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.

Voice Handicap Index-18 as an Instrument for Assessing Subjective Voice Impairment Between Voice Pre- and Post-treatment.

The Voice Handicap Index (VHI) is today regarded as the gold standard for measuring the subjective impairment of a voice disorder. The aim of our study is to present how the VHI in our version with 18 questions (VHI-18) can be evaluated with other patient collectives (practice visitors or everyday patients). The previous publications have shown that most patient groups were stationary or clinical. A total of 100 adult patients (72 female, 28 male) in our medical practice KOPFZENTRUM were examined. The reliability of the VHI-18 results from a Cronbach's Alpha (0.92). The VHI-18 is suitable as a diagnostic instrument for medical practices or logopaedic practices.

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.

The application of surgical procedure manager (SPM): first experience with FESS.

In our hypothesis, the newly developed program SPM (surgical procedure manager) will ensure successful standardization and efficiency of the FESS (functional endoscopic sinus surgery) and therefore make a decisive contribution in terms of economization and improvement of intraoperative quality. Between 27th March 2015 and 8th October 2015, data from 259 FESS procedures were collected using the SPM. The study took place at the surgical desk, an operating room in the ACQUA clinic in Leipzig, Germany. 233 FESS (90%) of the total FESS (n = 259, 100%) were conducted entirely with SPM. 26 SPM terminations (10%) of 259 FESS remain, which are classified as actual SPM terminations-when the surgeon intentionally stops the SPM. The maximum time slot decreased clearly from 1 h 39 min (period A) to 1 h 10 min (period B). A time reduction can also be seen with the minimum duration of 13.5 min compared to 11 min. The variability of the time slot also decreases since the standard deviation is reduced by 4.5 min. On the basis of available recordings it can be postulated that the application of SPM is suitable for standardization for FESS. Standardization by means of SPM and minimal development can be recognized over a period of time. The SPM makes it possible to transfer the general advantages of mechanization on a concrete FESS and do not influence the medical processes nor even restrict the medical freedom. The users are still entirely free in the implementation of the respective procedure.

Web-tool to Support Medical Experts in Probabilistic Modelling Using Large Bayesian Networks With an Example of Hinosinusitis.

For many complex diseases, finding the best patient-specific treatment decision is difficult for physicians due to limited mental capacity. Clinical decision support systems based on Bayesian networks (BN) can provide a probabilistic graphical model integrating all necessary aspects relevant for decision making. Such models are often manually created by clinical experts. The modeling process consists of graphical modeling conducted by collecting of information entities, and probabilistic modeling achieved through defining the relations of information entities to their direct causes. Such expert-based probabilistic modelling with BNs is very time intensive and requires knowledge about the underlying modeling method. We introduce in this paper an intuitive web-based system for helping medical experts generate decision models based on BNs. Using the tool, no special knowledge about the underlying model or BN is necessary. We tested the tool with an example of modeling treatment decisions of Rhinosinusitis and studied its usability.

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).

Solving challenges in inter- and trans-disciplinary working teams: Lessons from the surgical technology field.

INTRODUCTION: Engineering a medical technology is a complex process, therefore it is important to include experts from different scientific fields. This is particularly true for the development of surgical technology, where the relevant scientific fields are surgery (medicine) and engineering (electrical engineering, mechanical engineering, computer science, etc.). Furthermore, the scientific field of human factors is important to ensure that a surgical technology is indeed functional, process-oriented, effective, efficient as well as user- and patient-oriented. Working in such trans- and inter-disciplinary teams can be challenging due to different working cultures. The intention of this paper is to propose an innovative cooperative working culture for the interdisciplinary field of computer-assisted surgery (CAS) based on more than ten years of research on the one hand and the interdisciplinary literature on working cultures and various organizational theories on the other hand. METHODOLOGY: In this paper, a retrospective analysis of more than ten years of research work in inter- and trans-disciplinary teams in the field of CAS will be performed. This analysis is based on the documented observations of the authors, the study reports, protocols, lab reports and published publications. To additionally evaluate the scientific experience in an interdisciplinary research team, a literature analysis regarding scientific literature on trans- and inter-disciplinarity was performed. Own research and literature analyses were compared. RESULTS: Both the literature and the scientific experience in an interdisciplinary research team show that consensus finding is not always easy. It is, however, important to start trans- and interdisciplinary projects with a shared mental model and common goals, which include communication and leadership issues within the project teams, i.e. clear and unambiguous information about the individual responsibilities and objectives to attain. This is made necessary due to differing leadership cultures within the cooperating disciplines. Another research outcome is the relevance of a cooperative learning culture throughout the complete duration of the project. Based on this cooperation, new ideas and projects were developed, i.e. a training concept for surgical trainers including technological competence for surgeons. DISCUSSION: An adapted innovative paradigm for a cooperating working culture in CAS is based on a shared mental model and common goals from the very beginning of a project. CONCLUSIONS: All actors in trans- and inter-disciplinary teams need to be interested in cooperation. This will lead to a common view on patients and technology models.

Less is sometimes more: a comparison of distance-control and navigated-control concepts of image-guided navigation support for surgeons.

Image-guided navigation (IGN) systems provide automation support of intra-operative information analysis and decision-making for surgeons. Previous research showed that navigated-control (NC) systems which represent high levels of decision-support and directly intervene in surgeons' workflow provide benefits with respect to patient safety and surgeons' physiological stress but also involve several cost effects (e.g. prolonged surgery duration, reduced secondary-task performance). It was hypothesised that less automated distance-control (DC) systems would provide a better solution in terms of human performance consequences. N = 18 surgeons performed a simulated mastoidectomy with NC, DC and without IGN assistance. Effects on surgical performance, physiological effort, workload and situation awareness (SA) were compared. As expected, DC technology had the same benefits as the NC system but also led to less unwanted side effects on surgery duration, subjective workload and SA. This suggests that IGN systems just providing information analysis support are overall more beneficial than higher automated decision-support. PRACTITIONER SUMMARY: This study investigates human performance consequences of different concepts of IGN support for surgeons. Less automated DC systems turned out to provide advantages for patient safety and surgeons' stress similar to higher automated NC systems with, at the same time, reduced negative consequences on surgery time and subjective workload.

Potential of the navigated controlled surgery at the lateral skull base with the navigated control unit (NCU 2.0).

Segmentation for navigated control was in the first generation very time consuming. In the present version (NCU 2.0) the risk structure is segmented (instead of the work space), this leads to an enormous decrease in preparation time. In additional, new safety functions were integrated. The segmentation feasibility was tested on patient data and proved to be successful. The automatic stop function was tested on petrous bone models and showed no damage to the facial nerve.

A new evaluation and training system for micro-telemanipulation at the middle ear.

In this article, a new surgical model for evaluating telemanipulators used in middle ear surgery is presented. The purpose of this work was to develop an evaluation and training system which imitates a typical surgical task of middle ear surgery and which can easily be repeated in order to get significant result. The abstract task can be performed manually or by means of a microsurgical telemanipulator and guaranties stable experimental conditions between different subjects at any time. As a task the stapedotomy was chosen, due to the high demands in positioning and in applying forces to the delicate structures in the middle ear. The manual and telemanipulated performance of 15 ENT surgeons and 17 medical students was compared using this evaluation and training system.

Distance measurement in middle ear surgery using a telemanipulator.

In this article, a new tool for the intraoperative measurement of distances within the middle ear by means of a micromanipulator is presented. The purpose of this work was to offer the surgeon a highly accurate tool for measuring the distances between two points in the 3D operational field. The tool can be useful in various operations; this article focuses, however, on measuring the distance between the stapes footplate and the long process of the incus of the middle ear. This distance is important for estimating the proper prosthesis length in stapedotomy for treating otosclerosis. We evaluated the system using a simplified mechanical model. Our results show that the system can measure distances with a maximum error of 0.04 mm.

A technique with manipulator-assisted endoscope guidance for functional endoscopic sinus surgery: proof of concept.

OBJECTIVE: The goal of this study was to examine the theoretical feasibility of a new manipulator system for endoscope guidance in functional endoscopic sinus surgery. STUDY DESIGN: The accuracy of endoscope positioning and time of endoscope movement with an endoscope manipulator system were determined with an artificial sinus model. SETTING: A laboratory trial was performed. The time for 60 repetitions of manual compared to manipulator-assisted endoscope movements directed at 3 different target positions was evaluated. In addition, the alignment of the position vector for each endoscope movement was examined. SUBJECTS AND METHODS: A zero-degree Hopkins II telescope with a camera was used to head for the target positions. First, the endoscope movements were done manually, and afterward the endoscope manipulator system was used for endoscope guidance. The alignment of the position vector of the endoscope was measured with a portable measuring arm. RESULTS: There was no statistical difference between the time for manual and manipulator-assisted endoscope movements for all target positions. The alignment of the position vector of the endoscope was statistically different at 2 target positions: anterior ethmoid left side and ostium of maxillary sinus left side. There was no statistical difference at all other positions. CONCLUSION: The endoscope manipulator system has the potential to be integrated into the operating workflow without extending the time for endoscope guidance. The surgeon will be able to use both hands for the manipulation of the instruments. Less frequent endoscope movements and instrument changes may be expected after technical modification.

Design and accuracy evaluation of a new navigated drill system for computer assisted ENT-surgery.

In this article a new navigated drill system for computer assisted ear, nose and throat (ENT) surgery is presented. The navigated drill and the microscope probe are part of a surgical navigation system for ENT-surgery. In particular, the accuracy of the new navigated drill is compared to an existing navigated drill experimentally under conditions close to the surgical workflow. For the technical accuracy experiment, the new navigated drill in combination with the new microscope probe and a particular navigated measurement board have been integrated, together with the current navigated drill, in a navigation system by a special navigation software with measuring function, based on a standard ENT navigation software. The developed navigated measurement board provided the implementation of reproducible experiments and the direct accuracy comparison of the two navigated instruments under the same conditions. Thereby, N = 15 accuracy experiments are performed with both navigated drill systems with three possible tracker positions. The distance between the planned and the touched points were calculated and compared. The average distances from the planned points to the touched points with the new navigated drill is in the left tracker position 1.10 mm, in the middle tracker position 1.14 mm and in the right tracker position 1.59 mm. In comparison to the existing drill, the new navigated drill, measured with each tracker position, is 0.62 mm more accurate.

Surgical assistance for instruments' power control based on navigation and neuromonitoring.

In order to prevent nerve injuries during ear-nose-throat (ENT) and skull base surgery, the method Navigated Control Functional is presented. Thereby, the power of active instruments is controlled based on position information, provided by a surgical navigation system, and nerve activity information, provided by a neurophysiologic monitoring system. Electrical stimulation is usually required for the extraction of distance information from neurophysiologic signals (e.g., Electromyography (EMG)). However, this article presents an experiment to investigate a possible relationship between EMG signals and the nerve-instrument distance without additional electrical stimulation. The EMG signals and position information were recorded intra-operatively during ear surgery. An off-line statistical analysis with Spearman's rank correlation coefficient was accomplished. The results show that there is occasionally some correlation at a statistically significant level of 5%. They highly depend on time range, the selected threshold value and time window. Moreover, all the observed correlations are positive against an expected negative correlation.

Automation in surgery: the impact of navigated-control assistance on performance, workload, situation awareness, and acquisition of surgical skills.

OBJECTIVE: Human performance consequences of a new technology of image-guided navigation (IGN) support for surgeons are investigated. BACKGROUND: Navigated control (NC) represents an advancement of IGN technology. In contrast to currently available pointer-based systems, it represents a higher degree of automation that supports processes not only of information analysis and integration but also of intraoperative decision making. METHOD: In the first experiment, 14 surgical novices performed a simulated mastoidectomy with and without NC support. Effects of provision of the system were analyzed with respect to different measures of surgical performance and outcome, workload, and situation awareness. In the second experiment, 21 advanced medical students were trained to perform a mastoidectomy by practicing it either with or without NC support. It was investigated to what extent the provision of the system during practice would affect the acquisition of surgical skills. RESULTS: The results reveal that NC support can reduce both the risk of intraoperative injuries and complications as well as the physiological effort of surgeons. "Cost effects" compared to a conventional (i.e., not supported) surgery emerged with respect to the time needed for the surgery, increased subjective workload, reduced spare capacity, and a reduced level of situation awareness. However, no significant effects on processes of skill acquisition were found. CONCLUSION: NC systems can contribute to improved patient safety. Most of the cost effects seem to be related not to the basic principle of NC but to its current technological implementation. APPLICATION: The results have consequences for the design and clinical use of automated navigation support.

Systematic user-based assessment of "Navigated Control Spine" / Systematische, nutzerzentrierte Evaluation von "Navigated Control Spine".

The aim of this study was the systematic preclinical assessment of a new mill for spinal surgery. This mill automatically switches off at predefined workspace margins. The system is called the "Navigated Control Spine". The workspace is planned intraoperatively with fluoroscopic images. Assessment was performed in a simulated surgical scenario with real surgical instruments and equipment, and the following criteria were measured: "milling accuracy" and "surgical workflow parameters". To simulate the patient, an anatomical spine model was created with a Rapid Prototyping machine. The models included electronic components that simulate injuries to the structures at risk. For the workflow parameters, the results show differences between experienced and inexperienced surgeons. The maximum accuracy for experienced surgeons was +0.31 mm and for inexperienced surgeons +0.57 mm. The dura, as one of the structures at risk, was never injured.

The influence of various registration procedures upon surgical accuracy during navigated controlled petrous bone surgery.

OBJECTIVE: The goal of this study was to investigate the dependence of surgical accuracy with a navigated controlled (NC) drill on selected registration procedures. STUDY DESIGN: The target registration error of the instrument and the maximum proximity to a typical high-risk structure (facial nerve) were determined within an artificial petrous bone. SETTING: The studies took place in two groups: group 1, navigation bow with six integrated markers and attachment at the upper jaw, and group 2, landmark registration with four titanium microscrews. Measurement of the target registration error took place at three targets (3 titanium screws) with 20 repeated registration procedures via evaluation of the deviation between a target and the indicated position in the navigation data. SUBJECTS AND METHODS: For measurement of the conversion accuracy of the planned cavity, 20 petrous bone models were milled by inexperienced test subjects. The evaluation of 20 cavities was conducted via a microscope by five jurors. RESULTS: Registration accuracy showed a maximum deviation between the actual position achieved and the computed position in the navigation system of 1.73 mm in group 1 and 0.93 mm in group 2. In group 1, the nerve in five of 20 cases was damaged, and a maximum penetration into the nerve of 1.5 mm (0.25 mm SD; milled beyond) was measured. In group 2, the facial nerve was not damaged at all, and a maximum deviation of 0.5 mm (0.63 mm SD; stopped before) was measured. CONCLUSION: The results for registration and conversion accuracy are significantly better for the landmark-based registration than with the registration of the patient model with registration bow on the upper jaw.

Assessment of technical needs for surgical equipment by surgical process models.

The presented approach introduces a method for estimating the potential benefit of a surgical assist system prior to its actual development or clinical use. The central research question is: What minimal requirements must a future system meet so that its use would be more advantageous than a conventional or already existent method or system, and how can these requirements be obtained from routine clinical data? Forty-three cases of lumbar discectomies were analyzed with regard to activities related to bone ablation in order to predict the temporal requirements for an alternative strategy of using a surgical assist system for bone ablation. The study recorded and analyzed surgical process models (SPM), which are progression models with detailed and exact-to-the-second representations of surgical work steps, as a sensible means for the detailed quantification of the temporal needs of the system. The presented methods can be used for a systematic analysis of such requirements. Implementation of these methods will prove very useful in the future from a medical, technical, and administrative point of view. Manufacturers can use this analytical procedure to derive parameters for their systems that indicate success criteria. Additionally, hospitals can decide, before making actual capital expenditure decisions, if the system of interest is superior to the conventional strategy and therefore worth the investment.

Image-guided navigation: the surgeon's perspective on performance consequences and human factors issues.

BACKGROUND: Image-guided navigation (IGN) represents a first step in the automation of surgical functions. The use of IGN can involve several human factors issues that must be taken into account when evaluating their impact on surgical performance and patient safety. METHODS: A nationwide survey was conducted among 213 surgeons from 112 German hospitals in order to assess the perceived performance consequences and human factors issues of IGN, including changes of situation awareness, performance and workload, as well as issues of overreliance, skill degradation and usability. RESULTS: Generally, surgeons report improved performance and patient safety related to the use of IGN. However, issues of increased time pressure and mental demands were reported by inexperienced users. Furthermore, overreliance on IGN represents a risk, albeit only in a minority of respondents. CONCLUSIONS: IGN is evaluated as a helpful tool for surgeons. However, special care should be taken to provide surgeons with sufficient time and training during familiarization with an IGN system.