The Change in Position between the Ulnar Head and Radiusin Distal Radiounlar Joint following Distal Radius Malunion : Analysis on the Axial Planeusing Computed Tomography / 대한정형외과학회잡지

ABSTRACT

PURPOSE: This study examined the displacement of the ulnar head with respect to the distal radius after distal radius malunion on the axial plane using computed tomography. MATERIALS AND METHODS: Twenty-four patients with a residual dorsal tilt > 10degrees or radial shortening > 2 mm than the normal side, and no limitation in wrist rotation after radius union were enrolled in this study. The bilateral CT scans were obtained in 70degrees pronation, neutral, 70degrees supination. The radioulnar ratio was measured and the ratios of the abnormal side were compared with those of the opposite normal side. The results were statistically analyzed using a two-tailed paired t-test. RESULTS: The ulnar head of the patients with a malunited radius had a tendency for anterior translation compared with the normal side. In patients with a dorsal tilt deformity, the anterior translation of the ulnar head with respect to the radius was significant, particularly in the supination and neutral position. However, no significant difference was found in patients with radial shortening in terms of the ulnar head translation between the normal and abnormal side. CONCLUSION: These results might explain the mechanism of distal radioulnar joint instability and low incidence of ulnocarpal impingement in patients with distal radius malunion.