Modified fluoroscopic imaging technique for the central screw placement in percutaneous screw fixation of scaphoid fracture.

BACKGROUND

: The fluoroscopic imaging technique that has been used in the dorsal percutaneous screw fixation of scaphoid fracture was modified for more consistent central screw placement according to the different fracture locations.

METHODS

: Eighteen scaphoids of the fresh-frozen cadaver were used. The computed tomographic data of scaphoid were reconstructed for 3D images. The reconstructed image was three dimensionally rotated to define the outlining images of scaphoid according to the three imaginary fracture lines (proximal 1/3, waist, distal 1/3). Two dimensional plain radiographic images were taken based on the 3D image to show the overlapping shapes of outer cortical lines of proximal and distal scaphoid. Under the fluoroscopic guidance, guide wire was inserted after the previously obtained 2D images. To verify the accuracy of fluoroscopic guidance for the fixation, the scaphoid was cut through each fracture plane and central position of each guide wire was analyzed.

RESULTS

: For the proximal 1/3 fracture, the proximal cortical line was positioned on the radial side to the distal cortical line. For the waist fracture, two cortical shadows were eclipsed and for the distal 1/3, proximal cortical line was positioned ulna side to the distal cortical line. The cut surface analysis revealed statistically significant results of central guide wire placement for each fracture plane.

CONCLUSIONS

: The fluoroscopic images should be individualized according to the fracture planes for more consistent and accurate central guide wire placement in the dorsal percutaneous screw fixation of scaphoid fracture.