Fluoroscopy as an Imaging Means for Computer-Assisted Surgical Navigation

Abstract

Objective: Intraoperative fluoroscopy is a valuable tool for visualizing underlying bone and surgical tool positions in orthopedic procedures. Disadvantages of this technology include the need for continued radiation exposure for visual control, and cumbersome means of alignment. The purpose of this article was to highlight a new concept for a computer-assisted freehand navigation system that uses single intraoperatively acquired fluoroscopic images as a basis for real-time navigation of surgical tools

Materials and Methods: Optoelectronic markers are placed on surgical tools, a patient reference, and the fluoroscope to track their position in space. Projection properties of the fluoro-scope are acquired through an initial precalibration procedure using a tracked radiopaque phantom grid. Corrections are applied to compensate for both the fluoroscope's image intensifier distortions and the mechanical bending of the C-arm frame. This enables real-time simulation of surgical tool positions simultaneously in several single-shot fluoroscopic images. In addition, through optoelec-tronically tracked digitization of a target viewpoint, the fluoroscope can be numerically aligned at precise angles relative to the patient without any X-ray exposure

Results: This article shows the feasibility of this technology through its use in cadaver trials to perform the difficult task of distal locking of femoral nails.

Key Words:

• C-arm
• fluoroscopic image registration
• computer-integrated surgery
• distal locking
• femoral nail