Abstract
Wireless technologies applied to the medical field have grown both in prevalence and importance in the past decade. Various applications and technologies exist underneath the telemedicine umbrella including Point-of-Care systems where electrocardiographs, blood pressure, temperature, and medical image data are recorded and transmitted wirelessly, which enables remote patient monitoring from inside hospitals, personal residences, and virtually any location with access to satellite communication. Another widespread application for wireless systems in hospitals is asset tracking, typically done with RFID technology. Wireless technologies have not been widely used in computer assisted orthopaedic surgery (CAOS) because of the limitations in terms of overall 3-D accuracy.
We have developed a wireless positioning system based on ultra wideband technology (UWB) which achieves mm-range 3-D dynamic accuracy and can be used for intraoperative tracking in CAOS systems. Current intraoperative tracking technologies include optical and electromagnetic tracking systems. The main limitations with these systems include the need for line-of-sight in optical systems and the limited view volume and susceptibility to metallic interference in electromagnetic tracking systems. UWB indoor positioning does not suffer from these effects. Until this point, the main limitation of UWB indoor positioning systems was its limitation in 3-D real-time dynamic accuracy (10–15 cm as opposed to the required 1–2 mm).
We have developed a UWB indoor positioning system which achieves dynamic 3-D accuracy in the range of 5–6 mm for a non-coherent approach and 0.5–1 mm for a coherent approach (transmitter and receiver use the same clock signal). The integration of this tracking system with smart surgical tools opens up a plethora of exciting intraoperative applications including picking landmarks, 3-D bone and instrument registration, real-time wireless pressure sensing used for ligament balancing in TKA, and real-time A-mode ultrasound bone morphing. The UWB tracking system will be presented along with its integration into smart surgical tools and surgical navigation.
Correspondence should be addressed to Diane Przepiorski at ISTA, PO Box 6564, Auburn, CA 95604, USA. Phone: +1 916-454-9884; Fax: +1 916-454-9882; E-mail: ista@pacbell.net