Distal radioulnar joint (DRUJ) injuries can occur separately or in conjunction with distal radius fractures and both-bone forearm fractures. In fact, nearly 60 percent of forearm fractures adversely affect the DRUJ.
The ulna is the stationary, stable anatomical point of reference for rotation of the forearm – around which the radius rotates in pronation and supination. The distal and proximal radioulnar joints form the forearm joint. Mobility and stability of the distal radioulnar joint is accomplished with fully congruent articulating surfaces and radioulnar ligaments that are strong and secured.
Following a distal radius fracture, the congruency is lost and stabilizing ligaments tear. DRUJ injuries are classified as stable, partially unstable (subluxation), and unstable (dislocation) patterns – depending on the injured structures and clinical findings.
The nature of the accident and area of pain is the first indication of possible DRUJ damage. A radiograph and possible CT scan can further identify the extent of the damage and area of instability. Accurate assessment of the stability of the DRUJ is challenging – particularly when late instability is suspected after the associated fractures have healed. A series of scans with the forearm in pronation, neutral and supination are recommended in order to compare the injured and uninjured joints.
Exploratory arthroscopy can also help identify stable and partially unstable lesions.
Once any associated fractures are addressed with internal fixation the remaining instability of the DRUJ is assessed. Treatment depends on whether an injury is a simple or complex dislocation. Reduction is the first course of action for a simple dislocation – accomplished with either direct pressure over the ulna with a period of mobilization or a period of directed mobilization, depending on the location.
In complex dislocations it may be necessary to reattach massive tears with the use of anchor sutures or pull-out wires. Depending on the level of instability, additional fixation of the joint may also be required – generally using Kirschner wires.