Bennett fracture combined with hamate fracture: carpometacarpal joint ‘diagonal’ fracture and dislocation: a case report

BACKGROUND: Multiple carpometacarpal fractures and dislocations are rare. This case report describes a novel multiple carpometacarpal injury, namely, ‘diagonal’ carpometacarpal joint fracture and dislocation. CASE PRESENTATION: A 39-year-old male general worker sustained a compression injury to his right hand in the dorsiflexion position. Radiography indicated a Bennett fracture, hamate fracture, and fracture at the base of the second metacarpal. Subsequent computed tomography and intraoperative examination confirmed an injury to the first to fourth carpometacarpal joint along a diagonal line. The normal anatomy of the patient’s hand was successfully restored via open reduction combined with Kirschner wire and steel plate fixation. CONCLUSION: Our findings highlight the importance of taking the injury mechanism into account to avoid a missed diagnosis and to choose the best treatment approach. This is the first case of ‘diagonal’ carpometacarpal joint fracture and dislocation to be reported in the literature.