[Instrument navigation in ensonasal sinus surgery]. / Instrumentennavigation in der endonasalen Stirnhöhlenchirurgie: Gibt es eine Operation unter "reiner Navigationsführung"?

BACKGROUND: It is to be expected that, microsurgical operations in ENT must be partially performed without direct vision, e. g. without the possibility of controlling the preparation progress. This study provides a clinical example of how instrument navigation may be used in a safe and reasonable manner to the benefit of treatment quality. It is assumed that a median frontal sinus drainage procedure may be performed by means of a tracked sinus drill using solely instrument navigation. MATERIAL AND METHODS: The sinus drill was registered using an optoelectric navigation system. An optical registration device was attached to the drill. In the period from 1 December 2011 to 30 April 2012 (5 months) 24 patients underwent a median frontal sinus drainage. 12 of the surgeries were performed under the condition operation navigation. The other 12 surgeries were performed using solely instrument navigation. RESULTS: When applying mode Instrument Navigation (IN), a significantly reduced incision-to-suture time was registered within both groups. Within the group Draf IIB, it was reduced to 68.5% (from 67.1 min to 46.0 min). Resection efficiency, i. e., the ratio between the width of the frontal sinus ostium and the required total surgery time, widely differed to the benefit of group IN. Within both groups, the questionnaire revealed a high level of confidence in Surgical Management and Guidance Systems (SMGS) functionalities (100%). CONCLUSION: The present study was designed to show for the first time a median frontal sinus drainage under the condition solely instrument navigation.

[The 'Surgical Deck': a new generation of integrated operational rooms for ENT]. / Das "Surgical Deck": Eine neue OP-Generation für die HNO-Chirurgie.

BACKGROUND: Existing operating room concepts do not meet modern technological opportunities anymore. The "Surgical Deck" is supposed to represent a prototype for a new operating room generation. The objective of the project is to achieve a better integration of functions and to develop an innovative concept for a highly developed surgical workstation. MATERIAL AND METHODS: 3 working areas are defined: Surgical, Airway and Technical Cockpit. The evaluation was conducted on 284 surgeries carried out from 01.08. 2011 to 31.01. 2012. The evaluation team consisted of 6 surgeons, 3 surgery nurses, 3 anesthesiologists and 4 anesthesia nurses. Within a detailed analysis, the data of 50 FESS surgeries were compared to those of a control group. RESULTS: Within the FESS group, the average slot time was reduced by 13%. 88.2% of those questioned assessed ergonomics as being better than in the conventional OR. 71.5% stated that the Surgical Deck provided an added value with regard to the surgical procedure. 91.3% confirmed that the system control required additional training. 79.3% described the cost-benefit-ratio as appropriate. For 96% of the surgeries, respondents said that they were feeling adequately supported by the technology. CONCLUSION: The results show a clear advantage of the system architecture. The Surgical Deck may present a solid foundation with regard to the transfer of the system into the clinical practice. This is relevant for new assistance functions such as process control software or navigation-based collision warning systems. It is to be expected that the project will significantly contribute to further develop the future surgical workstation and its standardization.

[A surgical micromanipulator in ear surgery: potential and comparison to freehand preparation]. / Ein chirurgischer Mikromanipulator in der Ohrchirurgie: Potenzial und Vergleich mit der freien Präparation.

INTRODUCTION: Surgical accuracy in microscopic ear surgery is reduced by limited access and tremor. At this point a micromanipulator could have a positive influence. The goal of the study was: 1. To develop a system that would enable measurements of accuracy, time and precision during a manual approach to the middle ear 2. To apply a manipulator that can easily be a compact part of the regular setup in ear surgery 3. To compare the manual results critically considering accuracy and tremor reduction and to compare these results with those of a manipulator A manipulator in ear surgery does not need to be a highly complex structure with force feedback and multiple degrees of freedom. The surgeon's preparation in middle ear surgery is most of the time straight without potentially applying the 15 degrees of freedom the human hand can offer. The micromanipulator in this study was developed in order to serve as a compact, teleoperated instrument without limiting the surgeon's dexterity. The use of standard instruments facilitates the integration of the system in existing surgical procedures and sterilisation concepts. MATERIAL AND METHODS: Ten head and neck surgeons simulated an approach to the stapedial footplate on a modified 3D cast of a realistic human skull in an experimental OR. A perforator was moved to a reference point on the stapedial footplate. The movements were detected by means of an image acquisition system. Each trial was repeated more than 200 times, aiming both manually and with the aid of a micromanipulator (> 4,000 measurements). RESULTS: Accuracy for the manual and micromanipulator approach revealed no considerable differences. In absolute terms, the manual approach was more accurate. However, the learning curves indicated a stronger decrease in deviation when the micromanipulator was used and also less deviation in scatter plots. At the beginning, the time required for pointing increased when using the micromanipulator, but decreased to a greater extent in the course of the trial when compared to the manual approach. The work strain was distinctively lower when the micromanipulator was applied. CONCLUSION: The micromanipulator gave evidence of a stronger effect as regards individual improvement in accuracy and time span. The micromanipulator shows potential for improvements in accuracy as well as compensation for poor ergonomics.

[First clinical experiences with an endoscope manipulator system in endo- and transnasal surgery]. / Klinischer Einsatz eines Endoskop-Manipulator-Systems in der endo- und transnasalen Chirurgie.

BACKGROUND: Endo- and transnasal surgery needs optical support. The use of a microscope allows bimanual manipulation. More often the endoscopic technique is used which needs one hand for endoscope guidance "loosing" it for manipulation or demanding an assistant for endoscope guidance. In this work the use of a miniature endoscope manipulator system for endonasal and transnasal surgery was evaluated. MATERIAL AND METHODS: 31 FESS with manipulator-assisted endoscope guidance were performed. The used endoscope positions, the number of position changes and conditional interruptions were documented. In addition, a transsphenoidal approach to the pituitary gland was performed in a cadaver trial. RESULTS: Non-inferiority was shown for the use of the endoscope manipulator with reference to time and accuracy of manipulator-assisted endoscope guidance. There were 6.4 position changes for each side. Bimanual manipulation was possible in all cases. In the region of high-risk structures (lamina papyracea, frontal recess) we conceptual switched to manual endoscope guidance. CONCLUSION: The evaluated endoscope manipulator fulfills the minimum requirements to be integrated into the surgical workflow of endo- and transnasal surgery. The number of required endoscope position changes is small allowing bimanual instrumentation. Still a disadvantage is the need for interrupting the workflow to remote the endoscope manipulator with the joystick console. Further development potential would be a forced-feedback function and hands-free navigated-controlled guidance.

[The first clinical use of an Dynamic Registration Tool for Navigation in FESS]. / Der erste klinische Einsatz einer dynamischen (Nach-) Registrierung für die Navigation in der FESS.

BACKGROUND: The effective register accuracy in an situs issues a challenge to the employment of instrument navigation in the ENT Surgery. The idea of the initially determined process Dynamic Registration Supply (DRS) is to improve the register accuracy by the automatic, and interoperability of the register. MATERIALS AND METHODS: The aim was to determine clinical use of DRS. Opto-electrical system Navigation Panel Unit, vs. 4.0.0 with the functionality DRS was used. Experiments were carried out on 95 patients who had so called FESS. The data of a control group were available to researchers. The measuring log includes among other things following parameters: retooling time, cutting-suture time, frequency of use of the navigated pointer, frequency of additional registration. RESULTS: At least once during the procedure DRS has been activated in 85 of 95 interventions (89.5). The time required increased by 15% accumulated 189 s per intervention. The most frequently used additional registration was in the region of sphenoid sinus. The surgeons underlined that out of 95 surveys in 75 cases the DRS rendered the instrument navigation more precise, while 1% of 93 cases considered this function as unwanted. CONCLUSION: The first clinical study for use of an automatic algorithm for recognition and reduction of faulty registration of a CT, navigation was successful. The findings suggest that by using automatic intraoperative registration DRS consisting inaccuracy can be reduced. In practice this means an efficient quality improvement of the Navigation.

[Influence of an auto-motorised optical navigation camera to the surgical workflow in ENT surgery]. / Die Auswirkungen einer robotergeführten Navigationskamera in der HNO-Chirurgie.

BACKGROUND: With the application of optical navigation systems an interruption of the line of sight (LOS) between navigation camera and the patient/instrument can occur. The goal of this work is the clinical evaluation of a newly developed system for automatic adjusting of an optical navigation camera (Navigation Camera Assistant, NCA). NCA is a miniature robot, which is able to position the navigation camera autonomously in 2 levels. MATERIAL AND METHODS: The influence of the NCA was examined on 128 patients: 55 procedures at the paranasal sinuses and 9 procedures at the temporal bone with the NCA were evaluated and compared with available workflow data of adequate surgeries without NCA. An optical navigation system of the 3 (rd) generation was used. The following parameters were recorded: Preparation time of the system, time of using the system, LOS-interruptions. RESULTS: The LOS-interruption decreased in the group of FESS with application of the NCA by 92%, in the group tympanic cavity by 85%. The number of corrective motions of the navigation camera was increased with application of the NCA in the group FESS by 73%, in the group tympanic cavity by 89%. The usage time of navigation increased with the application of the NCA in the group of FESS by 36%, in the group tympanic cavity by 16%. CONCLUSIONS: With a motorized navigation camera can be the interruption rate of LOS significantly improved at frontal and lateral skull base. The technical expenditure for installation of the NCA robot is little even during, for this reason there is the potential that this module can be established for the clinical practice.

Design and fabrication of three-dimensional scaffolds for tissue engineering of human heart valves.

We developed a new fabrication technique for 3-dimensional scaffolds for tissue engineering of human heart valve tissue. A human aortic homograft was scanned with an X-ray computer tomograph. The data derived from the X-ray computed tomogram were processed by a computer-aided design program to reconstruct a human heart valve 3-dimensionally. Based on this stereolithographic model, a silicone valve model resembling a human aortic valve was generated. By taking advantage of the thermoplastic properties of polyglycolic acid as scaffold material, we molded a 3-dimensional scaffold for tissue engineering of human heart valves. The valve scaffold showed a deviation of only +/-3-4% in height, length and inner diameter compared with the homograft. The newly developed technique allows fabricating custom-made, patient-specific polymeric cardiovascular scaffolds for tissue engineering without requiring any suture materials.

Automation in surgery: a systematic approach.

This chapter proposes a classification of surgical assistance systems with respect to their type and level of automation. This classification is based on previous work in the field of human factors and takes two aspects into consideration, the type of information-processing function of the surgeon that is supported by the system, as well as the type of function allocation between surgeon and systems. With respect to the former, three basic functions are distinguished, referred to as information acquisition and analysis, decision making and planning, and execution of surgical action. With respect to the type of function allocation, the status of being either "passive" or "active" comes into consideration for both objects of reference (i.e. the surgeon and the machine), depending on whether a given function is mainly performed by the surgeon, by the system, or collaboratively by both. Hence, a classification results for intraoperative assistance systems in six categories, each of these representing a different degree of automation. The classification scheme is explained and illustrated on the basis of examples of surgical assistance systems from various fields.

Intraoperative computed tomography with the mobile CT Tomoscan M during surgical treatment of orbital fractures.

Up to now it has only been possible to monitor the alignment of orbital floor fractures postoperatively with a computed tomography (CT) examination with coronal sectioning. If this showed an incorrect positioning, renewed surgery and anaesthetics were often required. The purpose of this study was the implementation and definition of the spectrum of indications for intraoperative CT examinations while keeping patient radiation exposure to a minimum. Thirty-two orbital fracture cases were examined pre- and intraoperatively using the mobile computer tomograph Tomoscan M in coronal sectioning. In this patient collective, 12 cases showed an isolated orbital floor fracture and twenty cases an orbital floor fracture associated with a zygomatic fracture. The technical prerequisite for these examinations was the construction of a suitable radiolucent operating table which permitted coronal sections to be made with the CT-Gantry tilted. The authors aimed to reduce radiation exposure by optimizing the technical setting parameters and closely defining the scan region for the operator. In three of 32 cases there were no surgical indications following clinical and preoperative CT examination. In three of the 20 cases with associated zygomatic fracture a closed reduction with a reduction hook was carried out, and no revision was necessary after the intraoperative CT examination. In 26 cases an open reduction was carried out. Of these open reduced fractures, four had to be revised after intraoperative CT monitoring; one of the isolated orbital floor fractures and three of those associated with a zygomatic fracture. Intraoperative CT monitoring of orbital floor fractures is considered a useful surgical aid. Its advantages are immediate monitoring of the surgical reduction, the presence of the surgeon during scanning enabling him to determine directly the relevant sections to scan, and the resulting radiation exposure.

Evaluation of accuracy of insertion of dental implants and prosthetic treatment by computer-aided navigation in minipigs.

The survival of loaded implants is critically dependent on their biomechanical stability. We have used a computer-guided navigation technique to evaluate the accuracy of computer-assisted insertion for immediately-loaded implants in minipigs. On the basis of computed tomographical data, the Robodent system was used for preoperative planning and guidance of inserting the implant. An optical tracking system allowed positioning of the implant and immediate prosthetic rehabilitation by inserting it in a plaster model and during the operation. Postoperative computed tomograms (CT) showed that the implants were placed precisely in the preoperatively planned position. The accuracy achieved corresponded well with the spatial resolution of the CT used. Immediate placement of the prefabricated crowns resulted in favourable occlusal positioning. Histological cross-sections showed that the implants were biomechanically stable. The accuracy of insertion of oral implants illustrated here suggests that insertion and prosthetic modelling of implants may benefit from computer-assisted navigation.

Automatic patient registration in computer assisted maxillofacial surgery.

In this paper, a new approach for patient registration in computer assisted maxillofacial surgery is presented. The method uses a unique structure of markers embedded in a reference frame for the automatic detection of the coordinate system of the medical imaging data during the surgical intervention. With the new method, the inaccurate and time consuming process of manually identifying markers in the data volume and manually teaching them to a navigation system can be replaced. The method and algorithms for the automatic marker detection are described in this paper. Experiments with 45 data sets of patients proove the robustness, usability and safety of the new method. The method has been integrated into the navigation system RoboDent for dental implant surgery.

First application of behavoir recognition through the recording of ADL by radio modules in a home.

In this contribution the behavior of an elderly couple, recorded by a radio module system in their own home is analyzed. There is an increasing interest in giving elderly people the possibility to live at their own homes as long as possible. Since diseases like dementia are diagnosed through the change of behavior, especially the activities of daily living (ADL), there is a growing need of an objective instrument for measuring behavioral changes. Therefore the Eventlogger was developed and installed for 32 days in a home of an elderly couple. Throughout this paper the outcome of the data collection as well as first steps for analyzing it will be discussed. Furthermore we were able to observe different routines of the diseased and the healthy person. The diseased proband follows a very strict routine whereas the healthy proband routines are dependent on different factors.

Evaluation of a radio based ADL interaction recognition system in a day hospital for old age psychiatry with healthy probands.

In this contribution the evaluation of a system called "Eventlogger" is presented, which is installed in a day hospital for old age psychiatry. The Eventlogger is a radio based module with an adjustable communication range, able to recognize interaction of the user with objects or with other people. It is intended to function as a monitoring tool for the users' activities. Due to the demographic change monitoring systems for elderly people become more important. In this paper the "simple activities of daily living" (sADL) is introduced as well as the evaluation for the recognition of sADL in a day hospital for old age psychiatry with healthy probands is presented. Together with the first approaches of post processing for better results it is shown that the system is now ready to be used with patients of the day hospital for old age psychiatry.

Concept and modular telemedicine platform for measuring of vital signs, ADL and behavioral patterns of elderly in home settings.

In this contribution a new centralized platform for telemedicine is presented. It combines functions for measuring of vital signs, ADL and behavioral patterns and is especially designed for home care scenarios and the use by elderly people who are not familiar with the use of a PC. Unlike many other approaches we did not use a modified standard PC but developed a new dedicated hardware platform. It comes with various interfaces to communicate with different medical home care systems. We implemented a modular software architecture, which allows managing multiple user accounts with different personal settings. Every account can be adapted individually to the user. Every medical device that can be connected to the platform has its own software module, in which data is analyzed, displayed, stored to an internal database or transmitted to a server. Though the user is not bothered with technical issues such as setting up a connection to the internet, he keeps control on his data because he decides if and when data is transferred to a web server. The device was developed in an iterative process and evaluated in focus groups by n = 31 subjects (average age: 67 years) under the supervision of a psychogerontologist. All findings obtained from those sessions were directly incorporated in the presented work.

MiMed liver: a planning system for liver surgery.

In clinical routine of liver surgery there are a multitude of risks such as vessel injuries, blood loss, incomplete tumor resection, etc. In order to avoid these risks the surgeons perform a planning of a surgical intervention. A good graphical representation of the liver and its inner structures is of great importance for a good planning. In this work we introduce a new planning system for liver surgery, which is meant for computer tomography (CT) data analysis and graphical representation. The system is based on automatic and semiautomatic segmentation techniques as well as on a simple and intuitive user interface and was developed with the intention to help surgeons by planning an operation and increasing the efficiency in open liver surgery.

Comparison of manual steering and steering via joystick of a flexible rhino endoscope.

Flexible endoscopes are used in ENT surgery for examination tasks in cases wherever rigid endoscopes are unsuitable to reach certain positions in the nasal cavity. Until today they are steered by hand and no robotized system has been put into clinical practice. One qualification a robot manipulator system has to fulfill to be accepted is not to create new disadvantages compared to the conventional method in surgery. An important factor is the time needed to steer the new system compared to the time needed to steer the conventional system. In this article a robot manipulator system and an experiment are presented to compare the particular times test persons need to perform a certain task. This approach offers the possibility to benchmark the developed robot manipulator system and future systems for flexible rhino endoscopes.

Evaluation of a navigated and power controlled milling system "navigated control spine" for spinal surgery.

PURPOSE: The aim of this work was the evaluation of a navigated and power controlled milling system for spine surgery (navigated control spine). The navigation is based on a set of intraoperatively taken fluoroscopic images from different angles. A manually planned workspace limits the power of the mill and assures a higher automatisation degree than any other established navigation system for spine surgery. METHODS: Both a technical study in workspace planning from fluoroscopic images and a milling study on a spine phantom were performed with participants with different level of knowledge of spinal surgery. RESULTS: In the region of interest the workspace planning could be performed with a maximum excess of 1.40 mm for surgeons. In the study performing the milling of a standardised workspace the remnant bone after milling had a mean difference from the planned workspace margin of 1.96-2.12 mm in the region of most interest. Accurate handling of the mill still required a certain level of medical knowledge and experience. In both studies the time needed for application of the system proved acceptable for clinical purposes. DISCUSSION: This concept of navigated and power controlled spinal surgery has proven feasible in an experimental study. This navigation system seems therefore promising for clinical application.

Navigation of bone alignment osteotomies of the tibia.

This article describes a new bone segment navigation device for application in orthopaedic surgery. It allows for exact and CT-free alignment of bone segments according to a preset plan. The system guides the user through the initialisation process with only minor interaction. Once the bone segments are registered, an intuitive graphical model visualizes current spatial position relative to a desired (initial or planned) position. Advantages of the system are the usability without CT data and a very simple user interface. We describe the system, its components and the method of operation. Furthermore, an initial experiment to measure the overall repositioning accuracy during an experimental intervention is described, which was performed to access biomechanical information for the clinical analysis of osseo-integration processes is presented.

Tissue engineering of vascular conduits: fabrication of custom-made scaffolds using rapid prototyping techniques.

BACKGROUND: The technique of stereolithography, which automatically fabricates models from X-ray computed tomography or magnetic resonance imaging (MRI) data linked to computer-aided design programs, has been applied to the fabrication of scaffolds for tissue engineering. We previously reported on the application of stereolithography in scaffold fabrication of a trileaflet heart valve. In our current experiment we demonstrate a new technique for the fabrication of custom-made conduits for the potential replacement of a coarcted aortic segment. METHODS AND RESULTS: In this experiment the image data derived from a 12-year-old male patient with aortic coarctation scanned by MRI were processed by a computer-aided design program to reconstruct the aortic arch with isthmus stenosis three dimensionally. By defining the stenotic section and the adjacent normal vessel a custom-made nonstenotic descending aorta was reconstructed to replace the stenosed part. The rapid prototyping technique was used to establish stereolithographic models for fabricating biocompatible and biodegradable vascular scaffolds with the anatomic structure of the recalculated human descending aorta through a thermal processing technique. CONCLUSION: Our results suggest that the re-creation and reproduction of complex vascular structures by computer-aided design techniques may be useful to fabricate custom-made polymeric scaffolds for the tissue engineering of living vascular prostheses.