Comparative evaluation of Risser sign and Kreitner–Kellinghaus modified system for age estimation using iliac crest ossification in Egyptians

Abstract Establishing whether an individual has reached the 18-year legal majority threshold is a central medicolegal task in Egyptian forensic practice. Iliac crest apophyseal ossification is a potentially valuable skeletal marker for this purpose during late adolescence, yet no population-specific normative data exist for Egyptians. This study retrospectively evaluated digital pelvic radiographs of 288 Egyptians (127 males, 161 females; aged 10–30 years) using three concurrent staging systems: Risser-US, Risser-Fr, and the Kreitner–Kellinghaus modified system (KK–MS). Age increased consistently with advancing stage in all systems. No statistically significant sex differences in ossification timing, although statistical power to detect such differences was limited at several mid-stages by small sex-specific subsamples. Complete apophyseal fusion was first observed at 15.5 years in males and 15.1 years in females under Risser-US, and at 15.8 years in males and 15.9 years in females under both Risser-Fr and KK–MS. ROC curve analysis for the 18-year threshold revealed that Risser-Fr (AUC = 0.953; specificity 95.7%) and KK–MS (AUC = 0.956; specificity 95.2%) achieved excellent discriminatory performance, whereas the Risser-US system (AUC = 0.806; specificity 61.2%) performed substantially worse due to its early complete-fusion age. These findings suggest that iliac crest apophyseal ossification may be a useful late‑maturing indicator for forensic age diagnostics in Egyptians and support the consideration of Risser-Fr and KK–MS staging as adjunctive tools in forensic age estimation protocols when pelvic radiographs are available. However, because complete apophyseal fusion under Risser-Fr and KK–MS was first observed as early as 15.8–15.9 years, attainment of these terminal stages cannot by itself exclude minority. Therefore, it should be regarded as raising the probability of adulthood rather than establishing it.