Cobb angle

The Cobb angle is a radiographic measurement of a spinal curve, expressed in degrees. For scoliosis it uses the end vertebrae of the curve on an appropriate frontal image. The measurement helps monitoring but does not describe the entire three-dimensional deformity.

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Meaning on imaging

To measure scoliosis, lines are drawn along the endplates of the most tilted vertebrae at the ends of the curve. The angle between their directions gives the Cobb measurement. This frontal measurement describes part of a deformity that can also involve rotation and changes in the sagittal plane.

Indications and assessment

Assessment generally uses appropriate radiographs, often obtained while standing. The clinician also considers age, remaining growth, balance and symptom progression. Decisions about observation, bracing or surgery depend on more than an isolated number and belong within an appropriate specialist care pathway. A measurement is one component of that discussion.

Limitations and interpretation

Posture, selection of the end vertebrae and the reader can change the result by a few degrees. A small difference between examinations does not necessarily mean progression. Comparison is more useful with a consistent method, and repeat radiographs should address a clinical monitoring need rather than be obtained automatically.

Role of TAGMED care

At TAGMED, a known curve can inform goals for comfort and physical function. Traction or another treatment should not be presented as guaranteeing correction of the angle. A progressive curve, particularly during growth, merits specialist follow-up. Changes in symptoms or function should be discussed even when the measured angle is stable.

Frequently asked questions

Does the angle measure pain?

No. It describes a curve, while pain requires a separate assessment.

Do just a few degrees define scoliosis?

A frontal curve of at least 10 degrees is the usual radiographic threshold.

Can it be measured from a back photograph?

No. An external photograph cannot replace radiographic measurement of the vertebrae.

Does a three-degree difference prove worsening?

Not necessarily. Measurement variability needs to be considered before concluding that the curve progressed.

Is an X-ray needed at every visit?

No. Timing depends on progression risk and whether imaging would be clinically useful.

Educational information from The Spine Page. This entry does not replace an individual assessment. Documentary version: October 12, 2026. Sylvain Desforges, B.Sc., D.O., N.D., osteopath and naturopath.