Image Fusion for Intraoperative Control of Axis in Long Bone Fracture Treatment

Abstract Background: The incidence of malalignment after long bone fracture fixation is reported to be between 0 and 37%. Modern fracture treatment strives towards closed reduction and minimally invasive fracture fixation, thus not exposing the fracture itself. Hence, the occurrence of malalignment might even be higher than previously reported and quite frequently even necessitate secondary operations. Minimally invasive techniques rely heavily on intraoperative fluoroscopy. However, fluoroscopic images have small cross-sections and consequently limit intraoperative visualization of the limb to individual segments only. Under these circumstances, correct alignment of fragments in long bone fractures is often compromised. Methods: We present a new software prototype using an absolute reference panel to concatenate two or more discontinuous fluoroscopic images into one single panoramic picture. The reference panel is placed on the operating table under the limb to be examined. Prior to digital picture fusion, the software applies non-linear distortion, picture scaling and de-rotation algorithms to the fluoroscopic images. Results: The presented software runs on a notebook and processes images generated by a commercially available mobile C-arm within seconds. The reliability of alignment in the panorama picture is found to be numerically adequate and the technique appropriate for clinical use. Conclusion: This method aims to improve the intraoperative visualization in minimally invasive osteosynthesis and therefore diminish malalignments in long bone fracture treatment.