The scoliotic angles of 128 curves in seventy-eight patients were
measured on paired anteroposterior and posteroanterior upright radiographs
that had been made on the same day. The association between the difference
in the measured angles and the various clinical and curve parameters was
examined. The angles on the anteroposterior and posteroanterior radiographs
were highly correlated (r = 0.96). The angles on the posteroanterior
radiographs were larger than those on the anteroposterior radiographs by a
mean of 2.4 degrees for the thoracic curves and 1.7 degrees for the lumbar
curves. Only the thoracolumbar scoliotic angles measured essentially the
same on the two radiographic projections. The magnitude of the difference
between the two measured angles was not correlated with the age of the
patient, the direction of the curve, the magnitude of the curve, or the
degree of deformity in the sagittal plane.