146 - Reproducibility of Sagittal Radiographic Parameters in Adolescent Idio...

General Session: Pediatric Spine

Presented by: H.W.D. Hey - View Audio/Video Presentation (Members Only)


H.W.D. Hey(1), G.C. Wong(2), C.X. Chan(2), L.L. Lau(1), N. Kumar(1), J.S. Thambiah(1), J.N. Ruiz(1), G.K.P. Liu(1), H.K. Wong(1)

(1) National University Health System, Orthopaedic Surgery, Singapore, Singapore
(2) National University of Singapore, Yong Loo Lin School of Medicine, Singapore, Singapore


Purpose of the Study: Knowledge of sagittal radiographical parameters in Adolescent Idiopathic Scoliosis (AIS) patients has not yet caught up with our understanding of their roles in patients with adult spinal deformity. It is likely that more emphasis will be placed in restoring sagittal parameters for AIS patients in the future. Therefore we need to understand how these parameters may vary in AIS to facilitate management plans. The purpose of this study is to determine the reproducibility of sagittal spinal parameters on lateral film radiographs in patients with AIS. Describe the methods used: This was a retrospective, comparative study conducted in a tertiary healthcare institution from January 2013 to February 2016 (3-year period). All AIS patients who underwent deformity correction surgery from January 2013 to February 2016 and had 2 pre-operative lateral radiographs taken within the time period of a month were included in the study. All patient data was pooled from electronic medical records and X-ray images were retrieved from electronic software. Averaged X-ray measurements by 2 independent assessors were analyzed comparing 2 radiographs of the same patients performed within a 1-month time period. Measured radiographic sagittal spinal parameters include SVA, CL, TK, TL, LL; standard spinopelvic measurements such as PI, PT, SS, as well as end and apical vertebrae of cervical, thoracic and lumbar curves. Chi-squared and Wilcoxon Signed-Rank test was used for categorical and continuous variables. Summarize the

Findings: The study cohort comprised of 138 patients, 28 males and 110 females, with a mean age of 15 years (range 11-20). Between the 2 lateral X-rays, there was a mean difference of 0.79cm in SVA (p< 0.001), 0.70º in LL (p=0.033). and 0.73º in PT (p=0.010). In the combined Lenke 1&2 subgroup, there was a similar 0.77cm (p=0.002), 0.79º (p=0.009) and 1.49º (p=0.001) mean difference in SVA, LL and PT respectively. Additionally, there was also a 1.85º (p=0.009) and 1.76º (p=0.006) mean difference seen in TL and SS respectively. The overall profile of the sagittal curves remained largely similar, with only the lumbar apex shifting from L3 to L4 during the first and the second X-rays respectively (p< 0.001). This occurred for combined Lenke 1&2 subgroup as well (p< 0.001). Include statement of

Conclusions: Most radiographic sagittal spinal parameters in AIS patients are generally reproducible with some variations up to a maximum of 4 degrees. This natural variation should be taken into account when interpreting these radiographic sagittal parameters so as to achieve the most accurate results in surgical planning.