Presentation
About 6 weeks before the presentation, the patient had undergone intramedullary nail fixation across the left radius and ulna shaft fractures. He presented with the clinical signs of the ulnar neuropathy which were absent at the time of injury. He was referred for the ultrasound evaluation of the ulnar nerve.
Patient Data
There is a volar displacement of an ulnar bone fragment causing acoustic shadowing. The bone fragment penetrates the posterior surface of the ulnar nerve. The ulnar nerve is elevated from its course. In the axial images, most of the nerve fibers show loss of normal fascicular pattern with edema. However, few fibers of the nerve show a normal echo pattern.
The ulnar artery is also displaced by the bone fragment. The artery is patent with normal color flow and waveform.
In absence of the bridging ossified callus from ulnar shaft fracture, a short length of an intramedullary nail is seen causing a reverberation artifact.
There is no local collection.
1st photo shows the volar displaced ulnar bone fragment. The ulnar nerve is retracted to the side.
After removal of the bone fragment, 2nd photo was taken showing a penetrating injury to the ulnar nerve.
3rd photo shows a mobilized ulnar nerve.
Case Discussion
An adult male had closed forearm injury resulting in radius and ulna shaft fractures. He was surgically treated with intramedullary nailing across the fractures. By the end of a few weeks after the surgery, the patient developed signs of the ulnar neuropathy. He was referred for the ultrasound to rule out/rule in the ulnar nerve injury and its location. Ultrasound shows a volar displaced ulnar bone fragment penetrating the ulnar nerve.
Surgical exploration was done. The bone fragment was removed and the nerve was mobilized.
The ulnar nerve injury is a rare complication of closed fractures of the forearm2,3.
Intraoperative photos courtesy: Operating surgeon Dr. Nisarg A. Patel.