Computed tomographic assessment of reduction of the distal radioulnar joint by gradual lengthening of the radius.

Congruency of the distal radioulnar joint was assessed by computed tomography after gradual lengthening of the radius in patients with considerable ulnar positive variance of mean 12 (range 10-17) mm and chronic dislocation of the distal radioulnar joint. Six patients of mean age 25 years were treated by radial osteotomy and subsequent gradual lengthening using either a single-rod or a half-ring external fixator, which was applied for a mean of 81 days. The causes of deformity were distal radial epiphyseal injury in four, malunion of a radius shaft fracture in one and Madelung deformity in one. Computed tomography scans taken at 1 year postoperatively demonstrated that all patients had a congruent distal radioulnar joint. All patients achieved symptom and radiographic parameter improvements at a mean follow-up of 40 months. A disadvantage was unattractive scars on a cosmetically important surface of the forearm. Given a relatively intact bony contour of the distal radioulnar joint, congruent reduction of the distal radioulnar joint can be obtained by gradual lengthening of the radius.