Ulnar Head Fracture with Volar Dislocation of the Distal Radioulnar Joint: A Case Series and Systematic Review.

Dislocations of the distal radioulnar joint associated with a fracture of the distal ulna articular surface without an associated radial fracture are extremely rare. We present a case of a fracture of the distal ulna with an associated dislocation of the distal radioulnar joint, where the articular head fragment was displaced anterior to the sigmoid notch. We also present the results of a formal systematic review of these injuries which confirmed this is the first such injury described, although there is a very similar fracture pattern described in the literature with dorsal dislocation. We describe the mechanism of injury and hypothesize about the etiology of the fracture pattern and suggest that it represents the end of a spectrum that also includes the isolated dislocations and those associated with an ulna styloid fracture.