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.
KeywordsCobb angle Idiopathic scoliosis Systematic review Reproducibility Measuring methods Computer-assisted measuring
- D2L, D4L, D6L
Digital two, four or six landmarks
Quality Assessment of Diagnostic Accuracy Studies
Quality Appraisal of Reliability Studies
Standard Error of Measurement
Mean Absolute Difference
Conflict of interest
- 1.Cobb JR (1948) Outline for the study of scoliosis. Am Acad Orthop Surg Instr Course Lect 5:261–275Google Scholar
- 20.Streiner DL, Norman GR (2008) Health measurement scales a practical guide to their development and use, vol 4. Oxford University Press, OxfordGoogle Scholar
- 21.Whiting P, Rutjes AW, Dinnes J, Reitsma J, Bossuyt PM, Kleijnen J (2004) Development and validation of methods for assessing the quality of diagnostic accuracy studies. Health Technol Assess 8(25):1–234 (pii: 98-27-99)Google Scholar