Simultaneous palmar divergent dislocation of scaphoid and lunate concurrent with i psilateral humeroradial joint dislocation and humerus shaft fracture: report a rare case and add a new subtype

Background: Simultaneous palmar dislocation of scaphoid and lunate is a rare condition generally resulting from high-energy trauma and usually classified into two types. The literature has only reported nine patients with palmar divergent dislocation of scaphoid and lunate. Here we we present a case of accompanied ipsilateral humeroradial joint dislocation and open humeral shaft fracture caused by the same violence travelling from the wrist. Considering the emerging cases with their own characteristics, we suggest this severer injury be expanded into the third type of palmar dislocation of scaphoid and lunate. Case presentation: A 31-year-old male who fell from a three-storey building, with his right wrist directly hitting the ground, was admitted to the orthopaedic department of our hospital. Physical and radiographic examinations defined simultaneous palmar divergent dislocations of scaphoid and lunate concurrent with ipsilateral humeroradial joint dislocation and open humeral shaft fracture. After debridement and internal fixation for humerus and close reduction for humeroradial joint, the scaphoid and lunate were treated with open reduction and fixation by Kirschner’s wires, and the palmar scapholunate ligament and anterior capsule were repaired through volar approach. After a 3-year follow-up, his humeral fracture healed without recurrent dislocations, collapse or avascular necrosis of scapholunate. Favorable hand function regained . Conclusions: Palmar divergent dislocation of scaphoid and lunate caused by considerable violence is rare and appropriate to urgent open reduction and fixation with Kirschner’s wires and repair of the stronger palmar scapholunate ligament through single volar approach. When the residual violence continues to transmit to the upper extremity, ipsilateral dislocation or fracture may occur. We advise that this complex injury be classified into a third subtype of simultaneous palmar dislocation of scaphoid and lunate to avoid misdiagnosis.