NOFUSS: Navigated Orthopaedic Fixation using Ultrasound System

Fractures of the sacroiliac joint often require treatment through internal fixation. This procedure is typically guided by the use of intraoperative fluoroscopy, using an untracked C-arm device. However, this involves ionizing radiation exposure and the possibility of screw malplacement. We introduce the Navigated Orthopaedic Fixation using Ultrasound System (NOFUSS): an ultrasound (US) based end-to-end system for providing real-time navigation for iliosacral screw (ISS) insertions. Our system consists of an US imaging device and an optical tracking camera, together with computational algorithms for automatic processing of intraoperative data. In a cadaver trial of 6 specimens, we found that the ISS insertions performed using NOFUSS demonstrated accuracy comparable to conventional fluoroscopy guidance in the three specimens for which we could obtain good ultrasound images, reduced insertion time, and required no ionizing radiation.