Grundlagen der 3D Navigation

Introduction

Application of computer technology in cranio-maxillofacial surgery opened new perspectives in preoperative planning and accurate intraoperative realization of treatment concepts. To simulate the postoperative outcome the treatment plan is based on 3D visualization of radiological data. The transmission of digital imaging data and the corresponding treatment plan via telecommunication was a milestone in the emerging field of telemedicine.

With ubiquitous availability of high speed transmission researchers have gotten more insight into the feasibility of communication technology for diagnosis and care delivery. In the case of image guided surgery (IGS) the preoperative 3D simulation combined with the real-time display of the virtual instrument 3D position relatively to the patient’s anatomy guides the surgeon during surgery. In conventional consultation the physician applies the senses of sight and touch to make a diagnosis and develop a treatment plan.

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There is evidence that some inconsistencies in the appraisal of IGS can be contributed to spatial disorientation (Lit [i] ) interpreting or verifying radiological data in intraoperative context. A treatment plan based on radiological imaging modalities only therefore puts a remote expert even more at risk of misjudgement.

[i] Disorientation in Minimal Access Surgery: A Case Study

Cao, Caroline G.L.; Milgram, Paul

Human Factors and Ergonomics Society Annual Meeting Proceedings, Proceedings 4

Medical Systems and Rehabilitation , pp. 169-172(4)


TEST

Our solution is to develop a navigation system that references not to computer tomography (CT), to structures that are normally invisible to the human eye, but primarily to structures directly visibly to the human sight during any stage of the surgical procedure. In the case of maxillofacial surgery this is the 3D topography of the dentition and upper and lower jaw, as well as the 3D face surface. This eliminates ambiguity in interpreting the intraoperative accuracy of the system, and for the remote expert the additional information comes close to the sense of touch. The evolution of dental implant planning from bone centric planning based on radiological data to dentition backward planning was a paradigm shift. The integration of soft tissue surface data acquired independently of the CT allows us to take this one step further by comparing different facial mimic states (smile and non smile) to improve the quality of the simulation. The treatment plan also comprises functional information of the temporomandibular joint as it has a mentionable impact on the occlusion and the biomechanical load (Lit [i] ) and takes into account the final aesthetical outcome that is of paramount importance for the patient.


 

Wagner et al. Augmented reality environment for temporomandibular joint motion analysis. The International journal of adult orthodontics and orthognathic surgery (1996) vol. 11 (2) pp. 127-36