Clin Orthop Surg.  2018 Dec;10(4):500-507. 10.4055/cios.2018.10.4.500.

Reliability of the EOS Imaging System for Assessment of the Spinal and Pelvic Alignment in the Sagittal Plane

• Kim SB
• Heo YM
• Hwang CM
• Kim TG
• Hong JY
• Won YG
• Ham CU
• Min YK
• Yi JW

• KMID: 2426537
• DOI: http://doi.org/10.4055/cios.2018.10.4.500

Abstract

BACKGROUND
The sagittal alignment of the spine and pelvis is not only closely related to the overall posture of the body but also to the evaluation and treatment of spine disease. In the last few years, the EOS imaging system, a new low-dose radiation X-ray device, became available for sagittal alignment assessment. However, there has been little research on the reliability of EOS. The purpose of this study was to evaluate the intrarater and interrater reliability of EOS for the sagittal alignment assessment of the spine and pelvis.
METHODS
Records of 46 patients were selected from the EOS recording system between November 2016 and April 2017. The exclusion criteria were congenital spinal anomaly and deformity, and previous history of spine and pelvis operation. Sagittal parameters of the spine and pelvis were measured by three examiners three times each using both manual and EOS methods. Means comparison t-test, Pearson bivariate correlation analysis, and reliability analysis by intraclass correlation coefficients (ICCs) for intrarater and interrater reliability were performed using R package "irr."
RESULTS
We found excellent intrarater and interrater reliability of EOS measurements. For intrarater reliability, the ICC ranged from 0.898 to 0.982. For interrater reliability, the ICC ranged from 0.794 to 0.837. We used a paired t-test to compare the values measured by manual and EOS methods: there was no statistically significant difference between the two methods. Correlation analysis also showed a statistically significant positive correlation.
CONCLUSIONS
EOS showed excellent reliability for assessment of the sagittal alignment of the spine and pelvis.

Keyword

Pelvis; Whole body imaging; Reproducibility of results; Postural balance

MeSH Terms

Congenital Abnormalities
Humans
Pelvis
Postural Balance
Posture
Reproducibility of Results
Spine
Whole Body Imaging

Figure

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  Fig. 1 Distortion caused by conical projection from the center to the edges of radiograph, which increases the scale of error for structures farther from the central region.

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  Fig. 2 EOS system cabin to scan the patient in a standing position in two orthogonal planes.

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  Fig. 3 In EOS, when a low-dose X-ray beam passes through the subject and Charpak's chamber, the flow of photons increases in the chamber, amplifying the low-dose X-rays.

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  Fig. 4 The following eight items were measured using the EOS imaging system: pelvic incidence (PI), sacral slope (SS), sagittal pelvic tilt (PT), sagittal vertical axis (SVA), T1/T12 and T4/T12 kyphosis, and L1/S1 and L1/L5 lordosis.

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