Many navigation (Image Guided Surgery or IGS) systems are keyed to safely and accurately placing implants into complex anatomy. In spine surgery such as disc arthroplasty and fusion surgery this can be extremely helpful. Likewise, in joint arthroplasty the accurate placement with respect to the operative plan is widely recognized to be of benefit to long term results. However, where realignment of anatomy is desired following implant placement, such as in high tibial osteotomy, spinal fusion with correction of deformity, and spinal disc arthroplasty, navigation systems can tell you where you are, but not where you would like to be. We have developed specific software modification technology, applicable to all current navigation systems that addresses this need for assistance in surgical correction of anatomy to a desired alignment without the requirement for further imaging or irradiation. The benefits of our software allow image free re-referencing of image guided surgery, accommodation of intra-operative changes in anatomy, and intra-operative accountability and adjustment to allow errors of image guidance to be identifiable and correctible, at any stage of image guided surgery. This software allows accurate pre-operative planning, intra-operative verification and assessment of the operative plan, and actual outcomes of the surgery to be assessed as the surgery is performed. It allows the surgeon to subsequently verify if the operative planning has been adequately achieved, and if not can verify if continued surgery has then achieved the planning goals. This verification and image guidance does not require further imaging during surgery, relying upon the original data set and software enhancements.
Image guided surgery (IGS), or “Navigation,” is now widely used in many areas of surgery including arthroplasty. However, the options for establishing, in real time, the veracity of the navigation information are limited. Manufacturers recommend registering with a “prominent anatomical feature” to confirm accurate navigation is being presented. In their fine print, they warrant the accuracy proximate to the navigation array attached to the body. In multi-level spine surgery where it is most sorely needed, this limits the warrants to the vertebra of reference array attachment. In arthroplasty surgery, the accuracy of the system can be erroneous through technical errors and a delay may occur prior to verification of such innacuracy. In response to this situation surgeons have taken to using K-wires, FaxMax screws and a variety of other “Fiducial Markers”, but these were not specifically designed for this purpose and in many ways are inadequate for the task of verification of navigation accuracy. We have developed a fiducial marker that is designed to address these unmet needs. The Precision Screw is clearly visible on imaging modalities and the central registration point is identifiable at any angle of viewing, with accuracy of fractions of a millimeter. It does not interfere with surgery, being low profile and securely fixed to bone. Finally, in use, it is secure in capturing the navigation probe so that the surgeon does not need to focus on keeping the probe located while reviewing the navigation data. We believe these features make this a useful and worthwhile addition to IGS.
