Validity of Cobb angle measurements using digitally photographed radiographs

Abstract 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.