Spinopelvic assessment is critical for surgical planning. It is unknown if age, sex, and body mass index (BMI) influence pelvic orientation during development. This study aimed to (1) describe normative pelvic orientation and (2) investigate how patient-specific factors pelvic orientation throughout development from childhood to early adulthood. Computed tomography pelvis scans of supine asymptomatic patients were obtained at a single institution from 2004 to 2022. Three-dimensional measurements of pelvic incidence (PI), sacral slope (SS), and pelvic tilt (PT) were measured utilizing a custom-developed software (VirtualHip, Boston Children’s Hospital). Pelvic orientations were modeled as a function of age, sex, and BMI with univariate and multivariable generalized additive models. A total of 9,721 patients (14.2 ± 4.2 years) were included with 49% females (n=4,800), 35.1% skeletally immature (n=3,413) as defined by triradiate cartilage closure, and 18.5% obese patients (n=1,311) as defined by BMI>95 th percentile. Spinopelvic parameters were not static over the course of development. After skeletal maturity, females had slightly higher PI and PT compared to males (<3°, p<0.001). PI trends were not static across age and physeal status. Pubertal patients with an open physis had higher PI by 3-4° as compared to patients with closed physes (p=0.03). Sex and obesity-related differences were small prior to skeletal maturity (<2°,p<0.001). Multivariable analyses revealed skeletally mature females to have differences in sacral slope whereas skeletally mature males to have differences in pelvic tilt by about 2° when obese. Unlike adults, there are no significant variations in spinopelvic balance during development from ages 7 to 25. Based on a large sample size of 9,721 patients, this work establishes normative values for supine spinopelvic balance during skeletal development stratified by sex, age, BMI, and skeletal maturity. Future investigations on the clinical impact of minor variations between groups based on these subgroups may uncover phenotypic predispositions to spine/pelvis pathology. III • Spinopelvic parameters change throughout childhood and adolescence until skeletal maturity however these small differences are not clinically meaningful as they remain within standard errors of radiographic measurements. • Sex and weight related differences in spinopelvic parameters prior to skeletal maturity are minimal (<2°, p<0.001) • After skeletal maturity, females had a trend towards minimally higher PI and PT compared to males (<3°, p<0.001) while obese patients trended towards up to 2° higher SS with no difference in PI or PT (p<0.001). • Patients 12 to 14 years of age with an open triradiate cartilage demonstrated a 3-4° increase in pelvic incidence compared to those with closed physes (p<0.05).
Lavoie-Gagne et al. (Wed,) studied this question.
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