A Comparison of Reliability in Measuring Spinal Curvature

Main Article Content

Apichaya Kiertubonpaiboon
Waranyu Wongseree
Wimol San-Um
Adisorn Leelasantitham
Supaporn Kiattisin


The purpose in this study is to assess intra-rater and inter-rater reliability of 3 methods for measuring spinal curvature in 30 anteroposterior radiograph 2D view (AP view) with spinal patients of Lerdsin hospital during the year from 2004 to 2011. Three methods i.e. Cobb, Ferguson and Polynomial are compared with each value in terms of reliability. Ferguson is the traditional method and Cobb is probably the most popular, while polynomial is one of the first documented mathematical models for sagittal spinal curvature. Intraclass correlation coefficient (ICC) is used to calculate the inter-rater reliability (ICC model 2, 1) and intra-rater reliability (ICC model 3, 1). The statistical analysis shows that the intra-rater reliabilities of Ferguson, Cobb and Polynomial are 0.968, 0.950 and 0.910, respectively. In similarity, their inter-rater reliabilities are 0.477, 0.659 and 0.407 respectively. The results indicate that the most reliable measurement of spinal curvature is the Ferguson method. It can be used to assess the measurement with some cautions especially. And the most reliable measurement of spinal curvature is Cobb method, when using between examiners.


Download data is not yet available.

Article Details

Research Article


J. Dickson and W. Erwin, S. Esses: Spinal Deformity, In S. Esses, ed. “Textbook of Spinal Disorders,” Philadelphia: J.B. Lippincott Company, 1995.

L. Lenke, ”Posterior and Posterolateral Approaches to Spine,” In: K. Bridwell, R. DeWald editors, The Textbook of Spinal Surgery, 2nd ed Philadelphia: Lippincott-Raven: 193, 1997.

P. Pouletaut, H. Dalqamoni, F. Marin, and M.-C. Ho Ba Thoa, “Influence of age, gender and weight on spinal osteoarthritis in the elderly: An analysis of morphometric changes using X-ray images,” IRBM Journal, vol. 31, pp. 141–147, 2010.

R. PuntumetaKul, P. Hiruntrakul, W. Premchaisawat, M. Puntumetakul, and Y. Thavornpitak, “The measurement of lumbar spinal curvature in normal Thai population aged 20-69 years using flexible ruler,” J Med Tech Phy Ther, vol. 24(3), pp. 309-317, Sep. 2012.

T. Thaweewannakij, S. Wongsa, W. Kamruecha, J. Khaengkhan, J. Wongkuanklom, C. Konkamtan, and S. Amatachaya, “Validity and discriminative ability on physical impairment relating to kyphosis using 1.7-cm block,” KKU Res. Journal, vol. 17(4), pp. 660-670, 2012.

M. Gstoettner, K. Sekyra, N. Walochnik, P. Winter, R. Wachter, and C. M. Bach, “Inter and intra-observer reliability assessment of the cobb angle: manual versus digital measurement tools,” Eur Spine Journal, vol. 16(10), pp. 1587–1592, 2007.

D. Lee, S. Antani, Y. Chang, K. Gledhill, L. Rodney Long, and P. Christensen, “CBIR of spine X-ray images on inter-vertebral disc space and shapeprofiles using feature ranking and voting consensus,” Data & Knowledge Engineering, vol. 68, pp. 1359–1369, 2009.

T. Vrtovec, F. Pernus, and B. Likar, “A review of methods for quantitative evaluation of spinal curvature,” Eur Spine Journal, vol. 18, pp. 593–607, 2009.

A. C. Kittleson and L. W. LIM, “Measurement of scoliosis,” American Journal of Roentgenology, vol. 108, pp. 775-777, 1970.

A. Ferguson, “The study and treatment of scoliosis,” South Med Journal, vol. 23, pp. 116–120, 1930.