Review Question - QID 840

The radiograph demonstrates a flexion type supracondylar humerus (SCH) fracture. The ulnar nerve is most commonly injured with this type of fracture, and is manifested with intrinsic hand weakness.

In flexion type supracondylar humerus fractures, the distal fragment is displaced anteriorly. Specifically, the sharp spine of the proximal fragment most commonly injures the ulnar nerve. Extension type SCH fractures are more common than flexion type and are commonly associated with injury to the anterior interosseous nerve (AIN). Weakness of the flexor digitorum profundus to the index finger and flexor pollicis longus would be associated with AIN palsy. Wrist drop would be associated with radial nerve palsy. Weakness of extensor pollicis longus correlates with posterior interosseous nerve palsy. Ulnar nerve palsy would cause hand intrinsic weakness and clawing.

In the meta-analysis by Babal et al, they found that ulnar neuropathy occurred most frequently in flexion-type injuries, representing 91.3% of associated neuropraxias. Conversely, anterior interosseous nerve injury predominated in extension-type fractures, representing 34.1% of associated neuropraxias.

Incorrect Answers
Answer 1 is incorrect as weakness of the flexor digitorum profundus to the index finger would be associated with AIN palsy.
Answer 2 is incorrect as weakness of the extensor pollicis longus correlates with posterior interreous nerve palsy.
Answer 3 is incorrect as wrist drop would be associated with a radial nerve palsy.
Answer 4 is incorrect as weakness of the flexor pollicis longus is associated with an AIN palsy.