01Understanding what scoliosis is
Scoliosis is a three-dimensional deformity of the spine: it curves sideways and some vertebrae rotate. This rotation can change the shape of the ribs or back. Scoliosis differs from a simple postural asymmetry, which does not have the same features.
In adolescents, the most common form is called idiopathic scoliosis: no specific cause is identified after assessment. There may be a family predisposition. Carrying a schoolbag or sitting in a poor position are not recognised causes of this form of scoliosis; the child is not responsible for it.
Simplified diagrams, not to scale. The Cobb angle does not measure this rotation.
02Noticing asymmetry and seeking advice
One shoulder sitting higher, a more prominent shoulder blade or uneven waist creases may draw attention. However, scoliosis can go unnoticed and cause no pain. Routine child health checks are therefore useful, particularly around puberty.
The clinician examines the back while the child is standing and then bending forwards, looking for a rib or back prominence on one side. Further examination depends on the circumstances. An observation at home or a photograph is not enough to diagnose scoliosis; persistent pain or a rapid change should be reported.
03Understanding the X-ray and the Cobb angle
When the spinal deformity needs to be confirmed, an X-ray of the whole spine helps describe the curves. The Cobb angle measures the curve using the vertebrae at its ends. It is an important measure for monitoring progression, but it does not describe every aspect of scoliosis on its own.
The care team interprets the images alongside the back examination and the amount of growth remaining. They select appropriate tests and aim to limit X-ray exposure. Some systems, such as EOS, produce low-dose images; MRI answers different questions and is not routinely requested for every adolescent.
What does the Cobb angle measure?
Move the slider: the tilt of the two vertebral endplates changes. The angle between the lines perpendicular to them changes by the same amount.
This is a geometric example. The slider does not represent your back or determine any treatment. Vertebral rotation and growth are assessed in other ways.
04Why growth matters so much
Two adolescents with the same Cobb angle may need different care. The initial curve matters, as do its progression and the amount of growth still to come. The pubertal growth spurt is a period that requires particular attention.
To estimate skeletal maturity, the specialist combines several findings and may use a bone maturity score: Risser on the pelvis or Sanders on the hand. These measures provide information beyond chronological age. The first menstrual period alone does not mean that growth is complete or that follow-up can stop.
Frequently asked questions
What is the difference between scoliosis and poor posture?
Scoliosis involves both a curve and rotation of the vertebrae. A simple postural asymmetry does not have the same features. A doctor distinguishes between them through examination and imaging when needed.
Can scoliosis be present without pain?
Yes. Uneven shoulders, waist creases or the shape of the back may be noticeable even when a child has no symptoms. A new asymmetry should be assessed during a medical examination.
What does a Cobb angle of 20 or 30 degrees mean?
It describes the size of a curve on an X-ray. On its own, it does not indicate the level of pain or which treatment to choose. Progression, remaining growth and the type of curve also matter.
Does scoliosis stop progressing after the first period?
The first menstrual period does not mean that skeletal growth is complete. The specialist uses several maturity indicators to tailor follow-up care.
Sources and medical references
- F09. Assurance Maladie — Definition and causes of scoliosis (in French) — 2 December 2025 · Idiopathic scoliosis and the distinction from postural asymmetry.
- I02. Scoliosis Research Society — Scoliosis, information for parents — Accessed on 11 October 2026 · Causes and common misconceptions.
- F01. HAS — Proposals for individual screening in children aged 7 to 18 (in French) — September 2005, page updated on 30 October 2006 · Scoliosis section; appendix 2.
- F06. Assurance Maladie — Scoliosis: screening, symptoms, diagnosis and progression (in French) — 11 September 2025 · Screening; diagnosis; progression.
- F05. Reference Centre for Vertebral and Spinal Cord Malformations — PNDS: Early spinal deformities (in French) — September 2022 · §3.4.2, p.7, and management; document hosted but not validated by HAS.
- E11. Deschênes S et al. Diagnostic imaging of spinal deformities: reducing patients radiation dose with a new slot-scanning X-ray imager. Spine. 2010;35:989–994..
- E09. Sanders JO et al. Predicting scoliosis progression from skeletal maturity: a simplified classification during adolescence. J Bone Joint Surg Am. 2008;90:540–553..
- E10. Dolan LA et al. BrAIST-Calc: Prediction of Individualized Benefit from Bracing for Adolescent Idiopathic Scoliosis. Spine. 2024;49:147–156..