Differences in the Exposure of the Lumbar Nerve Root Between Experts and Novices: Results From a Realistic Simulation Pilot Study With Force Sensors.

STUDY DESIGN: Nonrandomized prospective trial. OBJECTIVE: Several studies could demonstrate "learning curves" in almost every single surgical procedure for unexperienced surgeons. This is in sharp contrast to the rising quality requirements in public health care to provide surgical training at patients "expense." The aim of this study was to visualize, measure, and set a baseline of the pressure load on the spinal nerve root during a simulated microdiscectomy on a standardized and validated model (RealSpine) under the influence of the level of surgical experience and individual skills. METHODS: Five highly experienced spine surgeons and 5 trainees without considerable surgical experience were selected to perform a standardized microsurgical discectomy on a validated RealSpine simulator. Force-torque sensors were integrated in this simulator to measure the load on the nerve root. The forces were recorded every 125 ms. RESULTS: We could identify cumulative for the total intervention as well as for defined single surgical steps of this procedure and as well in between the single subjects a significant higher tension and contusion forces on the nerve for the trainee group (Δp contusion 83-765 Ncs and Δp tension 159-1131 Ncs for the trainees. Δp contusion 16-171 Ncs and Δp tension 27-146 Ncs for the experts). CONCLUSION: We could measure a difference between unexperienced and experienced surgeons regarding the manipulations of the nerve root during a standardized simulated microdiscectomy. This possibility could be the starting point for a new and innovative surgical education to improve outcome without negative side effects of "learning curves."

Approaches towards training in human risk management of surgical technology.

A safe application of modern surgical technology and computer-assisted surgery devices is based on an operation by adequately trained surgeons who are familiar with the benefits and limitations of the devices. We analyzed the in-depth interviews with seven Spanish and 10 German surgeons. Together with other studies, this analysis highlights the need for specific training in technological competence for surgeons. One way to train technological competence is to help surgeons understanding the basic principles of medical devices as well as explaining the basic concepts of risk analysis and risk management. Based on this premise, a stage model for risk assessment was developed and adapted for the training of surgeons. This was developed further into a train the trainer (TTT) concept, which was then evaluated for two example cases. During TTT-training, the trainers (expert surgeons) performed a risk analysis for several medical devices. Afterwards, the trainers organized a surgical workshop for surgical trainees (resident surgeons), in which high-fidelity simulators and the original medical devices were used. The results showed that the surgeons performed the risk analysis correctly with the stage model and afterwards were able to successfully apply the results in the workshop context.

An anthropomorphic sonography phantom for the evaluation of mechatronic devices for heart surgery.

Surgical assistance systems are used to make surgical procedures more precise. The integration of automated intra-operative imaging in surgical interventions can be seen as an important step to further improve patient safety. An automatic soft tissue manipulation system with mechatronic assistance using endoscopic Doppler guidance was developed for minimally invasive coronary artery bypass surgery. To facilitate the complicated development process of the mechatronic system, we manufactured and validated an anthropomorphic phantom. A three-compartment model including soft tissue and a vessel system were manufactured for the phantom. Blood flow simulation was implemented using a pump and blood mimicking fluid in a closed circuit. Eighteen physicians evaluated the anatomical and physiological validity of the phantom in a study. The average rating of the anatomy, as well as the physiology, was good, although particular aspects of the phantom have shown a need for improvement. The validation study provided valuable information on limits and problems concerning the phantom and its applicability for the evaluation of the development steps of the mechatronic system. We showed how to develop and validate a phantom for the evaluation of a surgical assistance system with intraoperative imaging. The described concepts can be applied to similar developmental procedures and help generate a goal-driven and efficient development.

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.

Ontology for assessment studies of human-computer-interaction in surgery.

OBJECTIVE: New technologies improve modern medicine, but may result in unwanted consequences. Some occur due to inadequate human-computer-interactions (HCI). To assess these consequences, an investigation model was developed to facilitate the planning, implementation and documentation of studies for HCI in surgery. METHODS AND MATERIAL: The investigation model was formalized in Unified Modeling Language and implemented as an ontology. Four different top-level ontologies were compared: Object-Centered High-level Reference, Basic Formal Ontology, General Formal Ontology (GFO) and Descriptive Ontology for Linguistic and Cognitive Engineering, according to the three major requirements of the investigation model: the domain-specific view, the experimental scenario and the representation of fundamental relations. Furthermore, this article emphasizes the distinction of "information model" and "model of meaning" and shows the advantages of implementing the model in an ontology rather than in a database. RESULTS: The results of the comparison show that GFO fits the defined requirements adequately: the domain-specific view and the fundamental relations can be implemented directly, only the representation of the experimental scenario requires minor extensions. The other candidates require wide-ranging extensions, concerning at least one of the major implementation requirements. Therefore, the GFO was selected to realize an appropriate implementation of the developed investigation model. The ensuing development considered the concrete implementation of further model aspects and entities: sub-domains, space and time, processes, properties, relations and functions. CONCLUSIONS: The investigation model and its ontological implementation provide a modular guideline for study planning, implementation and documentation within the area of HCI research in surgery. This guideline helps to navigate through the whole study process in the form of a kind of standard or good clinical practice, based on the involved foundational frameworks. Furthermore, it allows to acquire the structured description of the applied assessment methods within a certain surgical domain and to consider this information for own study design or to perform a comparison of different studies. The investigation model and the corresponding ontology can be used further to create new knowledge bases of HCI assessment in surgery.

Development and validation of an artificial wetlab training system for the lumbar discectomy.

PURPOSE: An initial research indicated that realistic haptic simulators with an adapted training concept are needed to enhance the training for spinal surgery. METHODS: A cognitive task analysis (CTA) was performed to define a realistic and helpful scenario-based simulation. Based on the results a simulator for lumbar discectomy was developed. Additionally, a realistic training operating room was built for a pilot. The results were validated. RESULTS: The CTA showed a need for realistic scenario-based training in spine surgery. The developed simulator consists of synthetic bone structures, synthetic soft tissue and an advanced bleeding system. Due to the close interdisciplinary cooperation of surgeons between engineers and psychologists, the iterative multicentre validation showed that the simulator is visually and haptically realistic. The simulator offers integrated sensors for the evaluation of the traction being used and the compression during surgery. The participating surgeons in the pilot workshop rated the simulator and the training concept as very useful for the improvement of their surgical skills. CONCLUSIONS: In the context of the present work a precise definition for the simulator and training concept was developed. The additional implementation of sensors allows the objective evaluation of the surgical training by the trainer. Compared to other training simulators and concepts, the high degree of objectivity strengthens the acceptance of the feedback. The measured data of the nerve root tension and the compression of the dura can be used for intraoperative control and a detailed postoperative evaluation.

Evaluation of a training model to teach veterinary students a technique for injecting the jugular vein in horses.

In this study, a newly-developed model for training veterinary students to inject the jugular vein in horses was evaluated as an additional tool to supplement the current method of teaching. The model was first validated by 19 experienced equine veterinarians, who judged the model to be a realistic and valuable tool for learning the technique. Subsequently, it was assessed using 24 students who were divided randomly into two groups. The injection technique was taught conventionally in a classroom lecture and a live demonstration to both groups, but only group 1 received additional training on the new model. All participants filled out self-assessment questionnaires before and after group 1 received training on the model. Finally, the proficiency of both groups was assessed using an objective structured clinical evaluation (OSCE) on live horses. Students from group 1 showed significantly improved confidence after their additional training on the model and also showed greater confidence when compared to group 2 students. In the OSCE, group 1 had a significantly better score compared to group 2: the median (with inter-quartile range) was 15 (0.7) vs. 11.5 (2.8) points out of 15, respectively. The training model proved to be a useful tool to teach veterinary students how to perform jugular vein injections in horses in a controlled environment, without time limitations or animal welfare concerns. The newly developed training model offers an inexpensive, efficient, animal-sparing way to teach this clinical skill to veterinary students.

Patient safety related to the use of medical devices: a review and investigation of the current status in the medical device industry.

To reduce the risk of application error, the federal legislator has demanded a development process which is oriented towards usability (DIN EN 62366). Therefore, the research question concerns the application of this standard by medical device manufacturers. Questionnaires were filled out by five trained interviewers in fully standardized face-to-face interviews at MEDICA Düsseldorf 2010. The results are based on 65 interviews. Almost all companies evaluated usability as relevant for product development; however, the understanding of usability through companies can still be improved as well as increasing the amount of trained usability experts in the process.

Laparoscopic versus robot-assisted Nissen fundoplication in an infant pig model.

PURPOSE: Surgical robots are designed to facilitate dissection and suturing, although objective data on their superiority are lacking. This study compares conventional laparoscopic Nissen fundoplication (CLNF) to robot-assisted Nissen fundoplication (RANF) using computer-based workflow analysis in an infant pig model. METHODS: CLNF and RANF were performed in 12 pigs. Surgical workflow was segmented into phases. Time required to perform specific actions was compared by t test. The quality of knot-tying was evaluated by a skill scoring system. Cardia yield pressure (CYP) was determined to test the efficacy of the fundoplications, and the incidence of complications was compared. RESULTS: There was no difference in average times to complete the various phases, despite faster robotic knot-tying (p = 0.001). Suturing quality was superior in CLNF (p = 0.02). CYP increased similarly in both groups. Workflow-interrupting hemorrhage and pneumothorax occurred more frequently during CLNF (p = 0.040 and 0.044, respectively), while more sutures broke during RANF (p = 0.001). CONCLUSION: The robot provides no clear temporal advantage compared to conventional laparoscopy for fundoplication, although suturing was faster in RANF. Fewer complications were noted using the robot. RANF and CLNF were equally efficient anti-reflux procedures. For robotic surgery to manifest its full potential, more complex operations may have to be evaluated.

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.

Workflow analysis of laparoscopic Nissen fundoplication in infant pigs- a model for surgical feedback and training.

BACKGROUND: Many fields use workflow analysis to assess and improve performance of complex tasks. In pediatric endosurgery, workflow analysis may help optimize operative planning and motor skills by breaking down the procedure into particular phases, evaluating these steps individually, and supplying feedback to the surgeon. OBJECTIVE: To develop a module of computer-based surgical workflow analysis for laparoscopic Nissen fundoplication(LNF) and to evaluate its applicability in an infant pig model. METHODS: LNF was performed in 12 pigs (weight, 7-10 kg) by a single surgeon. Based on synchronized intra and extracorporal movie recordings, the surgical workflow was segmented into temporal operative phases(preparation, dissection, reconstruction and conclusion). During each stage, all actions were recorded in a virtual timeline using a customized workflow editor. Specific tasks, such as knot-tying, were evaluated in detail.Time necessary to perform these actions was compared throughout the study. RESULTS: While time required for the preparation decreased by more than 70% from 4577 to 1379 seconds,and the dissection phase decreased from 2359 to 399 seconds (pig 1 and 12, respectively), the other two phases remained relatively stable. Mean time to perform the entire suture and a 5-throw knot remained constant as well. CONCLUSION: Our workflow analysis model allows the quantitative evaluation of dynamic actions related to LNF.This data can be used to define average benchmark criteria for the procedures that comprise this operation. It thereby permits task-oriented refinement of surgical technique as well as monitoring the efficacy of training.Although preoperative preparation time decreased substantially, and dissection became faster, time required for the reconstruction and conclusion phases remained relatively constant for a surgeon with moderate experience.Likewise, knot-tying did not accelerate in this setting.S-117

A process and criteria for the evaluation of software frameworks in the domain of computer assisted surgery.

Software application frameworks provide a modular and reusable context for the development of custom applications, e.g. in the domain of medical image processing and computer assisted surgery (CAS). The utilization of an appropriate software framework can strongly reduce time and costs for software design, implementation, and validation. However, the decision to apply a particular framework poses many risks that can have an impact on the success of the overall software project. There is a need for a software framework evaluation methodology that guides the selection process in an objective, impartial, and repeatable manner. This work defines an evaluation process for the selection of software application frameworks out of a group of candidates that fit best to defined requirements necessary for the development of CAS applications.

[ElePhant: an anatomic-electronic simulation system for the evaluation of computer assisted interventions and surgical education]. / ElePhant: ein anatomisch-elektronisches Simulationssystem für die Evaluation computerassistierter Eingriffe und die chirurgische Ausbildung.

BACKGROUND: Suitable simulation systems providing realistic conditions are required for preclinical evaluation of computer assisted interventions and surgical training. Techniques are necessary for an objective detection of injuries to the structures at risk. The aim of this study was the technical realization of a simulation system for the ENT intervention, mastoidectomy. MATERIALS AND METHODS: The basis of the simulation system was a CT scan of a cadaver skull. Using 3D printing, an anatomical phantom with realistic bone-like properties was created. Electronic detection systems were integrated into the structures at risk. A study with 16 ENT surgeons was conducted to prove the system's suitability for surgical training. RESULTS: The creation of simulation systems for the objective evaluation of surgical intervention qualities is feasible. A modular structure enables economic and simple replacement of the simulation area. The modules are cost effective and reproducible with high accuracy. The present study shows that the simulation system can be applied in surgical education and evaluation as an alternative to cadavers. CONCLUSION: Objective evaluation of injured structures at risk can be realized in real time. The simulation system permits preclinical evaluation studies of computer assisted instruments and surgical education. Reproducibility of the results makes multi-center studies possible.

Surgical cartographic navigation system for endoscopic bypass grafting.

Endoscopic bypass grafting with the da Vinci system is still challenging and needs high level of experience and skill of the surgeon. Therefore, it is necessary to support the surgeon with enhanced vision and augmented reality. The augmentation of the patient model into the view of the endoscope is a direct approach to enhance support. The results of a preclinical study are shown in this paper. The method applied is suitable for endoscopic bypass grafting and in general applicable to minimal invasive surgery. The system was designed as an open architecture to facilitate easy transfer of the methodology into other surgical domain applications.

The navigation-controlled drill in temporal bone surgery: a feasibility study.

BACKGROUND: This study examines the feasibility of a navigation-controlled (NC) drill for surgery on the petrosal bone in an experimental environment. According to the principle of NC, the drill is to be switched off automatically once the borders of the workspace are exceeded during a mastoidectomy. MATERIALS AND METHODS: The registration is based on an optical navigation system with navigation software (MiMed). As surgery engine, the Unidrive-system (Karl Storz GmbH & CO. Kg, Tuttlingen, Germany) was integrated. The definition of the workspace was performed manually in axial computed tomography (CT) slices of the petrosal bone phantom. The mastoidectomy on the model was accomplished in three runs with 10 trial surgeons altogether (5 experienced [exp.] in otologic (ear) surgery, 5 inexperienced [nonexp.]). During each run, the following were logged: the total length of time for the procedure as well as the number and extent of injuries to the risk structures (facial nerve, horizontal semicircular canal, sigmoid sinus). The resultant petrosal bone cavities were measured on the CT. RESULTS: The time for the segmentation of the workspace for the mastoidectomy amounted to 17 minutes. The mean value of the drilling (e.g., milling) performance ranges from 6.61 mm3/s (group 1 [nonexp. + NC]), 9.62 mm3/s (group 2 [exp. w/o NC]), to 10.08 mm3/s (group 3 [exp. + NC]). The relative deviation to the segmented volume amounts to +7.4% (794.3 mm3) for group 1, -39.9% for group 2, and -34% (3,647.0 mm3) for group 3. In the groups with NC guidance of the drill, no damage to a risk structure could be logged. In the group of exp. ear surgeons without NC assistance, one injury to the facial nerve in the petrosal bone phantom occurred. DISCUSSION: The results that follow prove the fundamental feasibility of an NC drill for surgery of the petrosal bone using the example of the simple mastoidectomy in the laboratory test. When using NC, tissue resection is faster, more precise, and has fewer related complications than the same procedure without. The results offer a very promising basis for the introduction of a newly conceived system to the procedure of NC surgery on the petrosal bone. The device configuration used here was originally conceived for NC guidance of a shaver in functional endoscopic sinus surgery. Individual errors will have to be mitigated through the new version of the control unit presently in development.

Evaluation of a navigation system for ENT with surgical efficiency criteria.

The aim of this study is the evaluation of a navigation system (NaviBase) for ENT surgery. For this purpose, a new methodology for the evaluation of surgical and ergonomic system properties has been developed. The practicability of the evaluation instruments will be examined using the example of the overall assessment of the system in comparison with the current surgical standard and with other systems using clinical efficiency criteria. The evaluation is based on 102 ENT surgical applications; of these, 89 were functional endoscopic sinus surgeries (FESS). The evaluation of surgical and ergonomic performance factors was performed by seven ENT surgeons. To evaluate surgical system properties, the Level of Quality (LOQ) in 89 cases of the FESS was determined. It compares the existing information of the surgeon with that of the navigation system on a scale of 0 to 100 and with a mean value of 50 and places it in a relationship to the clinical impact. The intraoperative change of the planned surgical strategy (Change of Surgical Strategy) was documented. The ergonomic factors of the system with the categories of Overall Confidence (Trust), awareness of the situation (Situation Awareness), influence on the operating team, requirements for specific skills (Skill Set Requirement), and cognitive load (Workload Shift) were recorded for all surgical procedures as Level of Reliance (LOR). In the evaluation of the surgical system properties, an average evaluation of the quality of the information, as an LOQ of 63.59, resulted. Every second application of the navigation system (47.9%), on average, led to a change in the surgical strategy. An extension/enhancement of the indication of the endonasal approach through the use of the navigation system was shown in 7 of 102 (6.8%) cases. The completion of the resection in the FESS was rated by 74% of group I and 11% of group II as better in comparison with the standard approach. Total confidence shows a positive evaluation of 3.35 in the LOR. To supplement the evaluation of the navigation system, the technical parameters were included. The maximum deviation, Amax, of the displayed position of the reference value amounted to 1.93 mm. The average deviation was at 1.29 mm with an SD above all values, sd, of 0.29. The subsequent economic evaluation resulted in an effective average extra expenditure of time of 1.35 minutes per case. The overall evaluation of the system imparts application-relevant information beyond the technical details and permits comparability between different assistance systems.

Surgical PACS for the digital operating room. Systems engineering and specification of user requirements.

For better integration of surgical assist systems into the operating room, a common communication and processing plattform that is based on the users needs is needed. The development of such a system, a Surgical Picture Aquisition and Communication System (S-PACS), according the systems engineering cycle is oulined in this paper. The first two steps (concept and specification) for the engineering of the S-PACS are discussed.A method for the systematic integration of the users needs', the Quality Function Deployment (QFD), is presented. The properties of QFD for the underlying problem and first results are discussed. Finally, this leads to a first definition of an S-PACS system.

Development and first patient trial of a surgical robot for complex trajectory milling.

OBJECTIVE: Today's surgical robots normally perform "simple" trajectories, e.g., assisting as tool-holding devices in neurosurgery, or milling linear paths for cavities in total hip replacement. From a clinical point of view, it is still a complex undertaking to implement robots in the operating room. Until now, robot systems have not been used in patient trials to mill "complex" trajectories, which involve many positional and orientation changes and are often necessary in cranio-maxillofacial (CMF) surgery. This paper presents the RobaCKa surgical robot system, which allows more precise execution of surgical interventions and milling of "complex" trajectories. MATERIALS AND METHODS: The main components of the RobaCKa system are a (former) CASPAR robot system, a POLARIS system, and a force-torque sensor. RESULTS: In the first patient trial (April 2003) the planned trajectory was executed with an error of 0.66 +/- 0.2 mm. CONCLUSIONS: The use of former industrial robots for surgical applications is possible but complex. The advantages are improved precision and quality and the possibility of documentation. The use of such systems is normally limited to research institutions or large clinics, because it is hardly possible to implement the necessary technical and logistic efforts in routine surgical work.