What is your diagnosis?

Monteggia injury of the right upper extremity. There is a radial head dislocation with probable plastic deformation of the ulna. 

• Pearl: When examining for acute nerve injury, extra focus should be on the posterior interosseous nerve, which may be injured by the displaced proximal radius [1]. This can be evaluated by testing for finger extension at the MCP, wrist pronation and wrist supination.

What actions on radiographs can help diagnose this?

Assess the radiocapitellar line on radiographs of the elbow. A line down the center of the shaft and head of the radius should intersect the capitellum in all positions, in any projection [2].

Image 3. Case courtesy of Dr. Samir Benoudina. Radiopaedia.org, rID: 41196

If there is ever a concern or difficult case with a pediatric patient, always consider obtaining radiographs of the opposite, unaffected extremity, in order to assess further for clinical differences.

Images 4 and 5. Lateral x-rays of injured right and contralateral left elbow for comparison, taken in clinic 1 week after injury was missed on initial presentation. Images by author.

What parts of the history can help differentiate pediatric elbow pain?

The mechanism of injury can help key in on differentiating between a fracture/dislocation pattern or radial head subluxation, otherwise known as nursemaid’s elbow. A fall, as in this patient, is more likely to be associated with fracture/dislocation, whereas longitudinal traction would more likely be a nursemaid’s elbow. The classic example for a nursemaid’s elbow, is a parent pulling on the child’s arm. This can help guide management when the diagnosis may be uncertain.

What is the classification name and what are the types within it?

The Bado Classification differentiates types of Monteggia fractures

What is your disposition and management? Does orthopedics need to be consulted?

Urgent reduction and placement in a long arm splint with orthopedic consultation. Orthopedics should be consulted in the management of any Monteggia fracture due need for operative repair.

• Pearl: Reduction is achieved by:

Anteriorly dislocated radial head

• Having forearm in full supination with longitudinal traction

• Flex elbow gently to >90 deg to relax biceps 

• The radial head is gently repositioned by direct manual pressure anteriorly on the bone. Leave radial head in flexion

• The ulnar shaft is reduced by firm manual pressure (if needed)

Posteriorly dislocated radial head

• Apply traction to forearm with the forearm in full extension