CASE 1

An 8-year-old girl is brought to the ER by her mother after she fell from the monkey bars during recess at school. She had immediate pain, deformity, and swelling of the elbow after the fall. Upon arrival to the ER, the following radiographs were obtained (Figs. 10–1 and 10–2).

Figure 10–1

Figure 10–2

On examination, the patient is cooperative, but not able to move her fingers in‌

all the ways that you ask her to do. The most likely nerve injury with this fracture is:

1. Radial nerve

2. Axillary nerve

3. Median nerve

4. Ulnar nerve

5. Anterior interosseus nerve

Discussion

The correct answer is (A). With supracondylar humerus fractures, the humeral shaft is what causes the nerve injury. The direction that the humeral shaft displaces tells you which nerve is injured. For this patient, the distal fragment is posterior and medial, which means the shaft is anterior and lateral. The nerve most likely injured by a shaft that goes anterior and lateral is the radial nerve. If the shaft had gone anteromedially and the distal fragment posterolateral, the anterior interosseus branch of the median nerve would have been the correct answer. A preoperative ulnar nerve neurapraxia occurs in the setting of a flexion-type supracondylar humerus fracture. The axillary nerve is not usually injured in a supracondylar humerus fracture.

The patient is taken to the operating room and a reduction is successfully obtained via closed means. Three lateral pins are placed to hold the reduction. Following surgery, the nerve is still not functioning. The most appropriate next step would be:

1. Immediately return to OR for nerve exploration.

2. Observe overnight and take back to OR the following day if the fingers are not moving normally.

3. Observe for a week.

4. Observe for 6 weeks and then obtain EMG/nerve conduction studies if nerve function has not recovered.

5. Observe for 3 to 6 months and then obtain EMG/nerve conduction studies if nerve has not recovered.

Discussion

The correct answer is (E). Most nerve injuries that occur with supracondylar humerus fractures are neuropraxias, and resolve without any further intervention. Three to six months is given to allow for spontaneous resolution before

considering further testing. If the nerve was out preoperatively, then persistent nerve dysfunction is expected in the first several days/weeks postoperatively. The other answers are incorrect because they do not allow for sufficient time for self-recovery of the nerve and expose the patient to potentially unnecessary surgical intervention.

This patient was treated with three lateral pins. Which nerve is at risk with this technique? Had a medial wire been used for a crossed-pin technique, which nerve would have been at risk?

1. Radial and ulnar

2. Median and ulnar

3. Ulnar with both

4. Median for both

5. Radial and median

Discussion

The correct answer is (B). Meta-analysis data has shown us that the lateral wires can put the median nerve at risk. Multiple studies have shown that medial wire placements put the ulnar nerve at increased risk.

Objectives: Did you learn...?

Neurapraxias about the elbow associated with different fracture displacement patterns in supracondylar humerus fractures?

The appropriate management of neurapraxias that occurs at the time of injury in fractures of the distal humerus?

The nerves at risk with pin fixation for supracondylar humerus fractures?