A COMPARISON OF RADIOGRAPHIC AND ELECTROGONIOMETRIC ANGLES IN ADOLESCENT IDIOPATHIC SCOLIOSIS

Study Design. This was a cross-sectional study of a consecutive group of adolescent patients presenting to a scoliosis clinic for routine as sessment or monitoring of their scoliosis, excluding postsurgical pati ents. Summary of Background Data. In vitro studies suggested electrogo niometry could be useful in the evaluation of scoliosis. No prior in v itro study had been performed. Objectives. To determine the reliabilit y and validity of an electrogoniometric instrument, the Metrecom Skele tal Analysis System, in assessing adolescent idiopathic scoliosis. Met hods. Thirty-one patients were examined, radiographed, and scanned wit h the Metrecom Skeletal Analysis System twice by two different examine rs. The magnitudes of the curves derived from the Metrecom Skeletal An alysis System scans were compared with each other and with the Cobb an gles measured from standing radiographs. Results. The intraclass corre lation coefficient (a measure of agreement, ranging fro 0 to 1, where 1 represents complete agreement) for the intraexaminer reliability of the Metrecom Skeletal Analysis System ranged from 0.71 to 0.83. The in terexaminer reliability intraclass correlation coefficient of the Metr ecom Skeletal Analysis System was 0.58, with a mean difference between examiners of 5.5 degrees (SD = 5 degrees), and limits of agreement (m ean difference +/-2 SD) ranging from -4.5 degrees to 15.6 degrees. The Metrecom Skeletal Analysis System and the radiographically derived Co bb angle correlation was 0.64, but the mean difference between the met hods was 3.7 degrees (SD = 11.1), with limits of agreement from 18.4 d egrees to 25.9 degrees. Conclusion. The Metrecom Skeletal Analysis Sys tem does not provide sufficient clinical precision to substitute for t he Cobb angle measured from spinal radiographic measurements in the ma nagement of adolescents with scoliosis.