Difference in whole spinal alignment between supine and standing positions in patients with adult spinal deformity using a new comparison method with slot-scanning three-dimensional X-ray imager and computed tomography through digital reconstructed radiography

Abstract Background A precise comparison of supine and standing whole spine alignment in both the coronal and sagittal planes, including the pelvic parameters, has not been reported. Furthermore, previous studies investigated positional differences in the Cobb angle only in young patients with idiopathic scoliosis. The difference in alignment has never been investigated in a population of patients with adult spinal deformity (ASD). In most cases, ASD patients are aware of the symptoms when standing and tend to stoop with back pain, whereas the symptoms disappear when lying on a bed. Therefore, it is important to elucidate the positional differences in the deformity in older adults. The purposes of this study are to establish a method for comparing whole spine alignment between supine and standing, and to clarify the positional difference of the alignment in the patients with ASD. Methods Twenty-four patients with ASD (mean age: 60.1 years, range 20–80 years; 24 women) were evaluated. A slot-scanning three-dimensional X-ray imager (EOS) was used to assess the whole spine in the standing position. Computed tomography was used to assess the whole spine in the supine position. The computed tomography DICOM dataset of the whole spine in the supine position was transformed to two-dimensional (coronal and sagittal) digital reconstructed radiography images. The digital reconstructed radiography images were input for three-dimensional measurement by the EOS software and compared with the standing whole spine alignment measured by EOS. Results The mean intraclass correlation coefficients (supine, standing) of intra-rater / inter-rater reliabilities for the measured parameters were 0.981, 0.984 / 0.970, 0.986, respectively. The Cobb and rotation angles of the major curve, mostly the thoracolumbar area, were significantly greater in the standing position than in the supine position. Lumbar lordosis during standing was significantly kyphotic. With respect to the pelvic parameters, the sacral slope was significantly smaller in the standing position than in the supine position. Pelvic tilt and pelvic incidence were significantly greater in the standing position than in the supine position. Conclusions The lumbar to pelvic parameters and the major curve in standing position significantly deteriorate compared with the supine position in patients with ASD

Anatomical Pelvic Parameters Using the Anterior Pelvic Plane: Normative Values and Estimation of the Standing Sagittal Alignment in Healthy Volunteers

Introduction: In this study, we aim to estimate the natural standing sagittal alignment in patients with adult spinal deformity (ASD), firstly by investigating the normative values of anatomical pelvic parameters based on the anterior pelvic plane (APP) in a healthy population, and to clarify the relationships between the anatomical and positional pelvic parameters in standing position. Methods: The images of biplanar slot-scanning full-body stereoradiography in 140 healthy Japanese volunteers (mean age, 39.5 years; 59.3% female) were examined. In addition to three-dimensional measurements including pelvic incidence (PI), sacral slope (SS), and pelvic tilt (PT), the APP angle (APPA; anterior tilting=positive) was measured as the angle between the APP and the vertical line using the two-dimensional lateral image. Anatomical SS and PT (aSS and aPT) were calculated as the angles of SS and PT in reference to APP. Results: The mean (range) values of APPA, aSS, and aPT were determined to be 0.7° (−16.8°/15.5°), 36.8° (18.3°/64.9°), and 13.2° (−0.6°/28.7°), respectively. Moreover, SS was found to be significantly correlated with PI and aSS, while PT was significantly correlated with PI, aSS, aPT, and body weight. Also, PT was significantly larger in females than in males. Multiple linear regression analysis deduced the following equations: SS=0.404×aSS+0.203×PI+12.463, PT=−0.391×aSS+0.774×PI+1.950×sex (male=0, female=1)−12.971, wherein aSS had the greatest effect for predicting SS among the included factors and PI had the greatest effect for predicting PT. In addition, no significant differences were noted between PT/PI and aPT/PI. Conclusions: As per the results of this study, significant correlations were noted among parameters and predicting models for positional parameters (SS and PT) using anatomical parameters (aSS and aPT) in a healthy population. This novel measurement concept based on the APP has been considered to be useful in estimating natural SS and PT in standing position using the anatomical pelvic parameters in patients with ASD