These are fractures that involve the diaphysis of the radius or of the ulna or both simultaneously. They represent the 3.15% of the total of the surgically treated fractures that have been reviewed.

The significance of the fractures of this segment lies in the interdependence between the reduction of one bone and the function of the other bone, as well as their influence upon the function of the wrist, that is to say, of the hand. The important movement of pronation and supination depends on the anatomic reduction of a grossly straight bone around which a curved bone turns, a curve that must be reconstructed.

The anatomy of the radius can not be reconstructed with intramedullary implants; thin nails will not give enough stability while thicker nails will straighten the curvature. The fractured ulna is prone to develop a pseudoarthrosis when the stability is not optimal; This is why its internal fixation with a plate is mandatory. However, in cases of open fractures of both bones with skin loss, the provisional intramedullary nailing of the ulna may be a valid alternative, whether associated to an external fixator or not.

The suitable implants are the small fragment plates, that must be properly contoured. The cross-section of the plate, straight or tubular, and its length will depend on the size of the bone. The semi-tubular plates with 4.5 mm screws should only exceptionally be used.

In spite of the small size of the diaphysis of the bones of the forearm (relative to the other long bones), it still is important to substitute any bone loss with autologous cancellous bone graft. The existence of the interosseous membrane must be kept in mind at the time of bone grafting because its induced ossification will cause disability.