Routine radiography

Computed tomography (CT)

Magnetic resonance imaging (MRI) (Table 8-1)

Eighty percent of distal humeral fractures occur in children.

Fifteen percent of physeal fractures in children involve the distal humerus.

The mechanism of injury is a fall on the outstretched hand.

Fractures may be flexion or extension injuries. Extension injuries are 10 times more common than flexion injuries.

Fractures usually are obvious on AP and lateral radiographs. CT with coronal and sagittal reformatting if helpful for evaluating subtle injuries. MRI is useful for physeal fractures in young children.

Treatment: closed reduction

Complications: neurovascular injury, premature physeal closure, arthrosis, malunion, nonunion

Avulsion fractures of the epicondyle are common in children.

The injury is common in throwing athletes, specifically pitchers.

The medial epicondyle is particularly vulnerable between ages 9 and 14 years.

Mechanism of injury is varus and valgus forces. Medial epicondylar fractures are common; lateral epicondylar fractures are rare.

Displaced medial epicondylar fragments may be trapped in the joint.

Routine radiographs usually are adequate for diagnosis. MRI is useful for subtle undisplaced fractures and associated soft tissue injuries.

Treatment: closed reduction for undisplaced fractures; pinning of displaced (>3 mm) fractures.

Complications: fragment entrapped in joint, instability.

The distal humerus consists of medial and lateral columns with the trochlea between the two columns.

The mechanism of injury is trochlear impaction into the humeral articular surface with flexor and extensor muscles causing displacement of the epicondyles.

Fractures may be nonarticular, involve one condyle or have a “T” or “Y” configuration with varying degrees of comminution.

Treatment: internal fixation commonly required

Routine radiographs usually are diagnostic. CT with coronal and sagittal reformatting is important for operative planning.

Complications: poor reduction, exuberant callus, reduced range of motion, arthrosis, nonunion (2%–10%), nerve compression (15%), and postoperative infection.

Capitellar fractures account for 1% of elbow injuries.

Fractures may involve the entire capitellum or the articular surface, or be comminuted and involve the radial head.

Mechanism of injury: direct blow or fall on the outstretched hand with force transmitted from the radius to the capitellum.

Subtle fractures may present with a positive fat pad sign and may require CT or MRI for detection.

Treatment: Loose fragments may require removal. K-wire fixation of large fragments may be necessary in certain cases.

Fractures of the radial head and neck are common, accounting for one third of elbow fractures. Fractures are categorized as three types based on displacement or comminution of the radial head or neck. Type I, undisplaced (<2 mm) head or neck fracture; Type II, displaced head or neck fracture; Type III, comminuted head or neck fracture.

Mechanism of injury: Fall on the outstretched hand with the elbow partially flexed and pronated.

Associated elbow, forearm, and wrist injuries may be present.

Routine radiographs may be normal, except for a positive fat pad sign. Follow-up in 10 to 14 days may demonstrate the fracture. MRI or CT may be required for detection of subtle fractures and for operative planning with complex fractures.

Treatment: Undisplaced fractures are treated with closed reduction. Displaced or comminuted fractures may require internal fixation, resection, or arthroplasty.

Complications include associated ulnar fracture, heterotopic ossification, instability, and arthrosis.

The ulnar is susceptible to trauma because of its superficial location.

Mechanism of injury: direct blow after fall on the flexed elbow.

Most fractures are intra-articular.

Triceps fascia disruption leads to significant displacement and articular deformity.

Routine radiographs usually are diagnostic. The lateral view is most useful.

Treatment: Joint congruity must be restored, which usually requires internal fixation for displaced fractures.

Complications: instability, decreased range of motion (3%–50%), articular deformity and arthrosis, ulnar neuropathy (10%), and nonunion (5%).

Isolated coronoid fractures are uncommon. There are three categories of fracture. Type I: small avulsion of the coronoid tip. Type II: fracture involves 50% of the coronoid, but does not extend to the base. Type III: fracture of the coronoid base.

Coronoid fractures are seen most commonly with posterior dislocations.

Recurrent dislocation is common after coronoid fracture/dislocation.

Displaced fractures can be detected on radiographs. The lateral view is most useful. CT may be required for detection of undisplaced fractures.

Treatment: Closed reduction is adequate in most cases.

Complications: instability, arthrosis, recurrent dislocation.

Dislocation classifications refer to the position of the dislocation.

Most elbow dislocations are posterior and involve both the radius and ulna.

The mechanism of injury is a fall with the elbow extended.

Anterior, medial, and lateral dislocations are uncommon.

Associated injuries include coronoid, radial head, epicondylar fractures, and neurovascular injuries.

Postreduction CT imaging is important to fully assess the joint space and associated fractures.

Complications include arthrosis, instability, decreased range of motion, neurovascular injury, and extensive heterotopic ossification.

Monteggia fracture or lesion is a dislocation of the radial head with an associated proximal ulnar fracture.

This injury accounts for only 7% of ulnar fractures and 0.7% of elbow injuries.

Four injury patterns are commonly described:

Mechanism of injury: direct blow to posterior ulna, fall on the outstretched hand with elbow flexed, or hyperextension.