CONGENITAL SCOLIOSIS
Pediatric Spine | Vertebral Anomalies | Early Onset | VACTERL Association
TYPE OF ANOMALY
Critical Must-Knows
- Definition: Spinal deformity caused by abnormal vertebral development in utero (first 6 weeks)
- Worst Prognosis: Unilateral unsegmented bar with contralateral hemivertebra (5-10 degrees progression per year)
- Associations: High rate of associated anomalies (VACTERL) - Renal (25%), Cardiac (10%), Intraspinal (20-40%)
- MRI Mandatory: Must screen for intraspinal anomalies (tethered cord, syrinx, diastematomyelia) before surgery
- Renal Ultrasound: Mandatory screening for all patients
Examiner's Pearls
- "Unilateral Bar + Contralateral Hemivertebra = 'Malignant' curve (rapid progression)
- "Always check kidneys (Renal US) and heart (Echo)
- "Thoracic Insufficiency Syndrome is the main mortality risk in early onset severe curves
- "Growth potential: T1-S1 grows 10cm from age 0-5, and 10cm from 10-maturity. Fusing too early creates short trunk.
Clinical Imaging
Imaging Gallery
Critical Screening Steps
Renal Anomalies
25% Association. Renal agenesis, horseshoe kidney. YOU MUST ORDER A RENAL ULTRASOUND on diagnosis. Genitourinary anomalies are the most common extraspinal association.
Intraspinal Anomalies
20-40% Association. Diastematomyelia, tethered cord, syrinx, Chiari. YOU MUST ORDER A TOTAL SPINE MRI before any corrective surgery.
Cardiac Anomalies
10% Association. VSD, ASD, Tetralogy. Listen for murmurs and refer for Echo if suspected or syndromic.
VACTERL
Vertebral, Anal, Cardiac, Tracheo-Esophageal, Renal, Limb. Look for imperforate anus, thumb hypoplasia (radial deficiency).
At a Glance: Prognosis by Defect Type
| Defect | Progression Rate | Severity | Management Action |
|---|---|---|---|
| Block Vertebra | Less than 1° / year | Benign | Observation |
| Wedge Vertebra | 1-2° / year | Mild | Observation |
| Hemivertebra (Fully segmented) | 2-5° / year | Moderate | Early surgery often required |
| Unilateral Unsegmented Bar | 5-6° / year | Severe | Fusion of bar typically needed |
| Bar + Contralateral Hemi | Greater than 10° / year | Malignant | URGENT Surgery |
VACTERLVACTERL Association
Memory Hook:A child with a bad back needs checking from top (TEF) to bottom (Anus) and limbs!
TULIPProgression Risk Factors
Memory Hook:TULIPs grow fast, and so do these curves if you miss the risk factors.
STOPSurgical Goals
Memory Hook:STOP the curve to save the lungs.
Overview and Epidemiology
Congenital Scoliosis is a lateral curvature of the spine due to vertebral malformations present at birth. Unlike idiopathic scoliosis, the deformity is structural from the outset and often rigid.
Epidemiology:
- Incidence: 0.5-1 per 1000 live births.
- No strong genetic pattern (mostly sporadic), though some familial clusters exist.
- Maternal Diabetes and valproic acid exposure are risk factors.
- Gender: Girls more common than Boys (slightly).
Natural History:
- Without treatment, 75% progress.
- Progression depends on the balance of growth.
- Thoracic Insufficiency Syndrome (TIS): The inability of the thorax to support normal respiration / lung growth. This is the main life-threatening complication of early onset severe deformities.
Pathophysiology and Mechanisms
Embryology
- Mesenchymal Stage (Weeks 4-6): This is when the axial skeleton forms.
- Somitogenesis: Somites form along the notochord.
- Re-segmentation: The caudal half of one somite fuses with the cranial half of the next to form a vertebra.
- Defects:
- Failure of Formation: Hemi-vertebra (Wedge).
- Failure of Segmentation: Unsegmented Bar (Block).
Growth Potential
- The spine grows most rapidly in the first 5 years (T1-S1 length increases 10cm) and during adolescent growth spurt (another 10cm).
- Fusion Conundrum: Fusing the thoracic spine early stops vertical growth.
- Loss of correction? No, but loss of lung volume.
- You need approx 18-22cm of T1-T12 height for adequate adult pulmonary function.
- Early fusion of greater than 4 segments in a young child can lead to TIS.
Classification
Winter's Classification (Based on X-ray)
Type I: Failure of Formation
- Incarcerated Hemivertebra: Only pedicles are deformed, body is set into the spine. Slow progression.
- Fully Segmented Hemivertebra: Disc space above and below. Acts as a growing wedge. Rapid progression.
- Semi-segmented: Fused to one adjacent vertebra.
- Wedge Vertebra: Partial formation failure.
Type II: Failure of Segmentation
- Block Vertebra: Bilateral failure. Stable, short segment. No treatment usually.
- Unilateral Unsegmented Bar: Unilateral failure. The fused side doesn't grow, the open side does. Very bad prognosis.
Type III: Mixed
- Combination of both.
- Unilateral Bar + Contralateral Hemi: The "Malignant Curve". The bar tethers one side, the hemivertebra pushes growth on the other. Rapid relentless progression.
Classification dictates urgency.
Clinical Assessment
Assessment Protocol
- Cutaneous markers of dysraphism: Hairy patch, dimple, sinus, hemangioma.
- Shoulder balance, Trunk shift.
- Facial asymmetry (Goldenhar).
- Limb deformities (Radial clubhand - VACTERL).
- Detailed lower limb neuro exam.
- Reflexes (Abdominal reflexes often absent in extensive syrinx).
- Ankle clonus (Tethering).
- Cardiovascular exam (Murmurs).
- History of renal issues or UTIs.
- Anal patency.
The Cutaneous Stigmata
Always look at the skin over the spine. A hairy patch (faun's beard) or deep dimple is highly suggestive of underlying spinal dysraphism (spina bifida occulta, diastematomyelia).
Investigations
Imaging Modalities
| Modality | Indication | What to look for |
|---|---|---|
| X-ray (Whole Spine) | First line | Count vertebrae, identify bars/hemis, measure Cobb angle. |
| Renal Ultrasound | Mandatory | Renal agenesis (25%). |
| MRI Total Spine | Mandatory pre-op | Tethered cord, Syrinx, Diastematomyelia, Chiari. |
| CT Scan (3D Recon) | Pre-op planning | Visualize complex bony anatomy, pedicle morphology for screws. |
| Echocardiogram | Mandatory | Cardiac flow anomalies. |
Diastematomyelia Spur
The Spur Must Go First. If a bony spur (diastematomyelia) is present, you cannot distract/straighten the spine until it is excised. Distraction against a spur will split the cord (neurological catastrophe).
Management Algorithm
Observation
- Indications: non-progressive curves, block vertebrae, balanced deformities.
- Protocol: X-ray every 6-12 months during growth.
Bracing?
- Role: Limited to NONE.
- Congenital curves are rigid and do not respond to bracing.
- Exception: Occasionally used to control compensatory curves above/below the congenital defect to delay surgery.
Observation requires strict radiographic intervals.
Surgical Technique
Posterior Fusion of Unsegmented Bar
Goal: Stop the "bad" side from not growing? No, stop the good side? Actually, treating a bar involves fusing the bar to stop any growth, and often fusing the convex (growing) side? No.
Correct Logic: An unsegmented bar has NO growth plates. The contralateral side has normal growth plates. This causes the curve. Surgery: Convex Epiphysiodesis. Stop the growth on the convex (healthy) side to match the lack of growth on the concave (bar) side.
- Approach: Posterior or combined A/P.
- Ablate the growth plates/discs on the convex side.
- Apply fusion mass.
- Result: arrest of progression (maybe some auto-correction).
Early intervention prevents severe deformity.
Complications
Surgical Complications
| Complication | Risk Factor | Management |
|---|---|---|
| Neurological Injury | Osteotomy, Diastematomyelia distraction | IOM monitoring. Wake up test. Remove spurs first. |
| Crankshaft Phenomenon | Posterior fusion with open anterior growth plates in young child | Add anterior fusion or exclude growth plates. |
| Infection | Long revisions, syndromes | Washout, antibiotics. |
| Implant Failure | Growing rods, poor bone stock | Revision. |
| PJK | Proximal Junctional Kyphosis | Extension of fusion. |
Postoperative Care and Rehabilitation
Protocol
- ICU observation (neuromonitoring considerations).
- Pain control.
- Mobilize as tolerated (no brace usually needed if rigid fixation).
- Wound checks.
- Return to school.
- No impact sports.
- X-ray to assess arthrodesis.
- Gradually increase activity.
- Monitor for Crankshaft (if young).
- Monitor for PJK.
- Lung function tests.
Outcomes
Prognosis:
- Hemivertebrae: Excision yields excellent correction and balance.
- Unsegmented Bars: Early convex epiphysiodesis can halt progression but rarely corrects deformity substantially.
- Untreated: Can lead to severe deformity (greater than 100 degrees), Cor Pulmonale, and early death from respiratory failure.
Evidence Base
Natural History of Congenital Scoliosis
- Seminal paper reviewing 251 patients
- Identified the 'Malignant Curve' (Unilateral bar + contralateral hemivertebra)
- Established progression rates for different anomalies
- Block vertebra = benign. Bar + Hemi = rapid progression
Hemivertebra Excision Results
- Posterior-only resection of hemivertebrae (transpedicular)
- Average correction 70%
- Low complication rate in experienced hands
- Eliminated need for anterior approach
Thoracic Insufficiency Syndrome
- Coined term TIS
- Described VEPTR (Vertical Expandable Prosthetic Titanium Rib)
- Expand thorax volume to allow lung growth
- Improved survival in severe early onset cases
Renal Anomalies Screening
- High association of intraspinal anomalies
- Review of congenital scoliosis patients
- Strong recommendation for renal and spinal screening
Early Fusion and Lung Growth
- Evaluated pulmonary function after early thoracic fusion
- Fusion length greater than 60% of thoracic spine before age 10 results in restrictive lung disease
- T1-T12 height less than 18cm associated with respiratory insufficiency
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
"A newborn baby is noted to have a spinal deformity. X-ray shows a hemivertebra at L1. The parents ask if surgery is needed now."
"A 6-year-old boy presents with a worsening thoracolumbar curve. X-rays show a unilateral unsegmented bar on the left from T10-L2 with multiple hemivertebrae on the right."
"You are performing a hemivertebra excision. During the osteotomy, the neuromonitoring signals (MEPs) drop bilaterally."
MCQ Practice Points
Most Common Anomaly
Q: What is the most common intraspinal anomaly associated with congenital scoliosis? A: Diastematomyelia (Split cord malformation), followed by tethered cord and syrinx.
Progression Hierarchy
Q: Rank the following from worst to best prognosis: Block Vertebra, Fully Segmented Hemivertebra, Unilateral Bar + Contralateral Hemi. A: Worst: Bar + Contralateral Hemi. Middle: Fully Segmented Hemi. Best: Block Vertebra.
VACTERL Definition
Q: How many features are needed to diagnose VACTERL association? A: Typically at least 3 of the 6 features (Vertebral, Anal, Cardiac, TE, Renal, Limb).
Cord at Risk
Q: Why is an MRI mandatory before casting or surgery in congenital scoliosis? A: To rule out intraspinal anomalies (e.g. syrinx, tethering). Correcting the curve stretches the spinal canal; if the cord is tethered, this stretch causes ischemia and paraplegia.
Klippel-Feil Triad
Q: What is the classic triad of Klippel-Feil syndrome? A: 1. Low posterior hairline. 2. Short neck ("Webbed"). 3. Limited cervical range of motion.
Goldenhar Syndrome
Q: A child with scoliosis has ear tags and facial asymmetry. What is the diagnosis? A: Goldenhar Syndrome (Oculo-auriculo-vertebral spectrum).
Australian Context
Epidemiology:
- Managed in major pediatric spine centers.
- NDIS (National Disability Insurance Scheme) support often required for syndromic cases.
Referral Pathways:
- All congenital scoliosis should be referred to a pediatric spine surgeon.
- General orthopaeds should order the screening Renal US and X-rays but not manage the curve.
High-Yield Exam Summary
VACTERL Checklist
- •Vertebral (X-ray)
- •Anal (Exam)
- •Cardiac (Echo)
- •TE (History/Swallow)
- •Renal (Ultrasound)
- •Limb (Radius exam)
McMaster Prognosis
- •Block: Benign
- •Wedge: Mild
- •Hemi: Moderate
- •Bar: Severe
- •Bar+Hemi: Malignant
Key Principle
- •MRI before Surgery/Bracing
- •Renal US for everyone
- •Preserve lung volume (TIS risk)
- •Don't fuse greater than 4 segments early
- •Check for Diastematomyelia spur