Elbow Injury

July 12, 2017
Brady Pregerson, MD
Brady Pregerson, MD

What type of injury is seen on this x-ray of a young boy's elbow? Outward signs of trauma are negligible.

A 4-year-old male is brought by his mother to the emergency department for 2 days of left elbow pain following a fall. The elbow initially did not appear badly injured so the boy’s parents elected to wait until the following day before obtaining care. Today the arm looked somewhat swollen and the child was still complaining of pain and was not using the arm.

Vital signs were normal. Physical examination was normal except for guarding and tenderness of the left elbow as well as decreased ability to fully supinate or extend the elbow. No deformity is observed beyond mild swelling. X-ray image is shown below.

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What does the x-ray image show?

What should you do next?Answer and disucssion>>

Answer: The image shows a positive fat pad sign signifying an occult intra-articular elbow fracture. The fat pad sign is the semi-lucent area just anterior and posterior to the distal humerus. In a child, this is likely from a supracondylar humeral fracture (in an adult a radial head fracture is more likely).

 

Discussion

The most common pediatric elbow injuries requiring treatment are a “nursemaid’s” elbow, which is a radial head subluxation, and a supracondylar fracture of the humerus. With a nursemaid’s elbow, the mechanism of injury is typically one of traction and exam will show limited range of motion but no significant swelling.  X-rays are not necessary, but if done results will be normal. With a supracondylar fracture of the humerus the mechanism is typically a fall and exam will show swelling in addition to decreased range of motion; x-rays may show a fracture, or in the case of an occult fracture, nothing more than a positive fat pad sign. Normally the elbow joint has both an anterior and a posterior fat pad, and these are both tucked in close to the bone. With a fracture, blood leaks into the joint capsule and displaces these fat pads. Even when the fracture cannot be visualized, the displacement of the fat pads is apparent.

Treatment of a nursemaid’s elbow involves relocation followed by assessment for return to normal function.  No other treatment is necessary. 

Treatment of a supracondylar fracture of the humerus varies depending on severity and involves anything from discharge home with a long arm splint and sling, to admission for observation and prevention of compartment syndrome, with open reduction and internal fixation eventually required.   

Case Conclusion: This child had a non-displaced fracture and was sent home with instructions for orthopedic follow-up.

Please scroll down for Excerpt on PEDIATRIC ELBOW INJURIES from The Emergency Medicine 1-Minute Consult Pocketbook

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