CT-imaging of variants of the medial clavicular epiphysis in a central European population: prevalence and impact on forensic age estimation.

INTRODUCTION: Computed tomography (CT) of the medial clavicular epiphysis is widely used for forensic age estimation in adolescents and young adults. However, morphological variants may complicate or prevent reliable staging, and their prevalence and impact remain insufficiently characterized. This study aimed to evaluate the frequency, distribution, and forensic relevance of variants of the medial clavicular epiphysis. METHODS: In this retrospective study, CT scans of 467 individuals aged 10-25 years were analysed. Variants were defined as fish-mouth, bowl-like, and multiple epiphyseal ossification centres (EOC). Each clavicle was assessed regarding type of variant, laterality, and feasibility of standard ossification staging. RESULTS: Variants were identified in 155/455 (34.1%) left clavicles and 161/455 (35.4%) right clavicles. They were significantly more frequent in male than in female individuals (53.0% vs. 20.9%, p < 0.001) and peaked during mid-adolescence. Fish-mouth and multiple EOC configurations were the most common variants. Staging was impossible in all bowl-like cases and in most multiple EOC and combined variants, whereas fish-mouth configurations frequently remained assessable. CONCLUSION: Variants of the medial clavicular epiphysis are common and significantly affect the applicability of forensic age estimation. While fish-mouth configurations may still permit staging, bowl-like and multiple EOC variants frequently preclude reliable assessment. IMPLICATIONS FOR PRACTICE: Given the high prevalence and significant impact of variants, careful assessment of epiphyseal morphology is essential prior to applying standard staging systems. In cases where variants are present, especially multiple EOC or bowl-like configurations, the limitations of clavicular age estimation should be clearly communicated. The identification of fish-mouth configurations as a potentially stageable variant may help refine diagnostic decision-making in borderline cases.