The Sanders Classification and Obesity: Do Obese Kids With AIS Present With More Advanced Skeletal Maturity?

Introduction: Obese and overweight (OOW) patients with adolescent idiopathic scoliosis (AIS) have been shown to initially present with a more advanced Risser score compared to normal weight (NW) patients. The Sanders Maturity Scale (SMS) is now more commonly used by surgeons to assist with treatment decisions because it more reliably predicts skeletal maturity. However, the relationship between SMS and obesity has not been described. We hypothesize that in patients with AIS, OOW patients will have a higher SMS score on initial presentation when compared to NW patients.

Methods: Billing data from 2 different institutions were used to identify patients with AIS presenting to a pediatric orthopaedic spine surgeon for an initial visit between July 2012 and March 2020. We excluded those without height/weight data, spine radiographs, or left-hand radiographs for measuring SMS stage. Body mass index-for-age percentiles were calculated and used to group patients into NW (<85th percentile) or OOW (85th percentile and above) per Centers for Disease Control guidelines. After collecting preliminary data, a power analysis was performed using average SMS scores between NW and OOW patients with an alpha of 0.5, determining a needed sample size of approximately 300 male and 300 female subjects.

Results: Five hundred ninety patients (296 female, 294 male) were identified. The SMS stage at presentation was significantly greater in OOW compared to NW patients for both females (5.9±1.8 vs. 5.2±1.7; P =0.003) and males (4.9±1.9 vs. 4.1±1.8; P =0.002). The major curve magnitude for OOW females was significantly different from NW females (36±16 degrees vs. 30±16 degrees; P =0.004). The major curve magnitude was not different for OOW and NW males ( P =0.3).

Conclusion: At initial presentation, OOW patients present at a greater skeletal maturity as measured by the SMS compared with NW patients. OOW female patients present with a greater major curve magnitudes than NW female patients. These results highlight negative implications of the pediatric obesity epidemic as it relates to the AIS population. These findings can be used to counsel families and provide anticipatory guidance for the AIS treatment plan.

Level Of Evidence: Level III-cross-sectional study.