A modified orbital index for CT-based risk stratification in pediatric and adolescent orbital floor fractures

Pediatric orbital floor fractures differ biomechanically from adult injuries owing to greater bone elasticity and incomplete sinus pneumatization. Surgical indications remain debated, as subtle radiologic findings may underestimate clinically significant muscle entrapment. The orbital index (OI), a quantitative CT-based metric developed in adult populations, has not been systematically evaluated in pediatric and adolescent patients. We evaluated the applicability of OI in pediatric orbital floor fractures and proposed a modified OI (mOI) incorporating fracture type to improve risk stratification. A retrospective review of 73 patients (<18 years) treated for orbital floor fractures between 2015 and 2024 was performed. OI and mOI values were derived from CT scans, and predictive performance for surgical indication was analyzed using receiver operating characteristic curves and logistic regression, with p<0.05 considered statistically significant. The mean age was 14.1±3.9 years. Among the 73 patients included, 62 (84.9%) were male and 11 (15.1%) were female. Surgical intervention was required in 51 (69.9%) patients. For OI≥4, sensitivity was 35.3% and specificity 100% (AUC=0.693, 95% CI 0.566-0.809, p<0.001). Incorporating fracture type (trapdoor=0, open-door=1) increased sensitivity to 49.0% (AUC=0.690, 95% CI 0.563-0.807, p<0.001) while preserving full specificity; paired sensitivity comparison showed improvement versus OI (p=0.041, McNemar test). mOI≥4 independently predicted surgical need (OR 5.2, 95% CI 2.1-12.8, p<0.001) and correlated with diplopia (p=0.028). The mOI improves the limited sensitivity of classical OI while maintaining high specificity and may serve as an adjunct CT-based risk-stratification tool to support non-emergent surgical decision-making in pediatric and adolescent orbital floor fractures.