Bipartite trapezium – rare congenital accessory bone: a case report of two bilateral cases among related patients and description of new accessory bone – os scaphocapitatum anterius

These cases represent the first familial report of a bipartite trapezium and introduce a previously unreported volar accessory carpal bone, for which we propose the term os scaphocapitatum anterius. Awareness of such variants is crucial for accurate radiological interpretation and appropriate surgical planning, particularly in cases of trauma or CMC joint pathology, when such variants might be confused with fracture. Advanced imaging modalities such as CT are recommended to confirm morphology and distinguish congenital variants from post-traumatic changes.