An Evaluation of the Effects of Elevated Body Mass Index on Skeletal Age

Background: Many treatment decisions in children’s Orthopaedics are based on age. This study determined whether a discrepancy between chronological age (CA) and skeletal age (SA) is dependent on BMI and if overweight or obese children would have an advanced SA. Materials: and Methods 120 children between ages 8-17 with an adequate hand radiograph and a correlating BMI were enrolled by retrospective chart review. Stratification based on age, sex, ethnicity, and BMI percentile was performed. For each age group, 6 males and 6 females were selected with 50% of each group having an elevated BMI. Two blinded physicians independently evaluated hand radiographs and recorded the SA. Statistical analyses evaluated inter-rater reliability and any discrepancy between groups. Results: The final statistical analysis included 96 children. The Intraclass Correlation Coefficient for SA determined by the two reviewers was excellent at 0.95. A difference of 13 months was found between CA and SA in the elevated BMI cohort versus the non-elevated BMI cohort, (p<0.001). No significant difference was seen between CA and SA for the non-elevated cohort (p=0.72), while matching for age and sex. Conclusion: Chronological age and skeletal age are not always equivalent especially in pediatric patients who are overweight or obese.