[Coronal fracture dislocation of the hamate and the base of the fourth metacarpal bone: a rare form of carpometacarpal injury].

Fractures of the hamate body and the base of the fourth metacarpal bone in the coronal plane with or without a dislocation of the base of the fifth metacarpal bone are rare. Clenched fist punches are considered to be the main cause. The diagnosis of the fracture dislocation is often missed on routine radiographs. Posterior-anterior, lateral, and oblique views are required for native radiological evaluation. A CT scan can help in the assessment of severity and for preoperative planning. Unless minimal displacement is present, non-surgical treatment does not lead to satisfying outcome. Displaced fractures of the hamate body and the base of the fourth metacarpal bone with or without subluxation of the hamatometacarpal joint should be stabilised by open reduction and internal fixation (ORIF). Controversy exists about the surgical treatment of choice. Screw or K-wire fixation with postoperative cast immobilisation for 6 weeks and consecutive hardware removal has been found to result in excellent clinical and radiological outcomes. This study presents 2 cases of coronal fractures of the body of the hamate and the base of the fourth metacarpal bone with subluxation of the hamatometacarpal V joint. Anatomy, epidemiology, classification, mechanism, clinical symptoms, diagnostic features, and therapy options for these injuries are discussed. © Georg Thieme Verlag KG Stuttgart · New York.