"This is the best I can do," said the x-ray tech as he pulled me into the room. He added, with some exasperation, "I can't position him because he won't move his wrist."
Defensively, the patient countered, "He doesn't understand. I can't move my wrist."
The images were not what I expected. I had expected to see an obvious fracture. This was a simple case, a FOOSH injury with limited wrist range of motion. The distal radius clinically appeared deformed, prominent, and swollen. He was supposed to have a Colles fracture. I tried to coax more images by promising more pain medicine. With a hint of annoyance in his voice, he reiterated, "Again, it isn't that I don't want to. I can't move my wrist!"
The series was completely inadequate. Maybe a CT. I realized I had no clue what position the patient had to be in to do a wrist CT. The CT tech explained that the patient was traditionally prone with the arms extended overhead and hands palm down. That was impossible. My man couldn't pronate at all. I pleaded for a shot at supine position.
It worked. A half hour later I received a call from the radiologist. The reading: laterally impacted intra-articular fracture of the distal ulna with the impaction against the distal radius and ulnar rotational subluxation. She added, "This is weird. I think you should call the orthopedist."
The 3D reconstruction clearly shows the ulna has slipped out of place palmarly. One should never be able to see both sides of the ulnar notch of the distal radius. The axial images revealed the subluxed, fractured ulna to be caught up on the anterior lip of the ulnar notch.
It was the DRUJ — the distal radioulnar joint! Forearm rotation is controlled by the DRUJ. In fact, when the ulnar head is subluxed volarly, pronation is significantly restricted. The prominent, odd appearance of the distal radius was actually because the companion ulna was not where it was supposed to be.
The patient had been telling me his diagnosis all along. My job was to advocate for him and to convince others that he truly had something wrong. Not long after the orthopedist saw the CT, the wayward ulna was popped back in place in the OR. My guy was discharged with a rotatable wrist later that day.
Take Home Point:
When wrist supination or pronation is limited specifically, consider distal radioulnar joint injury.
The red arrow points to the radial articular surface of the ulnar notch. The blue arrow shows the subluxed ulnar articular surface for the radioulnar joint, and the yellow arrow points to the impacted ulna at the anterior lip of the radial ulnar notch with several bony fracture fragments.