title: The navigation-controlled drill in temporal bone surgery: a feasibility study.
abstract: BACKGROUND
  This study examines the feasibility of a navigation-controlled (NC) drill for surgery on the petrosal bone in an experimental environment. According to the principle of NC, the drill is to be switched off automatically once the borders of the workspace are exceeded during a mastoidectomy.
  
  
  METHODS
  The registration is based on an optical navigation system with navigation software (MiMed). As surgery engine, the Unidrive-system (Karl Storz GmbH & CO. Kg, Tuttlingen, Germany) was integrated. The definition of the workspace was performed manually in axial computed tomography (CT) slices of the petrosal bone phantom. The mastoidectomy on the model was accomplished in three runs with 10 trial surgeons altogether (5 experienced [exp.] in otologic (ear) surgery, 5 inexperienced [nonexp.]). During each run, the following were logged: the total length of time for the procedure as well as the number and extent of injuries to the risk structures (facial nerve, horizontal semicircular canal, sigmoid sinus). The resultant petrosal bone cavities were measured on the CT.
  
  
  RESULTS
  The time for the segmentation of the workspace for the mastoidectomy amounted to 17 minutes. The mean value of the drilling (e.g., milling) performance ranges from 6.61 mm3/s (group 1 [nonexp. + NC]), 9.62 mm3/s (group 2 [exp. w/o NC]), to 10.08 mm3/s (group 3 [exp. + NC]). The relative deviation to the segmented volume amounts to +7.4% (794.3 mm3) for group 1, -39.9% for group 2, and -34% (3,647.0 mm3) for group 3. In the groups with NC guidance of the drill, no damage to a risk structure could be logged. In the group of exp. ear surgeons without NC assistance, one injury to the facial nerve in the petrosal bone phantom occurred.
  
  
  CONCLUSIONS
  The results that follow prove the fundamental feasibility of an NC drill for surgery of the petrosal bone using the example of the simple mastoidectomy in the laboratory test. When using NC, tissue resection is faster, more precise, and has fewer related complications than the same procedure without. The results offer a very promising basis for the introduction of a newly conceived system to the procedure of NC surgery on the petrosal bone. The device configuration used here was originally conceived for NC guidance of a shaver in functional endoscopic sinus surgery. Individual errors will have to be mitigated through the new version of the control unit presently in development.
authors.affiliation: Department of ENT, University Hospital Leipzig, Leipzig, Germany. Gero.Strauss@medizin.uni-leipzig.de
authors.forename: Gero
authors.initials: G
authors.lastname: Strauss
authors.forename: Kirill
authors.initials: K
authors.lastname: Koulechov
authors.forename: Mathias
authors.initials: M
authors.lastname: Hofer
authors.forename: Elmar
authors.initials: E
authors.lastname: Dittrich
authors.forename: Ronny
authors.initials: R
authors.lastname: Grunert
authors.forename: Hendrick
authors.initials: H
authors.lastname: Moeckel
authors.forename: Eva
authors.initials: E
authors.lastname: Müller
authors.forename: Werner
authors.initials: W
authors.lastname: Korb
authors.forename: Christos
authors.initials: C
authors.lastname: Trantakis
authors.forename: Thomas
authors.initials: T
authors.lastname: Schulz
authors.forename: Juergen
authors.initials: J
authors.lastname: Meixensberger
authors.forename: Andreas
authors.initials: A
authors.lastname: Dietz
authors.forename: Tim
authors.initials: T
authors.lastname: Lueth
mesh_terms: D005240:Feasibility Studies; D006801:Humans; D066298:In Vitro Techniques; D008328:Man-Machine Systems; D008416:Mastoid / Q000000981:diagnostic imaging / Q000601:surgery*; D019060:Minimally Invasive Surgical Procedures / Q000379:methods*; D008953:Models, Anatomic; D013517:Otorhinolaryngologic Surgical Procedures / Q000379:methods*; D012371:Robotics; D025321:Surgery, Computer-Assisted / Q000295:instrumentation*; D014057:Tomography, X-Ray Computed