Presentation of Adolescent Idiopathic Scoliosis: The Bigger the Kid, the Bigger the Curve.

Background: It is our clinical suspicion that children with higher body mass index (BMIs) who are diagnosed with scoliosis tend to have larger curves on presentation. The purpose of this study was to determine the effect of BMI on severity of curve at initial presentation of adolescent idiopathic scoliosis.

Methods: This is a retrospective, descriptive cohort study of consecutive patients age 10 or greater referred to a single large tertiary care center with concern for spinal asymmetry. Patients were separated into 3 BMI categories as measured on the presenting visit: normal weight-≥5th and <85th percentile, overweight-≥85th and <95th percentile, and obese-≥95th percentile. In addition to demographic information, data collected included BMI, curve magnitude, curve location, Risser stage, and where or by whom spinal asymmetry was noted.

Results: A total of 150 patients, 50 in each the normal weight, overweight, and obese categories, were included in this study. Average curve at presentation for normal weight patients was 18.1 degrees, for overweight patients 23.9 degrees (P=0.02), and for obese patients 24.5 degrees (P=0.02). As compared with the normal weight group, odds ratio of presenting with a curve of 40 degrees or above was 10.8 for the overweight group (95% confidence interval, 1.3-88.5, P=0.03) and 12.2 for the obese group (95% confidence interval, 1.5-99.8, P=0.02). Assuming a cut-off of 45 degrees as surgical range, no normal weight patients presented in surgical range (0%), but 7/50 (14%, P=0.01) overweight and 8/50 (16%, P<0.01) obese patients did. Moreover, higher BMI patients were significantly more likely to present at a higher degree of skeletally maturity, with an average Risser of 1.8 for normal weight patients, 2.7 (P=0.01) for overweight patients, and 2.9 (P=0.01) for obese patients.

Conclusions: Overweight and obese patients with adolescent idiopathic scoliosis present at significantly larger curve magnitudes and significantly higher degrees of skeletal maturity. Moreover, these patients were significantly more likely to present with very large curves and, in our study, all patients presenting with a surgical range curve were either overweight or obese.

Level Of Evidence: Level III-Retrospective case-control.