Validity of Cobb angle measurements using digitally photographed radiographs

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 degrees 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 degrees 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. (C) 2011 Elsevier Inc. All rights reserved.