title: A state of the art review and categorization of multi-branched instruments for NOTES and SILS.
abstract: BACKGROUND
  Since the advent of Natural Orifice Translumenal Endoscopic Surgery (NOTES) and single incision laparoscopic surgery (SILS), a variety of multitasking platforms have been under development with the objective to allow for bimanual surgical tasks to be performed. These instruments show large differences in construction, enabled degrees of freedom (DOF), and control aspects.
  
  
  METHODS
  Through a literature review, the absence of an in-depth analysis and structural comparison of these instruments in the literature is addressed. All the designed and prototyped multitasking platforms are identified and categorized with respect to their actively controlled DOF in their shafts and branches. Additionally, a graphical overview of patents, bench test experiments, and animal and/or human trials performed with each instrument is provided.
  
  
  RESULTS
  The large range of instruments, various actuation strategies, and different direct and indirect control methods implemented in the instruments show that an optimal instrument configuration has not been found yet. Moreover, several questions remain unanswered with respect to which DOF are essential for bimanual tasks and which control methods are best suited for the control of these DOF.
  
  
  CONCLUSIONS
  Considering the complexity of the currently prototyped and tested instruments, future NOTES and SILS instrument development will potentially necessitate a reduction of the available DOF to minimize the control complexity, thereby allowing for single surgeon bimanual task execution.
authors.affiliation: Bio-Inspired Technology Group, Biomechanical Engineering Dept., Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Mekelweg 2, 2628 CD, Delft, The Netherlands, E.A.Arkenbout@tudelft.nl.
authors.forename: Ewout A
authors.initials: EA
authors.lastname: Arkenbout
authors.forename: Paul W J
authors.initials: PW
authors.lastname: Henselmans
authors.forename: Filip
authors.initials: F
authors.lastname: Jelínek
authors.forename: Paul
authors.initials: P
authors.lastname: Breedveld
mesh_terms: D000818:Animals; D004867:Equipment Design; D006801:Humans; D010535:Laparoscopy / Q000295:instrumentation*; D057605:Natural Orifice Endoscopic Surgery / Q000295:instrumentation*