JE Lonstein

LG Lenke

M Siljander

MA Asher

P Knott

RJ Cummings

RT Morrissy

S Mardjetko

S Thompson

Scoliosis

English

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The effect of patient positioning during radiographs on the resulting Cobb angle measurements

ORAL PRESENTATION Open Access
The effect of patient positioning during
radiographs on the resulting Cobb angle
measurements
M Siljander1*, P Knott1, S Thompson2, S Mardjetko2
From 8th International Conference on Conservative Management of Spinal Deformities and SOSORT 2011
Annual Meeting
Barcelona, Spain. 19-21 May 2011
Background
Standing spinal radiographs have been the primary
method of spinal deformity evaluation in patients with
scoliosis. During periods of patient surveillance, the clin-
ician compares radiographs over a period of time to
assess the progression of the deformity [1-3]. One of the
potential problems in comparing one radiograph to
another is difference in positioning [4-6]. The goal of
this study is to quantify the effect of trunk rotation on
Cobb angle measurements, and provide an algorithm to
describe this relationship.
Material and methods
CT scans of three patients with Adolescent Idiopathic Sco-
liosis were used retrospectively. Three-dimensional recon-
structions of the images were created by CT scan software.
Cobb angles were drawn for scoliosis curves in the anterior
plane. The 3-D image was then rotated two degrees to the
right, and Cobb angle measurements were repeated. This
procedure was repeated through 14 degrees of right rota-
tion, and then subsequently through 14 degrees of left
rotation.
Results
The effect of trunk rotation on Cobb angle measure-
ments is directly related to the location of the scoliosis
curves, the magnitude of those curves, and the magnitude
of lumbar lordosis and thoracic kyphosis. In general how-
ever, a two degree rotation of the patient’s trunk while
positioning results in a one degree change in the
measured Cobb angle (in patients with larger scoliosis
curves, and in the first six degrees of trunk rotation).
Conclusions
Patient positioning can have a significant effect on the
calculation of scoliosis measurements, and this needs to
be considered when evaluating the progression of spinal
deformity.
Author details
1Rosalind Franklin University North Chicago, USA. 2Illinois Bone and Joint
Institute Morton Grove, USA.
Published: 27 January 2012
References
1. Lonstein JE, Carlson JM: The prediction of curve progression in untreated
idiopathic scoliosis during growth. J Bone Joint Surgery [Am] 1984,
66:1061-71.
2. Screening for adolescent idiopathic scoliosis. Policy statement. US
Preventative Services Task Force. JAMA 1993, 269:2664-6.
3. Asher MA, Burton DC: Adolescent idiopathic scoliosis: natural history and
long term treatment effects. Scoliosis 2006, 1:2, doi: 10.1186/1748-1761-1-2.
4. Cummings RJ, Loveless EA, Campbell J, et al: Interobserver reliability and
intraobserver reproducibility of the system of King et al. for the
classification of adolescent idiopathic scoliosis. J Bone Joint Surg Am 1998,
80(8):1107-11.
5. Lenke LG, Betz RR, Bridwell KH, et al: Intraobserver and interobserver
reliability of the classification of thoracic adolescent idiopathic scoliosis.
J Bone Joint Surg Am 1998, 80(8):1097-106.
6. Morrissy RT, Goldsmith GS, Hall EC, et al: Measurement of the Cobb angle
on radiographs of patients who have scoliosis. Evaluation of intrinsic
error. J Bone Joint Surg Am 1990, 72(3):320-7.
doi:10.1186/1748-7161-7-S1-O12
Cite this article as: Siljander et al.: The effect of patient positioning
during radiographs on the resulting Cobb angle measurements. Scoliosis
2012 7(Suppl 1):O12.
1Rosalind Franklin University North Chicago, USA
Full list of author information is available at the end of the article
Siljander et al. Scoliosis 2012, 7(Suppl 1):O12
http://www.scoliosisjournal.com/content/7/S1/O12
© 2012 Siljander et al; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons
Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in
any medium, provided the original work is properly cited.


Crossref

Carlson JM: The prediction of curve progression in untreated idiopathic scoliosis during growth. J Bone Joint Surgery [Am]

DC: Adolescent idiopathic scoliosis: natural history and long term treatment effects. Scoliosis

Interobserver reliability and intraobserver reproducibility of the system of King et al. for the classification of adolescent idiopathic scoliosis.

Intraobserver and interobserver reliability of the classification of thoracic adolescent idiopathic scoliosis.

Measurement of the Cobb angle on radiographs of patients who have scoliosis. Evaluation of intrinsic error. J Bone Joint Surg Am

Screening for adolescent idiopathic scoliosis. Policy statement. US Preventative Services Task Force. JAMA

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The effect of patient positioning during radiographs on the resulting Cobb angle measurements

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