Change in Pelvic Sagittal Parameters with Growth in Children with Adolescent Scoliosis

Abstract

Introduction Commonly measured spinopelvic parameters (pelvic incidence, sacral slope, and pelvic tilt) have an effect on global sagittal balance of the spine. It was shown previously by cross-sectional studies that pelvic incidence increases with growth in children. But this change was not demonstrated in longitudinal radiological follow-up studies. In this study, we aimed to investigate the changes in spinopelvic parameters with growth in surgically treated AIS patients. Methods Whole body lateral radiographs eligible for spinopelvic measurements with radiological follow-up before and after skeletal maturity of AIS patients treated surgically were evaluated. First evaluations are made on preoperative radiographs of AIS patients (Risser O or 1). Second evaluations were made on postoperative radiographs taken after skeletal maturity (Risser 5). On whole body lateral radiographs pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), lumbar lordosis between L1 cranial endplate and S1 endplate (LL), and thoracic kyphosis between cranial endplate of T5 and caudal endplate of T12 (TK) were performed using Centricity DICOM software (General Electric). Measurements were made by two observers. Intra- and interobserver reliabilities were also evaluated by repeat measurements. Intra- and interobserver reliabilities for measurements were evaluated by intraclass correlation (ICC). Results A total of 171 surgically treated cases for AIS were reviewed. Of them, 33 cases had radiological follow-up data before and after skeletal maturity with lateral X-rays eligible for spinopelvic parameters measurement. Mean interval between evaluations was 7.49 years. Intra- and interobserver reliabilities for measurements were accepted as “good” with ICC values between 0.951 and 0.989. A significant increase in PI and SS was observed before and after skeletal maturity (46.32 ± 11.61 vs. 52.14 ± 11.69 degrees and 38.14 ± 7.57 vs. 43.19 ± 7.46 degrees, respectively). Increase in LL was also statistically significant and correlated with PI (53.38 ± 9.53 vs. 61.92 ± 10.48 degrees). Changes in TK and PT were not significant. Conclusions Results were concordant with previous cross-sectional and anthropometric studies regarding increase in pelvic incidence by growth. It is also concluded that overall lumbar lordosis is influenced by pelvic incidence both before and after skeletal maturity. As thoracic kyphosis is mainly influenced by instrumentation, no significant difference and relation with spinopelvic parameters were encountered. As reported previously, sagittal profile changes are well tolerated in adolescents, there was no major change in PT. But concerning long fusions, change in pelvic incidence and sacral slope can have a substantial effect on long sagittal profile of surgical candidates.