Session VIII - Upper Extremity

The Importance of the Distal Radio-Ulnar Joint in Distal Radial Fractures

Daniël V.C. Stoffelen, MD, PhD; Paul L.O. Broos, MD, PhD, University Hospital Gasthuisberg, Leuven, Belgium

Purpose: The purpose of the study was to determine the importance of the distal radioulnar joint in the final outcome of distal radius fractures.

Methods: In a prospective study we evaluated the results of 272 distal radial fractures by their involvement of the distal radioulnar joint. A prospective protocol was used to follow the patients for one year. A Cooney score was used to evaluate the functional outcome. Residual deformities, grip strength, wrist movements and finger stiffness were evaluated. Specific tests for the distal radioulnar joint were performed (a stability test, forearm rotation test, forearm rotation compression test and forearm rotation strength). The presence of an ulnar styloid avulsion, either at the tip or at the base was also investigated.

Children and patients with bilateral fractures, neurological or psychological disorders and multiple injuries were excluded from this study. Before starting the clinical set-up, an experiment was conducted to evaluate the exact fragment displacement of the distal radius fracture.

Results: From the experiment we concluded that the distal fragment of the radius displaces in a three-dimensional plane. Both shortening, dorsal angulation and rotation around the distal radioulnar joint are present in the fracture pattern.

From the clinical test, a significantly worse outcome was found with a dorsal angulation of 10° and a radial shortening of more than 4 mm. The radioulnar function is impaired with the same amount of abnormality seen radiographically. Also ulnar styloid avulsions have a significantly worse effect on the final outcome especially in "simple" wrist fractures.

Discussion and Conclusion: The distal radioulnar joint plays an important (and probably the most important) role in the final outcome of distal radius fractures. Apart from "general" causes of dysfunctions such as nerve lesions or Südeck dystrophy, the distal radioulnar joint is the major component in restoring wrist function. Both for extra- and intra-articular fractures of the distal radius, malunion will result in dysfunction of the distal radioulnar joint.

Although forearm rotation occurs at the elbowlevel and at the distal radioulnar joint, it is a motion occurring through both bones of the forearm. As even in the so-called extra-articular fractures of the distal radius, the supination can be diminished by either shortening or dorsal angulation. This means that every fracture at the distal radius is in a certain sense intra-articular and that in all fractures of the distal radius one should try to achieve as good an anatomical reduction as possible.