Reliability of novice physiotherapists for measuring Cobb angle using a digital method

Abstract

Background: The Cobb’s method is the most accurate and reliable method for kyphosis measurement. Conventionally, a sagittal Cobb angle was commonly derived from a lateral plain film. With computer technology, a digital method is widely used in common clinical settings, but the existing reliability data involved only experienced raters. Objectives: To assess the interrater and intrarater reliability of a digital Cobb’s method using novice physiotherapists. Methods: Fifteen participants, with an occiput wall distance of more than 0 cm, were interviewed and assessed for their demographics. Then they were filmed for lateral spinal radiography over the area of thoracic spine in a standing position, and the Cobb angle was analyzed by four raters, including an expert physician and three novice physiotherapists, using a SurgimapSpine programme. Results: The average Cobb angles among the four raters showed no significant difference (p=0.984). Outcomes of their measurements had excellent intrarater and interrater reliability [intraclass correlation coefficient (ICC3,3)=0.995–0.997] with a small range of standard errors of the measurement (<1°). Conclusion: A digital Cobb’s method had excellent reliability when used by a novice health professional rater. The findings confirm the ease of using this method to detect and monitor kyphosis in general hospitals, clinics, or research facilities. Keywords: Cobb angle, spinal angle, reliability, spinal deformity, X-ray