together with bone graft and hardware so they no longer move relative to each other, stopping the curve from progressing further at that segment.

Sources

This handout is based on the following evidence-based sources:

Questions About Your Care?

This handout is for general education and does not replace personalized medical advice.

Please discuss your specific diagnosis, imaging, and treatment options with your Next Era Spine Care physician.

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