FRACTURE OF BOTH FOREARM BONES
Fractures of the shafts of the radius and ulna are usually significantly displaced and are often comminuted because of the great force needed to break these strong bones. Anatomic reduction of the fractures, with full restoration of both the length and the bow of the radius, is essential to maintain maximal function of the forearm. Even when anatomic reduction is achieved, some long-term loss of supination and pronation may occur.
ORIF of fractures of both forearm bones is performed through separate incisions, maximizing the skin bridge left between the two. Both fractures must be reduced and held with clamps before either is permanently fixed; this ensures that both fractures are reduced anatomically and that the reductions are maintained. After the temporary reductions are secured, the less comminuted fracture (usually the ulna) is fixed with a compression plate and screws; the more comminuted fracture is fixed subsequently using the same technique.
A number of difficulties may be encountered during the surgical procedure. Extensive comminution may make it difficult to restore the bones to their proper length. In this situation, the interosseous membrane is identified, proximally and distally, and used as a guide in restoring the bones to an adequate length. Recreation of the anatomic bow of the radius is critical, and loss of the normal geometry will lead to permanent loss of forearm rotation. In wound closure, the fascia is left open and only the skin is closed, because tight fascial closure combined with postoperative swelling may produce a compartment syndrome.
Long-term problems associated with fractures of both forearm bones include nonunion, infection, limited motion, and synostosis between the radius and the ulna. Synostosis is rare and is usually associated with comminuted fractures at the same level in the forearm that result from crushing forces. Operative fixation through one exposure is another well-documented cause of synostosis. Nonunion can occur from inadequate fixation (e.g., using plates of insufficient strength or of improper length). One must ensure that six cortices of fixation on each side of the fracture are achieved, and 1/3 tubular plates (although easy to contour) are never appropriate for operative fixation of forearm fractures. Nonunion also occurs with closed reduction and plaster cast immobilization, and in the adult population fractures of both forearm bones are an absolute indication for ORIF.