It happens at the beach, or at the pool. You look at him from behind and see something that was not there yesterday: one shoulder is lower than the other. Or a shoulder blade sticks out like a wing, one hip looks fuller, the swimsuit sits crooked on him.
Search engines always throw up the same word.
So here is the answer straight away: the shoulder is the most visible sign and the least reliable one there is. What matters is called the gibbus, it only shows when the teenager bends forward, and in all likelihood you will not find it. True scoliosis, at least 10 degrees Cobb on X-ray, affects between 1% and 4% of adolescents, according to the monograph in Nature Reviews Disease Primers.
Why the shoulder misleads
The height of the shoulders is an unstable measure even for those who measure them for a living.
In a study of 31 adolescents with known scoliosis and average curves of 25 degrees, two trained physiotherapists measured each teenager on the same day. On trunk rotation the agreement was excellent (intraclass correlation 0.92); on the tilt of the shoulders and pelvis it was poor. Same teenager, same morning, and they could not agree about the shoulder.
Add to that the fact that the body is not symmetrical and does not need to be: the hand he uses, the bag he carries, the leg he puts his weight on, growth that comes in spurts. An asymmetry while standing is the norm, not the exception.
The limit: 31 teenagers, all already with a known scoliosis. But the message holds: if you decide by looking at the shoulders, you are deciding on the most unstable measure there is.
The Adams test: how to do it at home, for real
It is the same check the paediatrician does, and it requires nothing.
How to do it. Bare-chested, in a well-lit spot. Feet together and parallel, knees straight (this is the detail that always gets missed and spoils the test), arms hanging free with the hands close together. Then he bends slowly forward, as if to touch his toes, until his back is horizontal.
How to look. You stand behind him and lower your eyes to the level of his back: not from above, but across, the way you would look at the water level in a glass. From there, slowly scan from the neck down to the pelvis.
What to look for. One side of the back higher than the other, a prominence that forms precisely as he bends. That is the gibbus: it is not a bigger muscle, it is the rib cage following the vertebrae as they rotate. Also check the height of the hips, since some curves sit there.
What it means. If the two sides rise equally, you have not found a gibbus. If one is clearly higher, you have found a rotation: the sign of a structural curve. What the test does not tell you is how large the curve is: only an X-ray measures that.
And one necessary honesty: the forward-bending test, on its own, is not an examination. In a school screening of 2,700 teenagers aged 8 to 16 on the island of Samos, where all of them also had an X-ray, the Adams test showed a sensitivity of 84.37% and a specificity of 93.44%: five scolioses out of thirty-two had slipped through. The authors write that as the sole diagnostic criterion it is not safe. Take it for what it is: a rough filter, not a verdict.
Postural asymmetry or structural curve
Postural asymmetry is seen standing and dissolves when the position changes: bending forward, the two sides rise equally. It is very common, it is not a disease and it is not the antechamber to anything.
A structural curve carries a rotation of the vertebrae, and the rotation does not dissolve: the gibbus stays there. That is why the right filter is forward bending, not a glance while standing.
But even when the gibbus is there, the story is not over. In a screening of 33,596 girls from the last year of primary school to the first year of middle school, using a trunk rotation of at least 5 degrees on the scoliometer as the criterion, 5.2% were sent for an X-ray: of these, 28.3% had a curve of at least 10 degrees and only 4% of at least 20.
Read it the other way round: seven girls out of ten with a measurable gibbus had no scoliosis, and more than nine out of ten had nothing to treat. In Samos, where everyone had an X-ray, 5.66% had some deformity of the back but only 1.18% a true scoliosis.
A gibbus is a good reason to have the back looked at by someone who knows how to look at it. It is not a diagnosis.
School screening: what worked and what did not
But don't they check at school? In Italy, no: back checks go through the paediatrician's routine health checks. It is worth knowing, however, how things went where mass screening was done for decades.
In 2018 the US Preventive Services Task Force updated its recommendation on screening for idiopathic scoliosis in asymptomatic young people aged 10 to 18, and the conclusion is an I statement: insufficient evidence to determine the balance of benefits and harms. The review underneath pooled 14 studies and 448,276 people and found that screening works as a test, with the best accuracy, 93.8% sensitivity and 99.2% specificity, coming from a programme of 306,082 young people that combined the forward-bending test, the scoliometer and Moiré topography, and that a brace can slow progression. What it did not find is the decisive piece: no direct evidence that the young people identified by screening do better as adults.
The cost of "finding a lot" shows in a population study in JAMA: 2,242 children checked every year from the last year of primary school to the first year of secondary school and followed up to age 19. 92 (4.1%) were referred for assessment; the children who were eventually treated for scoliosis were 9, and screening had identified 5 of them. Positive predictive value for treated scoliosis: 0.05. It took 448 children to be examined to find one destined for treatment.
This is not an argument against checks: it is the reason why, for twenty years, those who work in the field have proposed changing how they are done. In a 2005 review the same author who proposed the 5-degree threshold calls for objective referral criteria, for borderline cases to be re-checked instead of being sent straight for an X-ray, and for screening to focus on girls not yet mature. In Samos, with stricter criteria, including 8 degrees on the scoliometer, 89.4% of the X-rays would have been avoided; among the 33,596 girls, moving from 5 to 7 degrees brought referrals down from 5.2% to 1.4%, at the price of also missing large curves. A threshold that satisfies everyone does not exist, and the authors say so.
What happens after the diagnosis, Cobb angles, brace, exercises and what the trials have shown, is in Adolescent scoliosis: exercises, brace and what really works.
The gibbus finds it, but growth predicts it
That the gibbus is the right sign for finding a scoliosis is well demonstrated. In a Finnish cohort, 896 children without scoliosis at entry were examined every year from an average age of 10.8 to 13.8: over three years scoliosis appeared in 65 of them, and trunk asymmetry on forward bending was found to be the strongest determinant of incidence (adjusted odds ratio 1.61 per additional millimetre of gibbus, 95% CI: 1.42-1.82).
But once the curve is there, how prominent the gibbus is does not say how much it will worsen. In the historical series of 727 teenagers with initial curves between 5 and 29 degrees left untreated, 23.2% progressed: progression was linked to the size of the curve, the age at the first visit, the Risser sign (a measure of bone maturity read on the pelvis) and menarche. Not to sex, family history or rotational prominence.
The reason is that idiopathic scoliosis gets worse while the bone grows and stops when growth ends: the same 20-degree curve means two different things in an eleven-year-old girl and in a sixteen-year-old with menarche three years earlier. In the Finnish study, the girls who later developed scoliosis had reached their peak trunk growth earlier than the others (11.8 against 12.1 years, P = 0.02); the difference in the velocity of the peak (5.5 against 6.1 cm a year) was not statistically significant, and it is the kind of figure that is usually rounded up.
That small curves move is shown by the ten-year follow-up from Samos: of the 121 deformities under 10 degrees Cobb, 44 (35.8%) progressed by at least 5 degrees; of the 29 curves between 10 and 20 degrees, 14 (48.3%). Progressing by 5 degrees does not mean ending up in the operating theatre: of 2,700 teenagers, over ten years, three wore a brace and one was operated on. But it does mean that during growth the check is repeated, it is not done once.
The practical rule fits on one line: if the shape of the back changes within a few months while your child is growing fast, it is time to have it checked.
When an X-ray is done, and when not
It is done when the clinical examination finds something consistent and the result changes a decision: the X-ray is the only way to measure Cobb angles, and it is the angles that decide whether to observe, whether to work with specific exercises or whether to consider a brace. The threshold most often used for sending someone for one is a trunk rotation of around 5-7 degrees on the scoliometer; the 5-degree threshold comes from a study of 1,065 patients that proposed it to identify curves of at least 20 degrees.
It is not done to confirm an asymmetry that disappears when bending forward, and it is not repeated every few months for reassurance. The dose is not dramatic but it is not zero: an Italian phantom study measured 0.43 mSv with the low-dose EOS system against 0.87 mSv with computed radiography, estimating 5.4 against 9.7 induced cancers per 100,000 people examined (calculation for a twenty-year-old male). And a Danish cohort of 215 teenagers treated 25 years earlier, with an average of 16 X-rays each, reported a relative cancer risk of 4.8 (95% CI: 2.3-5.8) compared with the general population.
That figure should be treated with caution, and we are the ones who say so: 9 cancers in total, a small cohort, partly followed up by questionnaire, made up of teenagers who were treated and therefore much more exposed than someone who has a single X-ray. It does not prove a cause. It is a good reason not to repeat X-rays outside a pathway decided by a doctor; it is not a reason to refuse them when they are needed.
Red flags
Everything you have read applies to the teenager who is well and has only an asymmetry: the screening recommendations, the American one included, refer to adolescents without symptoms. In the cases below, screening no longer applies, and the right place is the doctor.
- Pain that wakes him at night, or that lasts for weeks and gets worse instead of easing. Do not wait for the next check.
- Tingling, loss of strength, a different way of walking, a foot that is deforming or turning: medical assessment in a short time, not "let's see how it goes". And if they appeared within hours or a few days, or difficulty passing urine or holding it is added, go to A&E today.
- A back that twists before the age of 10: it is a different age group, with different causes to investigate.
- Skin markings along the spine: café-au-lait spots, a tuft of hair, a dimple, a haemangioma. They need to be shown to a doctor.
- An obvious change within a few months, or the trunk visibly shifted sideways relative to the pelvis.
- Breathlessness appearing together with the deformity.
The list is not meant to frighten you: it is there to say that not all curves are idiopathic. In 446 patients with thoracolumbar or lumbar curves classified as idiopathic at a spinal surgery centre, MRI found neural axis abnormalities in 7.8%, more frequent in boys, in larger curves and in younger patients. It is a surgical population, highly selected and not comparable to your child: we mention it only because it shows that when the picture is atypical, further investigation exists, and it is the specialist who decides.
If what worries you most is the pain, the line between normal and worth checking is in Back pain in children and adolescents: when to worry.
And the backpack, the sofa, the way he sits?
No. It is the question that always comes up here, with the guilt that comes with it, and the answer remains no: idiopathic scoliosis is called that precisely because its cause is not known. The data on backpacks, desks and posture at school are numerous and consistent, and you will find them in Posture at school and backpacks: what really matters for the back.
What a physiotherapist can do, and what not
First the nos, because they save you time and money. A physiotherapist does not diagnose scoliosis: an X-ray and a specialist are needed. And does not straighten a back with gymnastics: specific exercises have measurable effects on small curves, but they are counted in degrees, not in cures.
The yeses are more concrete than they seem. Looking with you to understand whether that shoulder is a posture or a rotation. Measuring the gibbus and repeating the same measurement over time: on the reliability of the scoliometer the data say something useful, namely that agreement between different examiners is good (0.81-0.82) but the repetition by the same examiner is almost perfect (0.995-0.998). Who measures matters less than measuring the same person with the same method every time. Telling you if and when a doctor is needed. And, in most cases, lifting off you an anxiety that has no reason to be there.
With Ri-Hub Junior you start with a free twenty-minute introductory consultation by video call with a physiotherapist on the Italian professional register who works with children and teenagers: you have him do the forward bend in front of the camera, the physiotherapist looks with you and tells you what they see and what to do next. Up to age 10, sessions last 50 minutes and cost 59,90 €; from 11 to 18 you move to the standard session at 29,90 €.
The limit, stated before rather than after: online you cannot measure with a scoliometer and you cannot make a diagnosis. It serves to understand whether what you saw deserves a specialist or is one of the many asymmetries that mean nothing. If any of the signs in the list above appear, the right place is the doctor, straight away. And complex neurological and neuromuscular conditions require in-person assessment: we do not follow those online.
In three lines
The lower shoulder is the sign that is easiest to see and the least reliable. Have him bend forward and look at the level of the back: if the two sides rise equally, you are done. If one side stays higher, it is a reason to have the back looked at by a professional, not a reason to be afraid: seven teenagers out of ten with a measurable gibbus have no scoliosis. And if there is night pain, a neurological sign or a rapid change, it is no longer screening: it is the doctor, and it does not wait.
Sources
- Adolescent idiopathic scoliosis, Nature Reviews Disease Primers, 2015
- Screening for Adolescent Idiopathic Scoliosis: US Preventive Services Task Force Recommendation Statement, JAMA, 2018
- Screening for Adolescent Idiopathic Scoliosis: Evidence Report and Systematic Review for the US Preventive Services Task Force, JAMA, 2018
- A population-based study of school scoliosis screening, JAMA, 1999
- Ten-year follow-up evaluation of a school screening program for scoliosis. Is the forward-bending test an accurate diagnostic criterion for the screening of scoliosis?, Spine, 1999
- Cut-off point of the Scoliometer in school scoliosis screening, Spine, 1997
- An objective criterion for scoliosis screening, The Journal of Bone and Joint Surgery (American volume), 1984
- Selective screening for scoliosis, Clinical Orthopaedics and Related Research, 2005
- Trunk asymmetry, posture, growth, and risk of scoliosis. A three-year follow-up of Finnish prepubertal school children, Spine, 1993
- The prediction of curve progression in untreated idiopathic scoliosis during growth, The Journal of Bone and Joint Surgery (American volume), 1984
- Reliability and concurrent validity of postural asymmetry measurement in adolescent idiopathic scoliosis, World Journal of Orthopedics, 2017
- An assessment of the reliability of the Scoliometer, Spine, 1993
- Organ doses and lifetime attributable risk evaluations for scoliosis examinations of adolescent patients with the EOS imaging system, La Radiologia Medica, 2018
- Incidence of cancer in adolescent idiopathic scoliosis patients treated 25 years previously, European Spine Journal, 2016
- Indication for preoperative MRI of neural axis abnormalities in patients with presumed thoracolumbar/lumbar idiopathic scoliosis, European Spine Journal, 2013
Last source check: September 2026.
