Measuring procedures to determine the Cobb angle in idiopathic scoliosis: a systematic review

Scoliosis of the vertebral column can be assessed with the Cobb angle (Cobb 1948). This examination is performed manually by measuring the angle on radiographs and is considered the gold standard. However, studies evaluating the reproducibility of this procedure have shown high variability in intra- and inter-observer agreement. Because of technical advancements, interests in new procedures to determine the Cobb angle has been renewed. This review aims to systematically investigate the reproducibility of various new techniques to determine the Cobb angle in idiopathic scoliosis and to assess whether new technical procedures are reasonable alternatives when compared to manual measurement of the Cobb angle.

Systematic review. Studies examining procedures used to determine the Cobb angle were selected. Two review authors independently selected studies for inclusion, extracted data and assessed risk of bias. Statistical results of reliability and agreement were summarised and described.

Eleven studies of new measuring procedures were included, all reporting the reproducibility. The new procedures can be divided into computer-assisted procedures, automatic procedures and smartphone apps.

All investigated measuring procedures showed high degrees of reliability. In general, digital procedures tend to be slightly better than manual ones. For all other measurement procedures (automatic or smartphone), results varied. Studies implementing vertebral pre-selection and observer training achieved better agreement.