[Evaluation of a daily used navigation system for FESS]. / Untersuchungen zur Effizienz eines Navigationssystems für die HNO-Chirurgie: Auswertungen von 300 Patienten.

PROBLEM: The aim of this study is to proof the clinical efficiency by using a modern navigation system for Functional Endoscopic Sinus Surgery (FESS). MATERIAL AND METHODS: An optical navigation system was used in clinical routine of 300 patients. Two groups with 150 patients each were examined. Group A was treated with navigation assistance (Karl Storz Navigation Panel Unit NPU), Group B was treated without navigation by conventional FESS. Examination period was limited to 12 months. Median follow-up is 22 and 26 weeks. Perioperative, intraoperative and postoperative parameters were recorded by workflow-analysis, clinical and radiological findings and standardized questionnary. RESULTS: Application of the navigation system needs 1.1 min additional perioperative time in average. Intraoperative time reduction by the navigation system was about 10 min per case (Group A 32.6 (SD 11.2) min, Gruppe B 42.7 (SD 9.5) min). Specific information by the navigation system was evaluated in all surgical areas as usefull and additional to a-priori-knowledge. Postoperatively patients from group A (10/89) show lower rate of re-polyposis then in group B (24/71). Fenestration of the sphenoid sinus were sufficient by CT-evaluation in 100% (group A) and 23% (group B). CONCLUSIONS: The advantages of the examined navigation system in comparison to the gold standard of FESS are proven. Navigation assistance led to an reduced intraoperative time consumption, increased postoperative results and lowered the workload of the surgeons.

[Improved accuracy and precision of the automated shaver (navigated control) in functional endoscopic sinus surgery]. / Verbesserte Umsetzung der Resektionsgrenzen in der Nasennebenhöhlenchirurgie mit dem navigiert-kontrollierten Shaver.

BACKGROUND: The feasibility of a navigate-controlled Shaver for the paranasal sinus surgery was proven in an initial study. Deficits showed up in the conversion of the planed cavity. Goal of this study is (1) the development and evaluation of a FESS demonstrator for the investigations to the surgical accuracy and (2) the evaluation of the resulting surgical accuracy for registration and conversion of the work space with an improved rigidity of the Shaver and a completely revised study design. METHODS: As a demonstrator for the navigate-controlled resection of a volume through the Shaver a two-piece plastic head with an anatomical head and soft tissue model was designed. The investigation of the surgical accuracy takes place with 417 measurements to 4 different fiducial markers on the demonstrator head. The measurements for the deviation of the resulting cavity from the planned volume was realised with a work space by 24 x 24 x 30 mm. The 5 walls of the cavity were seized with 80 measuring points for each level and thus altogether 2000 measured values (5 models x 5 levels x 200 points). RESULTS: The described demonstrator showed itself suitable for the close-to-application attempts to the surgical accuracy. The maximum deviation A (max) indicated position of the Shaver from the reference value amounted to 1,93 mm. The maximum average value of the exceeding of a planned cavity amounts to 1,62 mm. CONCLUSIONS: Based on these results a virtual safety passage of 2.00 mm is sufficient. The study refers the clinical serviceability of the navigate-controlled Shaver in paranasal sinus surgery.