HEY PATRICIA--Check this out...maybe this is what he is talking about??
Computer-assisted surgery (CAS) is an adjunct process used in conjunction with certain orthopedic procedures. CAS encompasses both image-guided and imageless forms. Utilizing such tools as imaging, markers, reference frames, intraoperative sensing, and computer workstations, computer-assisted navigational procedures increase visualization of the surgical field and aid in precise navigation with minimally invasive approaches. CAS may involve guidance based on intraoperative images obtained by such means as fluoroscopy or ultrasound. It may also involve preoperative images or imageless navigation utilizing angles and measurements (kinematics) for anatomy determination. The key components of CAS include planning, registration, and navigation. Planning typically includes preoperative and/or intraoperative images taken by computed tomography, magnetic resonance, and/or fluoroscopy, and involves the creation of three-dimensional graphic models of the patient's anatomy. The patient-specific surgical plan and images are then used during surgery to guide the surgeon by combining these with intraoperative navigation capabilities. Optical targets, or trackers, such as digitizing or LED-equipped probes, are attached to points on the bone anatomy or to surgical tools. An optical camera tracks the position of these for accurate navigation and measurement in relation to any bone or instrument movement as the surgery is performed. The software in these navigational systems matches or "registers" the position of the patient on the operating table to the geometric description of the bony surface derived from the images already used to plan the surgery. Multiple images are simultaneously displayed on the monitor. The "virtual" tool trajectory that corresponds to the tracked tool movements is displayed over the previously saved views in real-time as the surgeon operates. Report 20985 for imageless CAS, 20986 for CAS with image guidance based on images obtained intraoperatively, and 20987 for those obtained preoperatively.~ ~~. ~~