Accuracy of computer-assisted surgery

Computer-assisted surgery was introduced to improve the performance of surgical interventions with electronic instruments and software. Total knee arthroplasty (TKA) in combination with development in robotic-assisted surgery, surgical navigation was primarily exploited and introduced, essentially for improving the accuracy of implant positioning [4]. The main advancement pursued is an ‘augmented reality’ in the operating theatre, made up of a number of digital cameras and trackers attached to the bones and to the standard instrumentation. Information such as optimal resection planes and targeted limb alignment is displayed to the surgeon during the operation before performing bone preparation, also according to a surgeon’s specific preference (posterior slope, femur flexion, bone resections, varus/valgus, joint line, etc.). This tracking is usually obtained by means of a stereophotogrammetric system made of digital cameras and emitting or reflective markers. Another series of navigation systems for TKA are based on electromagnetic tracking devices, not the topic of this present chapter, for which specific information can be found elsewhere [34, 74]. In general, the surgical navigation systems are meant to enhance the final positioning of the implant (accuracy), as well as the visibility in inaccessible areas (security), and the prediction of the effects of the surgical actions (control).