Determining the optimal radiologic wrist and forearm position to visualize screw protrusion in scaphoid fixation.

Abstract

BACKGROUND: Surgical fixation of scaphoid fractures may result in unrecognized screw protrusion and subsequent cartilage damage to the adjacent joints. The purpose of this study was to use a three-dimensional (3D) scaphoid model to determine the wrist and forearm positioning that will allow intra-operative fluoroscopic visualization of screw protrusions. METHOD(S): Two 3D scaphoid models, with the wrist in neutral and 20degree ulnar deviated, were reconstructed from a cadaveric wrist using the Mimics software. The scaphoid models were divided into three segments and further divided into four quadrants in each of the three segments along the scaphoid axes. Two virtual screws, with a 2 and 1mm groove from the distal border, were placed so that the screws protrude from each quadrant. The wrist models were rotated along the long axis of the forearm and the angles at which the screw protrusions were visualized were recorded. RESULT(S): One-millimetre screw protrusions were visualized at a narrower range of forearm rotation angles compared to 2mm screw protrusions. One-millimetre screw protrusions in the middle dorsal ulnar quadrant could not be detected. Visualization of the screw protrusion in each quadrant varied with forearm and wrist positioning. CONCLUSION(S): In this model, all screw protrusions, except 1mm protrusions in the middle dorsal ulnar quadrant, were visualized with the forearm in pronation, supination or in the mid-pronation position and with the wrist in neutral or 20degree ulnar deviated.Copyright © 2023 The Authors. ANZ Journal of Surgery published by John Wiley & Sons Australia, Ltd on behalf of Royal Australasian College of Surgeons.