What the Cobb Angle Means in Scoliosis

If you’ve ever been told you have scoliosis, you’ve probably heard your doctor mention something called the Cobb angle.

The Cobb angle is the main way doctors measure the severity of scoliosis on an X-ray.

How it’s measured:

1. Doctors identify the most tilted vertebra at the top and bottom of the curve.

2. Lines are drawn along those vertebrae.

3. The angle where the lines intersect is the Cobb angle.

General severity ranges:

• Mild scoliosis: <20°

• Moderate scoliosis: 20–40°

• Severe scoliosis: >40–45°

The Cobb angle helps guide treatment decisions. For example:

• Mild curves are often monitored.

• Moderate curves may be braced (especially in growing adolescents).

• Larger curves may require surgical evaluation.

Curves can occur in different regions of the spine such as thoracic (upper back) or lumbar (lower back), and some people have S-shaped curves with two angles measured.

If you’re comfortable sharing, what was your Cobb angle when you were diagnosed?

References:

Scoliosis Research Society; American Academy of Orthopaedic Surgeons (OrthoInfo); National Institute of Arthritis and Musculoskeletal and Skin Diseases.