Validity of Cobb angle measurements using digitally photographed radiographs

Spine J. 2011 Oct;11(10):942-6. doi: 10.1016/j.spinee.2011.09.003.


Background context: Advances in technology are influencing the way that medical information is archived and shared. Considering that an estimated two-thirds of the world has little or no orthopedic care, high demand exists for adequate consultation regarding diagnostic images in orthopedic specialties.

Purpose: To validate the use of photographed scoliosis films for the accurate interpretation of Cobb angles.

Study design: Retrospective review.

Patient sample: Thirty scoliosis radiographs.

Outcome measure: Cobb angle.

Methods: Thirty scoliosis radiographs were photographed using a digital camera from a straight and a 45° angle position. Cobb angles were then measured on the digital images using standard measurement software. Comparison was made between two types of curves: convex and concave, relative to the left side (side for the angled position).

Results: There was excellent reproducibility between the measurements of the conventional radiographs and the photographs taken from a straight on position, p value of .97 for convex curves and p value of .98 for concave curves. Photographs taken from a 45° angle significantly increased the magnitude of the curve convex to the angle (p=.001).

Conclusion: Sharing photographs of scoliosis radiographs can be done with reliability if the image is taken directly in front of the viewbox rather than at an oblique angle; pictures taken at oblique angles are prone to misinterpretation of curve magnitude.

Publication types

  • Validation Study

MeSH terms

  • Humans
  • Lumbar Vertebrae / diagnostic imaging*
  • Radiographic Image Enhancement / methods*
  • Reproducibility of Results
  • Retrospective Studies
  • Scoliosis / diagnostic imaging*
  • Thoracic Vertebrae / diagnostic imaging*