title: Hamate and pisiform coalition: a case report and introduction to the carpal C-sign on lateral radiograph.
abstract: Hamate-pisiform coalition is an exceptional form of carpal coalition. Case reports are essential to gain a better understanding of this variant. We report a case of congenital bilateral hamate-pisiform coalition in a 20-year-old male discovered in the context of a right wrist trauma. Radiographs also revealed a bilateral scapholunate diastasis. Clinical examination and radiological findings suggested that the right wrist scapholunate diastasis was related to scapholunate instability. Left wrist scapholunate diastasis could be related to (1) a pathological feature or (2) a normal variant associated with hamate-pisiform coalition. Lateral radiographs showed a volar C-shaped osseous bridge corresponding to the coalition. We associated it with a new sign: the "carpal C-sign". Computed tomography with three-dimensional reconstruction provides helpful information about the type of coalition (osseous versus non-osseous) and excludes potential fracture. We discuss the specific embryologic features of the hamate-pisiform coalition, as well as its prevalence, radiographic classification, clinical significance, and treatment.
authors.affiliation: Radiology Department, Hôpital Bicêtre, 78 rue du Général Leclerc, 94266, Le Kremlin-Bicetre, France. jon.cortese@live.fr.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Cortese
authors.affiliation: Orthopaedic Department, Hôpital Bicêtre, 78 rue du Général Leclerc, 94266, Le Kremlin-Bicetre, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Soubeyrand
authors.affiliation: Radiology Department, Hôpital Bicêtre, 78 rue du Général Leclerc, 94266, Le Kremlin-Bicetre, France.
authors.forename: Leo
authors.initials: L
authors.lastname: Razakamanantsoa
authors.affiliation: Radiology Department, Hôpital Bicêtre, 78 rue du Général Leclerc, 94266, Le Kremlin-Bicetre, France.
authors.forename: Marie-France
authors.initials: MF
authors.lastname: Bellin
authors.affiliation: Radiology Department, Hôpital Bicêtre, 78 rue du Général Leclerc, 94266, Le Kremlin-Bicetre, France.
authors.forename: Maud
authors.initials: M
authors.lastname: Creze
mesh_terms: D000328:Adult; D002348:Carpal Bones; D003287:Contrast Media; D003937:Diagnosis, Differential; D051225:Hamate Bone / Q000000981:diagnostic imaging*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008023:Ligaments, Articular / Q000000981:diagnostic imaging / Q000293:injuries* / Q000601:surgery*; D008297:Male; D061330:Multidetector Computed Tomography / Q000379:methods; D051220:Pisiform Bone / Q000000981:diagnostic imaging*; D011856:Radiographic Image Enhancement / Q000379:methods; D011859:Radiography / Q000379:methods; D014954:Wrist Injuries / Q000000981:diagnostic imaging*; D014955:Wrist Joint / Q000000981:diagnostic imaging; D055815:Young Adult
chemical_list: D003287:Contrast Media
keywords: Carpal C-sign; Coalition; Congenital variation; Hamate; Pisiform; Scapholunate instability