Measurement accuracy in congenital scoliosis.

Abstract

The accuracy of measurement of curves in idiopathic scoliosis has been extensively studied; however, we know of only one article in the literature concerning the accuracy of measurement of curves in congenital scoliosis. That article stated that intraobserver variability was +/- 9.6 degrees and interobserver variability was +/- 11.8 degrees. Sixty-nine curves in fifty patients with congenital scoliosis were measured on two separate occasions by seven different observers with varying experience in curve measurement. Mean intraobserver variance ranged from 1.9 degrees to 5.0 degrees, with an average of 2.8 degrees (95% confidence limit, +/- 3 degrees) for the seven observers. The interobserver variance was 3.35 degrees (95% confidence limit, 7.86 degrees). It is possible to measure curves in congenital scoliosis with much greater accuracy than previously reported. In the clinical situation in which a skilled observer can measure two radiographs at the same time, an accuracy of +/- 3 degrees can be expected 95% of the time.