Measuring Scoliosis in the Young Versus the Old



Scoliosis (curvature of the spine) can affect young teenagers and older adults but for different reasons. In the young, the condition is often considered idiopathic (of unknown cause). In older adults (age 60 and older), degenerative processes in the spine are the most common cause of scoliosis.

Determining the severity of the curve depends on using X-rays to measure angles. There are two different methods for this: the Cobb method and the centroid method. Each of these methods utilizes lines that form angles on the spinal X-ray. The Cobb method has been the “gold standard” in teenage scoliosis. But in older adults, measuring the angles becomes increasingly difficult as the degenerative changes alter alignment and distort the spinal column.

To determine which method might work best for adult scoliosis, researchers from Korea compared the Cobb method against the centroid method in 60 patients. Three examiners (all were spine surgeons) independently reviewed the X-rays using both methods. They repeated the measurements two times, one week apart.

Inter- and intrarater reliability was measured — meaning how close the results were each time the examiners measured and from one examiner to the others. Accurate measurements are important in planning the most appropriate treatment for each patient.

Using statistical analysis of all the data collected, they were able to determine that there was:

  • Excellent correlation between both methods with both inter- and intraobserver comparisons.
  • Overall, the Cobb method was more reliable than the centroid method of this older age group.
  • The Cobb method was more a more reliable method when measuring more severe scoliosis.

    Other studies show that the centroid method is a more reliable way to measure scoliosis in adolescents. Because of the way centroid measurements are taken, distortions of the vertebra or endplates (present in the older degenerated spine) create too much variability and thus decrease reliability.

    The Cobb method relies on selecting the most appropriate vertebrae to begin and end the measuring process. Degenerative changes causing thicker endplates present in older adults (but not in adolescents) make it easier to determine where to draw the lines that form the angles in the Cobb method of measuring.

    The authors concluded that whereas a previous study they did showed the centroid method to be more reliable with adolescent scoliosis, the Cobb method is a better measuring tool for adult scoliosis. Changes in the vertebrae between young and old with scoliosis are different enough to warrant different methods of measuring the severity.

    There are however, still some contradictory results among various studies. This suggests further investigation of these two methods of measuring scoliosis based on differences in age and characteristics of the scoliosis is needed. Since treatment decisions rely on an accurate measurement of scoliosis severity, finding the most reliable method of measurement is important across the lifespan.