Effect of Radial Lengthening on the Stability of the Distal Radioulnar Joint: A Biomechanical Cadaveric Study.

Abstract

Radial lengthening has been clinically proposed as an alternative treatment for distal radioulnar joint (DRUJ) instability associated with distal radius fractures based on the hypothesis that it functions in a manner similar to ulnar shortening. This study evaluated DRUJ stability under varying degrees of radial lengthening and examined whether the distal oblique bundle (DOB) enhances its stabilizing effect. Eight fresh-frozen cadaver specimens were used. DRUJ translation distances were measured using a custom stress test machine simulating the DRUJ ballottement test. A triangular fibrocartilage complex injury model was created arthroscopically to induce DRUJ instability. Stress tests were then conducted after radial lengthening of 1 mm, 3 mm, and 5 mm, recording translation distances. Two-way analysis of variance with multiple comparison post hoc tests was used to determine differences under different degrees of radial lengthening (0-1 mm, 0-3 mm, and 0-5 mm). Finally, anatomic dissections determined the presence of DOB in each sample. Radial lengthening did not correlate with decreased translation distance in machine-driven stress tests. There was a trend that greater radial lengthening appeared to reduce DRUJ translation distance in the presence of the DOB, but the power of the subgroup analysis was too limited to permit a statistical analysis. Radial lengthening did not demonstrate a benefit in improving DRUJ stability in a triangular fibrocartilage complex injury model. The presence of the DOB may influence the effectiveness of radial lengthening on DRUJ stability; however, further studies with larger samples are needed. This biomechanical study did not support radial lengthening in improving DRUJ stability. Surgeons should be cautious in using radial lengthening to treat DRUJ instability associated with acute distal radius fractures.