title: Smart bioimpedance-controlled craniotomy: Concept and first experiments.
abstract: Craniotomy is part of many neurosurgical interventions to create surgical access to intracranial structures. The procedure conventionally bears a high risk of unintended dural tears or damage of the soft tissue underneath the bone. A new synergistically controlled instrument has recently been introduced to address this problem by combining a soft tissue preserving saw with an automatic cutting depth control. Many approaches are known to obtain the information required on the local bone thickness. However, they suffer from unsatisfactory robustness against disturbances occurring during surgery and many approaches require additional intra- or preoperative steps in the workflow. This article presents first concepts for real-time cutting depth control based on in-process bioimpedance measurements. Furthermore, sensor integration into a synergistic surgical device incorporating a bidirectional oscillating saw is demonstrated and evaluated in first feasibility tests on a fresh bovine bone specimen. Results of bipolar measurements show that the transition of different layers of bicortical bone and bone breakthrough lead to characteristic impedance patterns that can be used for process control.
authors.affiliation: 1 Chair of Medical Engineering, RWTH Aachen University, Aachen, Germany.
authors.forename: Annegret
authors.initials: A
authors.lastname: Niesche
authors.affiliation: 1 Chair of Medical Engineering, RWTH Aachen University, Aachen, Germany.
authors.forename: Meiko
authors.initials: M
authors.lastname: Müller
authors.affiliation: 1 Chair of Medical Engineering, RWTH Aachen University, Aachen, Germany.
authors.forename: Fritz
authors.initials: F
authors.lastname: Ehreiser
authors.affiliation: 2 Philips Chair for Medical Information Technology, RWTH Aachen University, Aachen, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Teichmann
authors.affiliation: 2 Philips Chair for Medical Information Technology, RWTH Aachen University, Aachen, Germany.
authors.forename: Steffen
authors.initials: S
authors.lastname: Leonhardt
authors.affiliation: 1 Chair of Medical Engineering, RWTH Aachen University, Aachen, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Radermacher
mesh_terms: D000465:Algorithms; D003399:Craniotomy / Q000295:instrumentation / Q000379:methods*; D017097:Electric Impedance; D004867:Equipment Design; D020342:Finite Element Analysis; D013997:Time Factors
keywords: Bioimpedance; bone cutting; computer-assisted surgery; craniotomy; impedance-controlled surgical instrumentation; robot-assisted surgery; skull trepanation