The Cobb angle as an objective measure is used to determine the progression of deformity, and is the basis in the planning of conservative and surgical treatment. However, studies have shown that the Cobb angle has two limitations: an inter- and intraobserver variability of the measurement is approximately 3–5 degrees, and high variability regarding the definition of the end vertebra. Scoliosis is a three-dimensional (3D) pathology, and 3D pathologies cannot be completely assessed by two-dimensional (2D) methods, like 2D radiography. The objective of this study was to determine the intraobserver and interobserver reliability of end vertebra definition and Cobb angle measurement using X-rays and 3D computer tomography (CT) reconstructions in scoliotic spines.
To assess interoberver variation the Cobb angle and the end vertebra were assessed by five observers in 55 patients using X-rays and 3D CT reconstructions. Definition of end vertebra and measurement of the Cobb angle was repeated two times with a three-week interval. Intraclass correlation coefficients (ICC) were used to determine the interobserver and intraobserver reliabilities. 95% prediction limits were provided for measurement errors.
Intraclass correlation coefficient (ICC) showed excellent reliability for both methods. The measured Cobb angle was on average 9.2 degrees larger in the 3D CT group (72.8°, range 30–144) than on 2D radiography (63.6°, range 24–152).
In scoliosis treatment it is very essential to determine the curve magnitude, which is larger in a 3D measurement compared to 2D radiography.
Colwell HR (1990) Radiographic measurements and clinical decisions. J Bone Joint Surg Am 72(3):319 CrossRef
Cobb JR (1948) Outlines for the study of scoliosis. Instr Course Lect 5:261–275
Gross C, Gross M, Kuschner S (1983) Error analysis of scoliosis curvature measurement. Bull Hosp Jt Dis Orthop Inst 43(2):171–177 PubMed
Potter BK, Rosner MK, Lehman RA Jr, Polly DW Jr, Schroeder TM, Kuklo TR (2005) Reliability of end, neutral, and stable vertebrae identification in adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 30(14):1658–1663 CrossRef
Villemure I, Aubin CE, Grimard G, Dansereau J, Labelle H (2001) Progression of vertebral and spinal three-dimensional deformities in adolescent idiopathic scoliosis: a longitudinal study. Spine (Phila Pa 1976) 26(20):2244–2250 CrossRef
DeJonge T, Dubousset JF, Illes T (2002) Hyperrotatory paradoxic kyphosis. Spine 27(4):393–398 CrossRef
Stagnara P (1981) Surgical treatment of kyphotic scoliosis in the adult. Acta Orthop Belg 47(4-5):721–739 PubMed
Adam CJ, Izatt MT, Harvey JR, Askin GN (2005) Variability in Cobb angle measurements using reformatted computerized tomography scans. Spine (Phila Pa 1976) 30(14):1664–1669 CrossRef
Schick D (2004) Computed tomography radiation doses for pediatric scoliosis scans. Internal report commissioned by Pediatric Spine Research Group from Queensland Health Biomedical Technology Services, Australia
Mok JM, Berven SH, Diab M, Hackbarth M, Hu SS, Deviren V (2008) Comparison of observer variation in conventional and three digital radiographic methods used in the evaluation of patients with adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 33(6):681–686. doi: 10.1097/BRS.0b013e318166aa8dCrossRef
Torell G, Nachemson A, Haderspeck-Grib K, Schultz A (1985) Standing and supine Cobb measures in girls with idiopathic scoliosis. Spine (Phila Pa 1976) 10(5):425–427 CrossRef
Yazici M, Acaroglu ER, Alanay A, Deviren V, Cila A, Surat A (2001) Measurement of vertebral rotation in standing versus supine position in adolescent idiopathic scoliosis. J Pediatr Orthop 21(2):252–256 PubMed
- Comparison of two- and three-dimensional measurement of the Cobb angle in scoliosis
- Springer Berlin Heidelberg
Neu im Fachgebiet Orthopädie und Unfallchirurgie
e.Med Kampagnen-Visual, Mail Icon II