Metopism in Humans: Global Prevalence, Morphological Variations, and Clinical Implications: A Systematic Review

Abstract

Background: The metopic suture is the median frontal suture that normally fuses during early childhood as the two halves of the frontal bone unite. Its persistence into adulthood, termed metopism, is a well-recognised but inconsistently understood anatomical variant with anthropological, radiological, forensic, and surgical relevance. Objective:. Methods: A structured literature search was conducted across PubMed, ResearchGate, Google Scholar, and allied anatomical and forensic-medicine journals, following a PRISMA-informed selection process. Studies reporting prevalence data, morphological description, or clinical/forensic associations of the metopic suture in adult human crania or radiographic datasets were included. Results: Reported prevalence of complete metopism ranges from below 1% to over 9% across populations, with markedly higher rates of partial or incomplete metopic remnants (up to 38–44%) in some samples. European and East Asian ancestries generally show the highest rates of complete metopism, whereas sub-Saharan African and several South-East Asian samples show lower or highly variable rates. Morphologically, metopism presents as complete, incomplete, or ridge-like variants, occasionally co-occurring with Wormian bones or frontal sinus anomalies. Clinically, metopism is important chiefly because it can mimic a frontal bone fracture on imaging, may alter craniometric measurements used in forensic sex and ancestry estimation, and must be distinguished from pathological metopic craniosynostosis. Conclusion: Metopism is a benign, population-variable anatomical trait whose recognition is essential across radiology, neurosurgery, forensic anthropology, and craniofacial medicine. Standardised reporting criteria and multi-centre radiological studies are needed to clarify its true global distribution and clinical significance.