Measurement accuracy in congenital scoliosis

Background: 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° and interobserver variability was ±11.8°. Methods: 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. Results: Mean intraobserver variance ranged from 1.9° to 5.0°, with an average of 2.8° (95% confidence limit, ±3°) for the seven observers. The interobserver variance was 3.35° (95% confidence limit, 7.86°). Conclusions: 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° can be expected 95% of the time.