A handheld flexible manipulator system for frontal sinus surgery.

PURPOSE: Draf drainage is the standard treatment procedure for frontal sinus diseases. In this procedure, rigid angled endoscopes and rigid curved instruments are used. However, laterally located pathologies in the frontal sinus cannot be reached with rigid instrumentation. In order to assist surgeons with such complicated cases, we propose a novel handheld flexible manipulator system. METHODS: A cross section of 3 mm × 4.6 mm enables transnasal guiding of a flexible endoscope with 1.4 mm diameter and a standard flexible surgical instrument with up to 1.8 mm diameter into the frontal sinus with increased reachability. The developed system consists of an electrical discharge-machined flexure hinge-based nitinol manipulator arm and a purely mechanical handheld control unit. The corresponding control unit enables upward and left-right bending of the manipulator arm, translation, rolling, actuation and also quick exchange of the surgical instrument. In order to verify the fulfillment of performance requirements, tests regarding reachability and payload capacity were conducted. RESULTS: Reachability tests showed that the manipulator arm can be inserted into the frontal sinus and reach its lateral regions following a Draf IIa procedure. The system can exert forces of at least 2 N in the vertical direction and 1 N in the lateral direction which is sufficient for manipulation of frontal sinus pathologies. CONCLUSION: Considering the fact that the anatomical requirements of the frontal sinus are not addressed satisfactorily in the development of prospective flexible instruments, the proposed system shows great potential in terms of therapeutic use owing to its small cross section and dexterity.

Anatomical Characterization of Frontal Sinus and Development of Representative Models.

This paper presents the methods and the materials towards characterizing frontal sinus anatomy and developing representative anatomical models which reflect the variance of the anatomy with three different sizes: small, medium and large. Anatomical characterization was performed using computer tomography data of up to 50 anonymous patients. Dimensional and volumetric measurements were conducted using the .stl files generated by segmentation and 3-D reconstruction. Three representative data sets were chosen to be realized in the form of models with frontal sinuses of small, medium and large sizes. The models include bone, mucosa and skin structures, whereas bone structures were manufactured by selective laser sintering of polyamide and the soft tissues by casting of gelatin and silicone. To ensure realistic optical and mechanical properties of the mucosa, verification tests were performed and the results were integrated into the manufacturing process.

An Improved Instrument Table for Use in Functional Endoscopic Sinus Surgery.

BACKGROUND: The clinical motivation for the current study was that various instrument tables are located far away from the patient's head, and the only way for the surgeon to access an instrument is via a scrub nurse. Thus, the idea for this study was the development and evaluation of an improved and conveniently positioned instrument table. MATERIAL AND METHODS: An improved instrument table (IT) was designed, built, and tested. We assessed its use in 150 surgeries from 1 October 2013 to 30 June 2014 (group A), and another 150 surgeries without use of the IT from 1 February 2013 to 31 October 2014 as a control group (group B). RESULTS: With use of the improved IT during functional endoscopic sinus surgery (FESS), preparation-time was extended by 0.1 min and the SLOT-time was reduced by 19.6%. The number of different instruments (35.3%) used was reduced, as well as the number of manual interactions with instruments (7.8%) and the number of manual interactions with the scrub nurse (66.1%). In addition, the ergonomics with use of the IT improved by 40.0%. The only potential disadvantage was a reduction of working space and thereby a constraint of the scope. Compared to the benefits, this problem is minor. CONCLUSIONS: Conclusively, the improved IT is of value for everyday use in surgery and offers a great benefit for FESS, and may be useful in other kinds of surgery (e.g., duraplasty).