An image fusion system for corrective osteotomy of distal radius malunion

Abstract

Background: To provide surgical support for corrective osteotomy, we developed an image fusion system for three-dimensional (3D) preoperative planning and fluoroscopy. To assess the utility of this image fusion system, we evaluated the reproducibility of preoperative planning for corrective osteotomy of dorsally angulated distal radius malunion using the system and compared reproducibility without using the system.

Methods: Ten wrists from 10 distal radius malunion patients who underwent corrective osteotomy were evaluated. 3D preoperative planning and the image fusion system were used for the image fusion group (n = 5). Only 3D preoperative planning was used for the control group (n = 5). 3D preoperative planning was performed for both groups in order to assess reduction, placement, and the choice of implants. In the image fusion group, the outline of the planned image was displayed on a monitor and overlapped with fluoroscopy images during surgery. Reproducibility was evaluated using preoperative plan and postoperative 3D images. Images were compared with the 3D coordinates of the radial styloid process (1), the volar and dorsal edges of the sigmoid notch (2) (3), and the barycentric coordinates of the three reference points. The reproducibility of the preoperative plan was evaluated by the distance of the coordinates between the plan and postoperative images for the reference points.

Results: The distances between preoperative planning and postoperative reduction in the image fusion group were 2.1 ± 1.1 mm, 1.8 ± 0.7 mm, 1.9 ± 0.9 mm, and 1.4 ± 0.7 mm for reference points (1), (2), (3), and the barycenter, respectively. The distances between preoperative planning and postoperative reduction in the control group were 3.7 ± 1.0 mm, 2.8 ± 2.0 mm, 1.7 ± 0.8 mm, and 1.8 ± 1.2 mm for reference points (1), (2), (3), and the barycenter, respectively. The difference in reference point (1) was significantly smaller in the image fusion group than in the control group (P < 0.05).

Conclusion: Corrective osteotomy using an image fusion system will become a new surgical support method for fracture malunion. Trial registration Registered as NCT03764501 at ClinicalTrials.gov.

Keywords: Computed tomography; Corrective osteotomy; Distal radius malunion; Fluoroscopy; Image fusion; Preoperative plan.

Conflict of interest statement

No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. The image fusion system described in the present study has been developed through a collaborative study between Tokyo Medical University Ibaraki Medical Center and LEXI Co., Ltd.

Figures

Fig. 1

Results of correction accuracy for reference points. a Results for each reference point. Ref (1): the radial styloid process, Ref (2): the sigmoid notch volar edge, Ref (3): the sigmoid notch dorsal edge. (b) Results for the barycenter of the three reference points. Blue bars indicate distances between preoperative planning and postoperative reduction in the image fusion group. Orange bars indicate distances between preoperative planning and postoperative reduction in the control group. *: P = 0.03, n.s.: not significant

Fig. 2

Results of correction accuracy for 3DRI and 3DVT. Blue bars indicate differences between preoperative planning and postoperative reduction in the image fusion group. Orange bars indicate distances between preoperative planning and postoperative reduction in the control group. n.s.: not significant

Fig. 3

Preoperative image of plate placement. An image of plate placement was created by calculating the correction angle required to restore volar tilt, radial inclination, and rotational deformation. The plate was placed so that the distal margin was parallel to the articular surface. An image of each frame shows the plate fixed to the distal radius. The blue dotted line on the frame (a) shows the correction angles for the coronal view. The blue dotted line on the frame (b) shows the correction angles for the sagittal view. The blue dotted line on the frame (c) shows the correction angles for the axial view

Fig. 4

Preoperative image of reduction. After separating the distal part of the radius, reduction was achieved by fixing the proximal side of the plate to the radius shaft. The gap between the distal and proximal parts of the radius indicates the predicted bone defect. a Coronal view, b sagittal view, c axial view

Fig. 5

Fusion image of the preoperative plan and fluoroscopy for plate placement. Based on the plate placement image, a contour extraction image was created and displayed on the fluoroscopy image for surgery. The plate was placed to fit the contour line. a Anterior–posterior view, b lateral view. * shows temporary fixing wires

Fig. 6

Fusion image of the preoperative plan and fluoroscopy for reduction. Based on the reduction image, the distal fragment was repositioned by adapting the proximal side of the volar locking plate to the contour extraction image

Fig. 7

Example images of 3D reference points. a An example image for each reference point. Left row images show the reference points in the preoperative plan image. Right row images show the reference points in the postoperative image. The light blue bar indicates the long axis of the distal radius. Red dots indicate the radial styloid process: reference point (1), the sigmoid notch volar edge: reference point (2), the sigmoid notch dorsal edge: reference point (3), and the barycentric coordinates. b An example image for 3DVT and 3DRI. The angle between a connecting line from reference point (2) to reference point (3) and a line perpendicular to the longitudinal axis of the radius was measured as the volar tilt on a 3D image in the sagittal view (3DVT). The angle between a line from reference point (1) to reference point (2) and a line perpendicular to the longitudinal axis of the radius was measured as the radial inclination on a 3D image in the coronal view (3DRI). The measured angles in the example image were 19.2° and 12.7° for 3DRI and 3DVT, respectively