398 - Reliability of Transverse Plane Parameters for Tridimensional Analysis...

Oral Posters: Cervical

Presented by: V. Lafage - View Audio/Video Presentation (Members Only)

Author(s):

E. Ferrero(1), R. Lafage(2), S. Vira(3), J.H. Oren(3), E.M. Delsole(3), P.-Y. Rohan(4), P. Guigui(1), F.J. Schwab(5), V. Lafage(2), W. Skalli(4)

(1) AP-HP, Paris, France
(2) Hospital for Special Surgery, Spine Research, New York, NY, United States
(3) Hospital for Joint Diseases at NYU Langone Medical Center, Department of Orthopaedic Surgery, New York, NY, United States
(4) Ecole Nationale Supérieure d'Arts et Métiers, Arts et Métiers ParisTech, Paris, France
(5) Hospital for Special Surgery, Spine Service, New York, NY, United States

Abstract

Summary: Tridimensional analysis of adult spinal deformity is essential. Axial vertebral (AVR) and intervertebral rotations (AIR) are of particular interest since disc degeneration is one of the hypotheses of scoliosis genesis. Using ISO standard, 3D analysis was reliable for spinal parameters in entire cohort and was better for axial rotations when Cobb angle was below 30°. 3D reconstructions could help surgeons to anticipate onset of rotatory subluxation and increasing deformity, while assessing AIR and AVR evolution for patients with small deformity.

Hypothesis: Reproducibility is variable depending on curve severity. Design: Reproducibility study with International Standardization Organization (ISO) standard.

Introduction: Beside of sagittal alignment, impact of transverse plane parameters (TPP) and rotatory subluxation on patients reported outcomes was recently highlighted. One of the hypotheses for genesis of degenerative scoliosis is disc degeneration with increased axial vertebral (AVR) and intervertebral rotation (AIR). Therefore, TPP analysis at early stage of the scoliosis seems of particular interest. This study aims at assessing reproducibility of tridimensional (3D) analysis of adult spinal deformity (ASD) patients.

Methods: Thirty ASD patients (Cobb angle > 10°) underwent low-dose biplanar full body radiographs and were divided into 2 groups according to Cobb angle (> 30° or < 30°). Radiographic parameters included: spinal parameters and TPP (apical AVR, AIR of upper and lower level of main curve). Four operators performed the 3D reconstructions 2 times. Intra and inter-observer reliability were analyzed using ISO standard 5725-2, to quantify the global reproducibility standard deviation (SD).

Results: Mean Cobb angle was 31° (mean age 55 years). It was 15° and 44° in groups with Cobb angle < 30° and > 30°. Mean values of apical AVR, upper and lower level AIR of the main curve were respectively 16°±15, 6°±6 and 5°±5. Cobb angle, lordosis and kyphosis Standard Deviation (SD) were below 4.5° and intraclass coefficients of correlation (ICC) above 0.93. ICC of TPP were 0.76, 0.56, 0.39 for respectively AVR, upper AIR, lower AIR. SD of TPP were summarized in table 1.

Conclusion: 3D analysis is reliable for spinal parameters in the entire cohort. Reliability is more accurate for TPP when Cobb angle is below 30°. Lower reliability values for AIR and AVR can be explained by severity of the deformity and bone quality. Nevertheless, 3D reconstructions could help surgeons to anticipate onset of rotatory subluxation while assessing AIR and AVR evolution for patients with small deformity. Once could expect better preoperative standard deviation reproducibility for transverse plane parameters.

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