Moiré topography in scoliosis. Correlations with vertebral lateral curvature as determined by radiography.

The backs of 42 subjects were examined using moire topography; 22 of these subjects had scoliosis (range of lateral curvature, 6 degrees-95 degrees; mean, 31 degrees) and had recent radiographs of the spine. Two experienced observers, each an orthopedic surgeon, determined moire angles and number of fringe deviations for each subject. Two radiologists assessed radiographic Cobb angles for each scoliotic subject. For major curves superior to T10 (n = 9), significant correlations were found between Cobb angles and fringe deviations in the W1 region (r = .64, p less than .05). Cobb and moire angles were correlated in the upper O1 region (r = .60, p less than .05) and in the lower O1 region (r = .78, p less than .01). For major curves at or inferior to T10 (n = 13), the angles were correlated in the W region (r = .57, p less than .05). After one hour of training, three physical therapists averaged 87% accuracy in analyzing moire fringe deviations. Complex moire patterns, as observed in obese subjects or those with severe curvature, made fringe-deviation analysis unreliable. The most accurate moire data were obtained at the approximate level of the apex of the scoliotic curve.