A comparison of the reliability and vulnerability of 3D sterEOS and 2D EOS when measuring the sagittal spinal alignment of patients with adolescent idiopathic scoliosis.

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An essential component of making the diagnosis of adolescent idiopathic scoliosis (AIS) is standing anteroposterior and lateral radiographs. Two-dimensional (2D) radiographs inevitably fail to reflect every plane of the three-dimensional (3D) deformity in scoliosis. We have tested the hypothesis that there is no difference in the assessment of the sagittal plane deformity when measured with either 2D or 3D EOS radiography.


A retrospective radiographic analysis was performed on patients diagnosed with AIS, with subdivided into three groups according to the coronal angular deformity (mild group: 45°-69°, moderate group: 70°-89°, and severe group: 90° +). The sagittal parameters were compared between manual measurement with 2D sterEOS and those made using computer-aided 3D reconstruction.


Fifty-two patients were included in each group. The inter-study reliability when measuring the thoracic Kyphosis (TK) and lumbar lordosis (LL) between the two study modalities was excellent in mild group (ICC: 0.90, 95% CI 0.82 ~ 0.94 and ICC: 0.84, 95% CI 0.74 ~ 0.91), excellent in TK and fair in LL in moderate group (ICC: 0.76, 95% CI 0.61 ~ 0.85 and ICC: 0.70, 95% CI 0.53 ~ 0.81), and fair in TK and LL in severe group, respectively (ICC: 0.74, 95% CI 0.57 ~ 0.84 and ICC: 0.65, 95% CI 0.46 ~ 0.84). A Bland-Altman plot showed proportional bias in TK measurements in each group and LL in moderate group, which means the measured value is underestimated in 2D method when the angle is small.


3D sterEOS is less vulnerable to the influence of coronal plane than 2D EOS in evaluating the sagittal spinal parameters of patients with a coronal deformity exceeding 70°.

Level of evidence: 4





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Machida, Masayoshi, Brett Rocos, Karl Zabjek and David E Lebel (2022). A comparison of the reliability and vulnerability of 3D sterEOS and 2D EOS when measuring the sagittal spinal alignment of patients with adolescent idiopathic scoliosis. Spine deformity, 10(5). pp. 1029–1034. 10.1007/s43390-022-00499-4 Retrieved from https://hdl.handle.net/10161/29690.

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Brett Rocos

Assistant Professor of Orthopaedic Surgery

I joined the team at Duke University Health from London, UK, where I was a Consultant Adult and Paediatric Spine Surgeon at Barts Health NHS Trust and Honorary Consultant Senior Lecturer at Queen Mary University of London. I completed my surgical training in in the South West of the UK and at the University of Toronto, and am fellowship trained in adult spine surgery, paediatric spine surgery, orthopaedic trauma surgery, research and healthcare management.

I am driven to support patients at every stage of their care, from clinic assessment, through surgery to discharge. Making sure that every person, adult, child, family or friend understands what’s wrong, helping them to choose the right treatment for them, and what the recovery will be like is an important priority.

My research activity focusses on finding effective new treatments for spinal disorders and bringing them to patients. Focusing on spinal deformity, I have led investigations in the UK, Canada and the USA, and I sit on the Global AO Knowledge Forum for Deformity and the Research Grants Committee at the Scoliosis Research Society. I have lectured in North America and Europe about the treatment of spine disorders for the Scoliosis Research Society, Global Spine Congress, AO Spine and Eurospine, and I have worked hard to produce research that improves the care for spine patients wherever they live. Lastly, I review for several orthopaedic journals and I am Deputy Editor of the Bone and Joint 360, a leading publication with a global readership.

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