Intraoperative Tilted Posteroanterior View for the Measurement of Distal Radius Articular Step-Off.

The purpose of this study is to more accurately determine distal radius articular step-off in the posteroanterior (PA) view. A cadaveric forearm was osteotomized with varying amounts of articular displacement. A second osteotomy was made through the distal radius metaphysis to create four positions of tilt in the lateral plane (5° and 15° dorsal tilt; 5° and 15° volar tilt). Using fluoroscopy, the beam was positioned in the lateral plane from 25° volar to 20° dorsal, separated by 5° increments, obtaining modified PA images of the distal radius in its various configurations. The images were randomly evaluated for step-off by three hand surgeons in a blinded fashion. Statistical analysis was performed to determine the accuracy between estimated and actual step-off and was demonstrated to be greater when the PA view was parallel to the distal radius tilt in the lateral plane, for all four configurations of distal radius tilt. Data pertaining to the distal radius with 0 mm of step-off did not demonstrate the PA view, parallel to the distal radius tilt, to be superior than the PA views not parallel to the tilt; reaffirming that with anatomic reduction, any fluoroscopic image exhibits good alignment. This study confirms that the most accurate method of accessing PA step-off is to first determine the tilt of the radius on a lateral film and then align the beam in the PA plane to match this tilt.