Do Heavier Patients With Adolescent Idiopathic Scoliosis Have More Preserved Thoracic Kyphosis and Pulmonary Function?

Retrospective.We aimed to determine if heavier patients with adolescent idiopathic scoliosis (AIS) had more preserved thoracic kyphosis (TK), and as a result, more preserved pulmonary function. Some believe that childhood weight is predictive of adult sagittal plane parameters, with heavier children having greater TK as adults. Generally, thoracic scoliosis is coupled with loss of TK, which is associated with worsening pulmonary function.A total of 142 patients with AIS and a structural main thoracic curve were analyzed. We excluded patients with structural proximal thoracic curves (Lenke 2 and 4). Standing preoperative radiographs, pulmonary function tests, and preoperative body mass indices (BMIs) were reviewed. The main thoracic Cobb angle, T2-T12 TK, percentage predicted forced vital capacity (FVC) and BMI were recorded. Spearman correlation was determined. Linear regression analysis used FVC as the primary outcome and BMI, TK, and Cobb angle as the independent variables. BMI categories were overweight/obese (BMI ≥25) and normal (BMI <25). Wilcoxon rank-sum tests were performed to detect a difference in TK and BMI between the 2 groups. The Cobb angles between the two groups were analyzed by t tests.Demonstrated correlations included BMI and FVC (0.37, p ≤.01), FVC and TK (0.26, p <.01), BMI and TK (0.23, p = .01), and FVC and Cobb angle (-0.23, p = .01). Linear regression revealed that Cobb angle (p ≤.01), TK (p <.01), and BMI (p <.01) remained statistically significant predictors of FVC. Wilcoxon rank-sum tests revealed a statistically significant difference between TK (p = .03) and FVC (p <.01) in the overweight/obese group and the normal group, with the overweight/obese group having greater values for both TK and FVC. The Cobb angles between the overweight/obese and normal group were not significantly different (p = .72).Heavier AIS patients have greater values of TK and percentage predicted FVC.Level III.