# Isolated Volar Radioulnar Joint Dislocation With Associated Ulnar Styloid Fracture

## TL;DR

A rare wrist injury involving dislocation and fracture is described, highlighting diagnostic challenges and treatment approaches.

## Contribution

The paper presents a case emphasizing the importance of CT scans and ultrasound-guided nerve blocks for accurate diagnosis and pain management.

## Key findings

- Initial radiographs failed to detect the injury, but CT scans revealed a volar dislocation and ulnar styloid fracture.
- Ultrasound-guided ulnar nerve block provided effective analgesia for treatment.
- The case underscores the need for advanced imaging when physical exams are inconclusive.

## Abstract

Isolated volar dislocation of the distal radioulnar joint is a rare occurrence and is commonly missed. The mechanism of injury typically involves hypersupination. True lateral radiographs are difficult to obtain as patients are usually limited with wrist pronation and supination, resulting in a high miss rate. We describe a 32-year-old male who presented to the emergency department (ED) with pain and swelling of the posteromedial aspect of the right wrist after punching a wall one hour prior to presentation. Examination revealed soft tissue tenderness and mild edema at the right distal ulna with an associated deformity, best visualized at the volar aspect of the right wrist. Active range of motion was limited with right wrist flexion and extension, secondary to pain and edema. Right wrist supination and pronation strength and range of motion were limited due to the patient’s tenderness on examination. Peripheral nerve function and vascular examination were normal. Initial radiographs of the right hand, wrist, and forearm did not reveal a fracture or dislocation. A musculoskeletal computed tomography (CT) scan of the right hand and wrist revealed an avulsion fracture of the ulnar styloid with volar displacement of the ulna. Analgesia was achieved with an ultrasound-guided ulnar nerve block, and the right wrist was successfully reduced. This report highlights the difficulty in obtaining a diagnosis of an isolated volar dislocation of the distal radioulnar joint. We recommend obtaining a musculoskeletal CT scan in the setting of an inconclusive radiograph and incongruent physical examination. Analgesia can also be achieved with an ulnar nerve block under ultrasound guidance.