Principal Director, Orthopaedics, Fortis Flt. Lt. Rajan Dhall Hospital, Vasant Kunj, New Delhi
Part 2 of 8 in Adolescent Idiopathic Scoliosis
What Is Adolescent Idiopathic Scoliosis? Epidemiology and the Unknown Cause
August 4, 2024
Adolescent idiopathic scoliosis (AIS) is a coronal-plane deformity involving lateral bending of the spine, typically combined with vertebral rotation, since a genuine structural curve is almost always associated with some rotation. It becomes visible to parents, teachers or the child by around 10 to 13 years of age, and is diagnosed only once congenital, neuromuscular and syndromic causes of scoliosis have been ruled out, since none of those has an unknown cause the way idiopathic scoliosis does.
Why the cause remains unknown
Despite various theories, hormonal changes causing an asymmetric growth spurt, muscle imbalance, vertebral growth anomalies, central nervous system issues affecting trunk balance, none has been proven. A genetic link has been proposed since around 30% of AIS cases have a family member with scoliosis, but 70% do not, which weakens that theory considerably.
How common it is
AIS has a worldwide prevalence of 1-3%, the highest of any scoliotic deformity, though a diagnosis requires at least 10 degrees of coronal-plane deformity (the Cobb angle). Curves below 40 degrees generally aren't clinically obvious and don't need treatment; the clinically significant prevalence is closer to 0.1%. AIS shows a preference for female patients and right-sided curves, though the reason for either preference, like the condition's cause overall, is not known. AIS constitutes about 80% of all scoliosis cases, and the younger the age of onset, the more the deformity tends to progress, since more growth remains.
This article is based on a Jivo Masterclass session conducted by Dr. Manoj Miglani, Principal Director, Orthopaedics, Fortis Flt. Lt. Rajan Dhall Hospital, Vasant Kunj, New Delhi. The article has been summarised with the assistance of an AI tool from the original masterclass recording. Watch the full Masterclass recording
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This guide is based on a live Jivo Masterclass: Dr. Manoj Miglani taught doctors across Africa on August 4, 2024.
FROM THE LIVE Q&A
Huzer Kadindwe
As a traumatic scoliosis patient from DRC with a Cobb angle of 22 degrees, should I wear a custom-made corset or a removable corset with physiotherapy sessions?
Dr. Manoj Miglani
At a Cobb angle of 22 degrees, correction may not be needed at all. If there is no pain in the affected area of the spine, the curve is unlikely to progress further and has likely already stabilised, so no bracing or active intervention is required. X-ray pictures and clinical photos would be needed for a fuller review of the specific case.
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Frequently Asked Questions
Can you say something regarding intraoperative monitoring during operative treatment of AIS?▼
Intraoperative neuromonitoring is used routinely for curves more than 60-70 degrees, which makes the surgery much safer. The monitoring system stays active throughout the procedure, with checks after every screw placement and after every corrective manoeuvre, which is what keeps neurological complication rates under 1%, even for nerve root injury.
When treating AIS with bracing: how many hours per day should a brace be worn, what are the indications for considering the treatment a failure, and when should surgical options be considered after failure of bracing as non-operative management?▼
A brace should be worn for 22 hours a day to be effective. Treatment is considered a failure if the deformity progresses both clinically and radiologically despite bracing. Surgery should be considered once the child has more than 40 degrees of deformity with growth still remaining.
What are the most common complications after surgical management of scoliosis, and how are they prevented?▼
Routine complications similar to other major surgeries: bleeding, infection, paralytic ileus, and malposition of hardware. Specific rates are neurological injury under 1%, respiratory complications 2-8%, infection under 1%, and mesenteric artery issues around 2.7%, kept low through routine intraoperative neuromonitoring and surgical volume/experience at the centre.
Is adolescent idiopathic scoliosis hereditary?▼
Around 30% of adolescent idiopathic scoliosis cases have a family member with scoliosis, suggesting some hereditary or familial component, though it's far from universal. Congenital scoliosis and some neuromuscular or syndromic forms of scoliosis have a much stronger chance of being hereditary, since they involve clearer genetic transmission.
For a patient being observed with a curve between 10 and 20 degrees, is it okay to start some physiotherapy or rehabilitation exercises, or does one have to wait?▼
At 10 to 20 degrees, the focus should just be on exercises to keep the back muscles healthy and avoiding extremes of posture, that is all that is needed. Follow-up frequency with X-rays, whether every 3 months, 6 months or a year, depends on the child's age and Risser sign, not on whether they are doing exercises.
What causes adolescent idiopathic scoliosis?▼
The exact cause is unknown. Theories include hormonal growth-spurt effects, muscle imbalance, vertebral growth anomalies and central nervous system factors, but none has been proven.
How common is AIS?▼
1-3% worldwide, the highest prevalence of any scoliotic deformity, though only about 0.1% of cases are clinically significant enough (over 40 degrees) to be obvious or need treatment.
In This Series: Adolescent Idiopathic Scoliosis
- 1.Adolescent Idiopathic Scoliosis
- 2.What Is Adolescent Idiopathic Scoliosis? Epidemiology and the Unknown Cause
- 3.Diagnosing and Classifying Scoliosis: Cobb Angle, Curve Types and True vs Postural Deformity
- 4.The Risser Sign: Predicting Whether a Scoliosis Curve Will Progress
- 5.Treatment Thresholds: Observation, Bracing and Surgery by Curve Severity
- 6.Why Bracing Has Real Limits: Brace Types, Compliance and When It Fails
- 7.Surgical Correction: From the Harrington Rod to Modern Pedicle Screw Fixation
- 8.Scoliosis Complications: Untreated Progression, Surgical Risk and a Post-Traumatic Case