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BackgroundThree dimensional (3D) markerless asymmetry analysis was developed to assess and monitor the scoliotic curve. While the developed surface topography (ST) indices demonstrated a strong correlation with the Cobb angle and its change over time, it was reported that the method requires an expert for monitoring the procedure to prevent misclassification for some patients. Therefore, this study aimed at improving the user-independence level of the previously developed 3D markerless asymmetry analysis implementing a new asymmetry threshold without compromising its accuracy in identifying the progressive scoliotic curves.MethodsA retrospective study was conducted on 128 patients with Adolescent Idiopathic Scoliosis (AIS), with baseline and follow-up radiograph and surface topography assessments. The suggested “cut point” which was used to separate the deformed surfaces of the torso from the undeformed regions, automatically generated deviation patches corresponding to scoliotic curves for all analyzed surface topography scans.ResultsBy changing the “cut point” in the asymmetry analysis for monitoring scoliotic curves progression, the sensitivity for identifying curve progression was increased from 68 to 75%, while the specificity was decreased from 74 to 59%, compared with the original method with different “cut point”.ConclusionsThese results lead to a more conservative approach in monitoring of scoliotic curves in clinical applications; smaller number of radiographs would be saved, however the risk of having non-measured curves with progression would be decreased.

IntroductionRecently the EOS imaging system (EOS Imaging, Paris, France) has provided advancements in 3D spinal modeling. Advancements include low radiation as well as fast and accurate reconstructed measurements of spinal parameters. There is a paucity of studies analyzing the reproducibility of the EOS Imaging System and the sterEOS software in the production of 3D spinal models for children with adolescent idiopathic scoliosis (AIS). Objectives The purposes of the study were 1) to determine the intraclass correlation (ICC) for both the inter-observer and intra-observer in the measurements of Cobb angles in AP view as well as the Cobb angles in the lateral view; 2) to assess the ICC for inter-and intra-observer in the axial vertebral rotation (AVR) of the apex vertebra; 3) to compare differences of spinal parameters between two examiners and two trials; 4) to determine how long a 3D reconstruction of the spine takes. Methods Bilateral x-ray images of fifteen patients (age: 6 -15 years old, 5 males, 10 females) were retrospectively selected. These EOS images were uploaded into the sterEOS computer program. Within the software, spinal and pelvic parameters were identified manually to construct a 3D model of the spine. The sterEOS software calculates the Cobb angles, angles of lordosis, angles of kyphosis, and the AVRs of the apex vertebra. The 3D modeling was performed independently by two examiners. Each examiner modeled each patient's spine in two spaced out trials. The ICC between inter-and intra-observers were calculated and compared statistically. Results and discussionBoth the inter-and intra-observers showed excellent reproducibility for the Cobb angles in the proximal segment (ICC: 0.72 -0.91), kyphosis (ICC: 0.85-0.92), and lordosis (ICC: 0.82 -0.95). No significant differences were found between angle differences (0.35°to 2.4°). In contrast to the traditional radiography, the sterEOS provides a better high quality view within the sagittal plane. A moderate inter-observer ICC for the Cobb angle in the distal segment (ICC = 0.67) indicates the examiners have to carefully adjust the alignment and vertebrae in 3D rather than in 2D following the automatic computation from the EOS software. The interobserver ICC for the AVR in the lumbar region (0.80) is higher than the thoracic or thoracolumbar region (0.65), but with high differences of AVR (4.0°-6.3°). The average time that two examiners spent per subject ranged from 34.6 to 37.4 minutes. Conclusion and significance EOS provides significantly reliable and accurate spinal modeling in the measurement of children with AIS. Exposure to less radiation as compared to other radiographic modality allows EOS to offer acceptable quality view of the spine in the sagittal and transversal plane. sagittal balance and predictive equations to determine lumbopelvic compensatory patterns (LPCP). These equations are used to guide surgical decision making and technique selection. Although other lumbopelvic compensation equations are available, these have not been compared wi...

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