11-06: Forearm Fractures

Clinical Summary

Fractures of the wrist and elbow usually involve a fall onto the outstretched arm, while isolated fractures of the ulnar shaft are more commonly from a direct blow. AP and lateral views of the wrist, forearm, and elbow are required when a forearm fracture is suspected. Functional hand deficits can identify the possibility of an occult injury to forearm neurovascular structures, which could require immediate surgical intervention.

Monteggia fracture-dislocation is a fracture of the ulna (usually proximal third) with an associated proximal radial head dislocation; it is occasionally associated with radial nerve injury. Galeazzi fracture-dislocation is a fracture of the distal one-third of the radius with dislocation of the distal radioulnar joint. It occurs three times more often than a Monteggia fracture and can be associated with ulnar nerve injury. Isolated fractures of the ulna’s middle third may result from direct trauma, while the forearm is used to block the blow (nightstick fractures).

Management and Disposition

Both Monteggia and Galeazzi fracture-dislocations require emergent orthopedic consultation and are treated with immobilization in a long-arm splint (with elbow flexed at 90 degrees). The forearm is placed in a neutral position for a Monteggia fracture and supinated for a Galeazzi fracture. Treatment is usually surgical for both injuries, although children may be treated by reduction and casting.

Pearls

1. Any ulnar fracture with greater than 10 degrees of angulation or with a bony fragment displaced more than 50% usually requires surgical correction.

2. Do not be satisfied with the diagnosis of an isolated proximal third ulnar shaft fracture. A line drawn through the radial shaft and head must align with the capitellum in all views to exclude dislocation.

3. An ulnar styloid base fracture can be a clue to a Galeazzi fracture.

4. Since the radius and the ulna create a ring, injury to one of the bones of the forearm is often associated with fracture or dislocation of the other. Consequently, upon recognition, one must continue to seek out the other half of the injury by examining both the elbow and wrist joints.

5. Fractures of the forearm may result in compartment syndrome.

6. GRUM is a mnemonic used to remember what fragment is fractured in the Galeazzi and Monteggia fracture patterns: Galeazzi Radius, Ulna Monteggia.