High Yield Overview
Juvenile Idiopathic Scoliosis
Age 4-10 Years
4 to 10 yearsAge
Greater than 70%Progression rate
20%Neural Axis Abnormalities
RareResolution
C-EOS Risk Stratification
Low Risk
PatternCobb less than 30 deg. Risser 0.
TreatmentBrace/Observe
High Risk
PatternCobb greater than 30 deg. Progression greater than 10 deg/year.
TreatmentSurgery (Growing Rods)
Critical Must-Knows
- Malignant Progression: Very high risk of becoming severe before skeletal maturity.
- MRI Mandatory: 20% have intraspinal pathology (Arnold-Chiari, Syrinx, Tethered Cord).
- Lung Development: Alveolar multiplication continues until age 8 (avoid early fusion!).
- Casting Limit: Rarely effective after age 4 due to stiffness.
- Treatment Gap: Often requires 'Growth Friendly' surgery (growing rods).
Examiner's Pearls
- "Full neurological exam is critical (Abdominal reflexes)
- "Look for cafe-au-lait spots (NF1)
- "Assess flexibility (Bending films)
- "Check lung function (if cooperative)
Clinical Imaging
Imaging Gallery
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The MRI Rule
Juvenile Scoliosis = MRI Spine.
- In Adolescent Idiopathic Scoliosis (AIS), MRI is reserved for "Red Flags".
- In Juvenile Scoliosis, the condition ITSELF is a red flag.
- Approximately 20% of patients with "Idiopathic" Juvenile Scoliosis have a neural axis abnormality (Chiari 1 malformation, Syringomyelia). These require neurosurgical decompression before scoliosis correction.
Juvenile vs Adolescent Idiopathic Scoliosis
| Feature | Juvenile (4-10) | Adolescent (10+) |
|---|---|---|
| High (20%) | Low (2-4%) | |
| Very High ('Malignant') | Variable (Depends on Risser) | |
| Female > Male | Female >>> Male | |
| Moderate (Age 4-8 critical) | Low (Lungs developed) |
Mnemonic
Red Flags in Juvenile Scoliosis
L
Left
Left thoracic curve (Check MRI)
P
Pain
Significant night pain (Tumor/Infection)
N
Neuro
Abnormal reflexes (Syrinx)
R
Rapid
Rapid progression (greater than 10 deg/6mo)
Memory Hook:LPN-R (Licensed Practical Nurse - Rapid response).
Mnemonic
Goals of Treatment
P
Prevent
Prevent severe deformity (greater than 90 deg)
P
Preserve
Preserve lung growth (TIS prevention)
P
Postpone
Postpone definitive fusion until age 10-12
Memory Hook:Triple P.
Mnemonic
Surgical Options
G
Growing Rods
Distraction based (MCGR/TGR)
S
Shilla
Growth guidance
V
VEPTR
Chest expansion
T
Tethering
VBT (Anterior Growth Modulation)
Memory Hook:GSVT (Great Spines Very Tall).
Overview/Epidemiology
Juvenile Idiopathic Scoliosis (JIS) occupies the age range of 4 to 10 years.
- The "Grey Zone": It exists between the resolving potential of Infantile scoliosis and the predictable patterns of Adolescent scoliosis.
- Epidemiology:
- Accounts for approx 10-15% of all idiopathic scoliosis.
- Female Predominance: Similar to AIS, females are more commonly affected.
- Right Thoracic: The curve pattern begins to resemble AIS (Right sided).
- Malignancy: It is often termed "malignant" because the child has a huge remaining growth potential (the pre-pubertal growth spurt lies ahead). A 30 degree curve at age 5 will almost certainly be greater than 100 degrees by maturity if untreated.
Pathophysiology and Mechanisms
Lung Development
- Alveolar Phase: From birth to age 8, alveoli multiply in number.
- Hypertrophy Phase: After age 8, alveoli increase in size but not number.
- Implication: Early fusion (or severe deformity) before age 8 results in a permanent reduction in alveolar number (True pulmonary hypoplasia). Fusion after age 10 typically has minimal impact on pulmonary function.
Neuroaxis Abnormalities
- Chiari 1 Malformation: Herniation of cerebellar tonsils greater than 5mm.
- Syringomyelia: Fluid filled cyst in the spinal cord.
- Mechanism: The syrinx expands the cord preferentially on one side, damaging the anterior horn cells that innervate the paraspinal muscles. This creates a muscle imbalance that drives the scoliosis.
Classification Systems
Lenke Classification?
- While the Lenke classification is designed for AIS, it is often applied to older juvenile patients (age 8-10) to describe the curve pattern.
- Utility is limited because "Triple Major" patterns are less common than long neurological C-curves or simple Thoracic curves.
Clinical Assessment
History:
- Pain: Night pain, back pain. (Red flag for tumor/syrinx).
- Neurology: Headaches? Change in bowel/bladder? (Chiari/Tethered cord).
- Family Hx: Strong scoliosis history.
Physical Exam:
- Cutaneous Markers: Hairy patches, dimples, hemangiomas.
- Neurology:
- Abdominal Reflexes: Stroking the abdomen should cause umbilicus to deviate towards the stimulus. Asymmetry = Syrinx until proven otherwise.
- Lower Limb: Cavovarus feet (Charcot-Marie-Tooth or Dysraphism).
- Adams Forward Bend Test: Quantify the rib hump (Scoliometer).
Investigations
Primary Imaging:
- PA and Lateral Whole Spine X-ray.
- Supine/Bending Films: To assess flexibility. This determines if bracing is viable (flexible) or if release is needed (stiff).
Neuroimaging:
- MRI Whole Spine: Mandatory for all Juvenile Scoliosis greater than 20 degrees.
- Must image Brainstem to Sacrum.
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Management Algorithm
1. Bracing (TLSO)
- Indication: Curves 25-45 degrees, Risser 0, Flexible.
- Efficacy: Less effective than in AIS. "Part-time" bracing (night only) is useless. Requires 20-23 hours/day.
- Goal: Delay surgery. Usually cannot prevent surgery eventually, but delays it until age 10-12 (lung maturity).
2. Casting
- Indication: Rarely used after Age 5. Useful if failing brace to "buy time".
Clinical Algorithm
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Surgical Techniques
Growing Rods (MCGR)
- Technique: Proximal anchors (T2/3 hooks/screws) and Distal anchors (L3/4 screws). Submuscular rods.
- Magnet: External magnet lengthens the rod 3-5mm every 3 months in clinic.
- Advantage: Avoids "Law of Diminishing Returns" (spontaneous autofusion from repeated open surgeries).
- Disadvantage: Metal artifact on MRI (makes monitoring syrinx difficult). Cost.
Deep Dive: The Crankshaft Phenomenon
Definition: Progressive rotational and angular deformity that occurs after posterior fusion in skeletal immature patients.
Mechanism:
- Posterior elements are fused (tethered).
- Anterior vertebral bodies (neurocentral synchondrosis) continue to grow.
- Result: The spine bulges anteriorly and twists (rotates) around the posterior tether.
Prevention:
- In Risser 0 patients with open triradiate cartilage (Age less than 10), posterior fusion ALONE is contraindicated.
- Must perform Anterior and Posterior Fusion (circumferential) to stop all growth plates if definitive fusion is chosen.
The Law of Diminishing Returns With traditional distraction-based surgery (TGR):
- Every time you operate to lengthen the rods, the spine scars and stiffens ("Auto-fusion").
- The amount of length gained per surgery decreases over time.
- By the 5th or 6th lengthening, the spine may be completely stiff, yielding zero length gain, but all the risks of surgery remain.
- Solution: Minimise interventions (use MCGR) or delay initial implantation as long as possible.
Complications
| Complication | Rate | Prevention/Management |
|---|---|---|
| Implant Failure | High | MCGR rods jam. Anchors pull out. |
| Infection | Moderate | Increased with multiple surgeries (less with MCGR). |
| PJK | Common | Proximal Junctional Kyphosis. Avoid stopping at kyphotic apex. |
| metallosis | Unknown | Titanium debris from sliding rods (Shilla). |
| Neurological | Rare | Monitor cord during lengthening. |
Postoperative Care
- Bracing: Most growing rod patients require a brace post-op to protect the proximal anchors.
- Activity: Restricted contact sports.
- Lengthening: Strict adherence to lengthening schedule (usually every 3 months for MCGR).
Outcomes/Prognosis
- Untreated: Severe disability, restrictive lung disease, Cor Pulmonale.
- Treated:
- Most require definitive fusion at maturity.
- Goal is a "straight-ish" spine with adequate lung strings.
- Final height is usually short (short trunk), but functional.
- Pain: Adults with treated JIS have higher rates of back pain than AIS patients.
Evidence Base
Classic
📚 Robinson and McMaster
Key Findings:
- Natural history of Juvenile Scoliosis
- High rates of progression in curves greater than 30 degrees
- Progression continues even after skeletal maturity if severe
Clinical Implication: Aggressive treatment is warranted.
Source: JBJS Br 1996
Level IV
📚 Gupta and Lenke
Key Findings:
- Neural axis abnormalities in Juvenile Scoliosis
- Incidence 27%
- Recommends MRI for all patients less than 10 years old
Clinical Implication: MRI is mandatory.
Source: Spine 2002
Level III
📚 Akbarnia et al
Key Findings:
- Dual vs Single Growing Rods
- Dual rods are stronger and provide better correction
- Lower implant failure rate
Clinical Implication: Use dual rods.
Source: Spine 2008
Level III
📚 Cheung et al
Key Findings:
- MCGR (Magnet) vs Conventional Growing Rods
- Fewer planned surgeries
- Similar complication profile (implant failure still common)
- Better psychological scores
Clinical Implication: MCGR is preferred.
Source: Spine 2016
Level III
📚 Bess et al
Key Findings:
- Complications of Growing Rod treatment
- 58% complication rate per patient
- Risk of complication increases with every surgery performed
Clinical Implication: Law of Diminishing Returns.
Source: JBJS Am 2010
Level III
📚 Karol et al
Key Findings:
- Lung function after early fusion
- Fusion of greater than 4 segments before age 8 leads to restrictive lung disease
- Proximal thoracic fusion is worst
Clinical Implication: Delay fusion until age 10.
Source: JBJS Am 2008
Viva Scenarios
Practice these scenarios to excel in your viva examination
VIVA SCENARIOStandard
The Malignant Progression
EXAMINER
"6-year-old female. Right Thoracic curve 35 degrees. MRI is normal. Risser 0."
EXCEPTIONAL ANSWER
This is a classic Juvenile Idiopathic Scoliosis. With a curve of 35 degrees at age 6, this is highly likely to progress (Malignant curve). Observation is not appropriate. **Bracing** (TLSO) is the first line treatment to delay progression, but parents must be warned of high failure rates. If it progresses despite bracing to greater than 50 degrees, **Growing Rods** (MCGR) would be the next step. Fusion should be avoided this young.
KEY POINTS TO SCORE
High progression risk
Brace to buy time
Avoid early fusion
COMMON TRAPS
✗Observing a 35 deg curve
✗Fusing at age 6
LIKELY FOLLOW-UPS
"What specific bracing protocol would you prescribe?"
VIVA SCENARIOStandard
The Syrinx
EXAMINER
"8-year-old male. Left Thoracic curve. MRI shows a large thoracic syrinx."
EXCEPTIONAL ANSWER
The syrinx is the likely cause of the scoliosis. I would refer to **Neurosurgery** for decompression (Foramen Magnum Decompression / Shunting). The scoliosis treatment should be paused (unless severe/threatening). In many cases (approx 30-50%), the scoliosis may improve or stabilize after the syrinx is decompressed. If it persists or progresses after neurosurgery, then treat the scoliosis (Brace/Surgery).
KEY POINTS TO SCORE
Treat the cause first
Neurosurgery referral
Wait for resolution
COMMON TRAPS
✗Instrumenting the spine with a syrinx (Risk of paralysis)
✗Ignoring the Left curve red flag
LIKELY FOLLOW-UPS
"How long do you wait after neurosurgery to instrument?"
VIVA SCENARIOStandard
Crankshaft in a 9-year-old
EXAMINER
"A 9-year-old underwent posterior fusion for severe scoliosis 2 years ago. Now the deformity is recurring and she is twisting."
EXCEPTIONAL ANSWER
This is the **Crankshaft Phenomenon**. The posterior tether has stopped posterior growth, but anterior growth has continued, causing rotation. Radiographs will show the "Sunset sign" or "Double rib contour". Management requires **Anterior Fusion** (discectomies and fusion) to stop the anterior growth engine, and potentially osteotomies to correct the deformity if severe.
KEY POINTS TO SCORE
Continued anterior growth
Anterior fusion required
Prevention is key
COMMON TRAPS
✗Thinking it's just pseudarthrosis
✗Revising posteriorly only
LIKELY FOLLOW-UPS
"At what Risser stage is Crankshaft no longer a risk?"
MCQ Practice Points
Pathomechanics MCQ
Q: At what age does the risk of true pulmonary hypoplasia (loss of alveolar number) significantly decrease? A: Age 8. Fusion after age 8 generally affects lung volume (size) but not alveolar count.
Complication MCQ
Q: What is the most common cause of growing rod failure? A: Anchor failure (Hook/Screw pullout) or Rod Fracture.
Diagnosis MCQ
Q: What clinical sign is most specific for a syrinx in a child with scoliosis? A: Absent abdominal reflexes. (Asymmetrical superficial abdominal reflex).
Treatment MCQ
Q: A 5-year-old has a 60 degree congenital scoliosis (Unilateral unsegmented bar with contralateral hemivertebra). Treatment? A: Fusion. Congenital curves DO NOT respond to bracing. A short fusion of the congenital anomaly is required to stop the "evil" growth mismatch. Growing rods are for long curves (idiopathic/NM).
Neural Axis
Q: What percentage of patients with juvenile idiopathic scoliosis have a neural axis abnormality (Chiari/Syrinx) on MRI? A: Approximately 20%. This is why MRI is mandatory for all juvenile scoliosis patients.
Australian Context
- Funding: MCGR (Magnet rods) are funded by the Prostheses List but require specific indication codes.
- Radiation: Frequent X-rays in juvenile patients raise concerns about breast cancer risk. Most Australian centres use EOS Imaging (Low dose bi-planar slot scanning) which reduces radiation dose by 90% compared to standard digital X-ray.
- Transition: Dedicated transition clinics exist in major cities to hand over complex juvenile/infantile patients to adult spinal surgeons at age 16-18.
JUVENILE SCOLIOSIS
High-Yield Exam Summary
BASICS
- •Age 4-10
- •High Progression
- •MRI Mandatory
- •The Grey Zone
RED FLAGS
- •Left curve
- •Pain
- •Neuro Signs
- •Rapid Increase
THE LUNGS
- •Alveoli Age 8
- •TIS Risk
- •Avoid Early Fusion
- •Volume is Life
SURGERY
- •Growing Rods
- •Shilla
- •Tethering (VBT)
- •Delay Fusion
Deep Dive: Vertebral Body Tethering (VBT)
The New Kid on the Block VBT is a "growth modulation" technique (like 8-plates for knees).
- Indication: Skeletally immature (Risser 0-2), Flexible curve, Age 8-12.
- Mechanism: Screws placed laterally in vertebral bodies on the convex side. A flexible polyethylene cord connects them. Tension is applied.
- Result: Compression of the convex growth plate slows growth. Concave side keeps growing. The spine straightens as the child grows.
- Controversy: High revision rate (tether rupture, over-correction). Long term results unknown. FDA approved (HDE) but still considered "innovative" in many guidelines.