Scaphocapitate fractures. Patterns of dislocation, mechanisms of injury, and preliminary results of treatment

The essential features of scaphocapitate fractures are transverse fractures of the scaphoid and capitate, with rotation of 180 degrees of the proximal fragment of the capitate. This complex injury is the result of severe trauma and is often missed on initial roentgenographic examination of the wrist. The authors reviewed the fourteen cases that were previously described and report seven additional cases. Six different patterns of fracture-dislocation, all possessing the essential features of this injury, are identified. The dislocation may involve the entire carpus or the isolated proximal pole of the capitate, or both. The importance of defining the relationship of the carpus and the proximal pole of the capitate to the lunate and distal articular surface of the radius on the lateral roentgenogram is emphasized. There is no single mechanism of injury that accounts for each of the lesions. The previously suggested mechanism - a blow to the palm with the wrist in severe dorsiflexion - accounts for a majority of the injuries. In at least three patients, however, a blow to the dorsum of the volar-flexed wrist appears to have been the cause. The choice of treatment is influenced by two factors: accurate diagnosis of the injury at the time of initial management, and the nature of the dislocation. The preliminary results of treatment in those patients followed for more than one year are that closed reduction was not successful as a rule. Therefore, open reduction with internal fixation is the preferred treatment.