Moiré topography in scoliosis screening.

Moiré topography, a simple technique for three-dimensional quantitation, was used to provide interference fringe photographs of the human back with sufficient accuracy to be used for detecting children with asymmetry due to scoliosis. Experimental equipment, built and tested at the National Research Council of Canada, was used in a pilot screening program, involving 1100 children from the 10 to 12 year age group. Each child was examined clinically by the bending test and photographed by the moiré method. All subjects with positive bending tests, asymmetrical fringe patterns or both were submitted to radiographic examination and the results correlated. The moiré technique disclosed 94% of the cases which were found to be positive by X-ray examination, while the bending test disclosed only 46%. The percentages of false positive results were approximately the same for the 2 screening methods.