Measuring the Cobb Angle

September 27, 2009, Sylvia Ho, Principal Physiotherapist

One of the most common angle used in the measure of scolisis progression is the Cobb angle. The Cobb angle is the measure the frontal deformation looking from the back to the front (or technically, it measures the deformation of the spine at the coronal plane on the anterior-posterior plane.


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The Cobb angle is measured by finding from the top, the most displaced vertebra and from the bottom, most displaced vertebra. The two lines are drawn parallel from the ends of these two vertebrea. Two perpendicular lines are drawn from these two lines. The angle at where the two perpendicular lines meet is the Cobb angle. (see figure).

Do note that there is some error in measuring the cobb angle. Typically, expect about ± 5 degrees. Even when the measurement is done by the same person, same variation is expected.

The cobb angle does not measure the amount of rotation of the spine in the other two planes (sagittal and transverse planes). As scoliosis is a 3-dimensional deformation of the spine, it is possible for a visible improvement of the overall spine but not the cobb angle.

Reference:

  1. Variation in Cobb angle measurements in scoliosis, Volume 23, Number 7 / October, 1994
  2. Reliability of the Cobb angle index derived by traditional and computer assisted methods., Australas Phys Eng Sci Med. 1989 Mar;12(1):16-23.
  3. scoliosis.coreconcepts.com.sg

Related posts:

  1. Cobb Angle and Scoliosis
  2. What can be done for Scoliosis?
  3. The Myth of Scoliosis Treatments
  4. Q angle and knee pain
  5. Does sitting slouched and slanted cause scoliosis?


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This work by Musculoskeletal Consumer Review is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Singapore License. This article was contributed by Core Concepts - Back and Neck Pain Specialists. In the spirit of promoting health education, you may copy, distribute and transmit the work under the conditions specified by the license. For articles re-printed with permission, copyright remains with the original copyright holder (author or publisher). MCR's Creative Commons License does not apply in such cases.


Filed Under Spinal Conditions 

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