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Oral presentation | Open | Published:

The reliability and prognostic implications of a simplified bone age classification system for adolescent idiopathic scoliosis


Sanders et al. [1, 2] describe a simplified system for determining digital skeletal age (DSA) and its use in predicting the likelihood a curve will reach surgical magnitude. We assessed the inter-and intra-rater reliability and prognostic implications of this classification system using data from a multicenter trial of outcomes in AIS (BrAIST).

Material and methods

36 subjects were randomly selected. We determined the predicted prognosis by cross-classifying the DSA and Cobb angle using Sanders’ estimates.


Kappa coefficients ranged from 0.76 to 0.88. For example, one rater’s reading corresponded to a 0% risk of the curve reaching surgical magnitude, while the other rater’s reading for the same subject corresponded to a 92% risk.

The high level of agreement in DSA found by Sanders et. al was replicated in this study, and would be considered “substantial” to “almost perfect” using widely applied standards [3] Despite this agreement, different prognoses were predicted for 11% of these subjects.


Clinicians and researchers should consider seeking a second review of the DSA (especially if it appears to be in the DSA 2 to 3 range), and the Cobb angle, prior to using it to make prognostic predictions and treatment decisions.


  1. 1.

    Sanders JO, Browne RH, McConnell SJ: Maturity assessment and curve progression in girls with Idiopathic Scoliosis. J Bone Joint Surg Am. 2007, 89: 64-73.

  2. 2.

    Sanders JO, Khoury JG, Kishan S, Browne RH, Mooney JF, Arnold KD, McConnell SJ, Bauman JA, Finegold DN: Predicting scoliosis progression from skeletal maturity: a simplified classification during adolescence. J Bone Joint Surg Am. 2008, 90 (3): 540-53. 10.2106/JBJS.G.00004.

  3. 3.

    Landis JR, Koch GG: The measurement of observer agreement for categorical data. Biometrics. 1977, 33: 159-74. 10.2307/2529310.

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Correspondence to L Dolan.

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  • Public Health
  • Treatment Decision
  • Classification System
  • Multicenter Trial
  • Adolescent Idiopathic Scoliosis