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Visual performance and visual comfort are a combined effect of the illumination characteristics and the illuminated objects. Current surgical lighting systems have a fixed shape illumination pattern, whereas the wound and surroundings have a variable shape and characteristics. A lighting system that is able to adapt its shape and light distribution to the characteristics of the wound might improve visual performance. This paper describes the development of a new concept for lighting using bendable strips with LEDs. The basic idea of placing LEDs on a bendable surface is very simple and elegant. To achieve a functional system, the effects of the different design choices, such as shape of the strips, number of LEDs, number of strips, and LED power were investigated. The influence of these choices is evaluated by simulation using a computational model to identify the optimal parameters for the design. The final design is evaluated using the computational model and a physical prototype consisting of one luminaire segment. The system is able to produce light fields that can have fairly complex shapes at a good range of different sizes. Recommendations about aspects like spot size and strip number are given. The physical test model indicates that the calculated system functions close to how it would in a real-life situation. Given the results, it expected that a system, which is able to modify the light field in real time and that requires minimal control effort, could improve lighting in the operating room. [ABSTRACT FROM AUTHOR]

Box trainers equipped with sensors may help in acquiring objective information about a trainee's performance while performing training tasks with real instruments. The main aim of this study is to investigate the added value of force parameters with respect to commonly used motion and time parameters such as path length, motion volume, and task time. Two new dynamic bimanual positioning tasks were developed that not only requiring adequate motion control but also appropriate force control successful completion. Force and motion data for these tasks were studied for three groups of participants with different experience levels in laparoscopy (i.e., 11 novices, 19 intermediates, and 12 experts). In total, 10 of the 13 parameters showed a significant difference between groups. When the data from the significant motion, time, and force parameters are used for classification, it is possible to identify the skills level of the participants with 100% accuracy. Furthermore, the force parameters of many individuals in the intermediate group exceeded the maximum values in the novice and expert group. The relatively high forces used by the intermediates argue for the inclusion of training and assessment of force application during tissue handling in future laparoscopic skills training programs. [ABSTRACT FROM PUBLISHER]

Background: Objective assessment of psychomotor skills has become an important challenge in the training of minimally invasive surgical (MIS) techniques. Currently, no gold standard defining surgical competence exists for classifying residents according to their surgical skills. Supervised classification has been proposed as a means for objectively establishing competence thresholds in psychomotor skills evaluation. This report presents a study comparing three classification methods for establishing their validity in a set of tasks for basic skills' assessment. Methods: Linear discriminant analysis (LDA), support vector machines (SVM), and adaptive neuro-fuzzy inference systems (ANFIS) were used. A total of 42 participants, divided into an experienced group (4 expert surgeons and 14 residents with >10 laparoscopic surgeries performed) and a nonexperienced group (16 students and 8 residents with <10 laparoscopic surgeries performed), performed three box trainer tasks validated for assessment of MIS psychomotor skills. Instrument movements were captured using the TrEndo tracking system, and nine motion analysis parameters (MAPs) were analyzed. The performance of the classifiers was measured by leave-one-out cross-validation using the scores obtained by the participants. Results: The mean accuracy performances of the classifiers were 71 % (LDA), 78.2 % (SVM), and 71.7 % (ANFIS). No statistically significant differences in the performance were identified between the classifiers. Conclusions: The three proposed classifiers showed good performance in the discrimination of skills, especially when information from all MAPs and tasks combined were considered. A correlation between the surgeons' previous experience and their execution of the tasks could be ascertained from results. However, misclassifications across all the classifiers could imply the existence of other factors influencing psychomotor competence. [ABSTRACT FROM AUTHOR]

The success of total hip arthroplasty depends on the experience of the surgeon, and one of the ways the surgeon currently determines the final implant insertion depth is to listen to the change in audible pitch of the hammering sound. We investigated the use of vibration emissions as a novel method for insertion quality assessment. A non-invasive contact microphone-based measurement system for insertion depth estimation, fixation and fracture detection was developed using a simplified in vitro bone/implant (n = 5). A total of 2583 audio recordings were analyzed in vitro to obtain energy spectral density functions. Out of the four main resonant peaks under in vitro conditions, broach insertion depth statistically correlates to increasing 3rd and 4th peak frequencies. Degree of fixation was also observed as higher goodness of fit (0.26–0.78 vs. 0.12–0.51 between two broach sizes, the latter undersized). Finally, however, the moment of fracture could not be predicted. A cadaveric in situ pilot study suggests comparable resonant frequencies in the same order of magnitudes with the bone model. Further understanding of the signal patterns are needed for an early warning system diagnostic system for imminent fractures, bone damage, improving accuracy and quality of future procedures. [ABSTRACT FROM AUTHOR]

When equipped with motion and force sensors, box-trainers can be good alternatives for relatively expensive Virtual Reality (VR) trainers. As in VR trainers, the sensors in a box trainer could provide the trainee with objective information about his performance. Recently, multiple tracking systems were developed for classification of participants based on motion and time parameters. The aim of this study is the development of force parameters that reflect the trainee's performance in a suture task. Our second goal is to investigate if the level of the participant's skills can be classified as experts or novice level. In the experiment, experts (n = 11) and novices (n = 21) performed a two-handed needle driving and knot tying task on artificial tissue inside a box trainer. The tissue was mounted on the Force platform that was used to measure the force, which the subject applied on the tissue in three directions. We evaluated the potential of 16 different performance parameters, related to the magnitude, direction, and variability of applied forces, to distinguish between different levels of surgical expertise. Nine of the parameters showed significant differences between experts and novices. Principal Component Analysis was used to convert these nine partly correlating parameters, such as peak force, mean force, and main direction of force, into two uncorrelated variables. By performing a Leave-One-Out-Cross Validation with Linear Discriminant Analysis on each participants' score on these two variables, it was possible to correctly classify 84 percent of all participants as an expert or novice. We conclude that force measurements in a box trainer can be used to classify the level of performance of trainees and can contribute to objective assessment of suture skills. [ABSTRACT FROM PUBLISHER]

Surgical overhead luminaires and head-mounted luminaires are important tools for surgeons. The optical design of these luminaires focuses on providing shadow free light. Shadows, however, are reported as important cues for depth perception in mono- and stereo-visual situations. Because surgeons repeatedly touch delicate tissue with their instruments, their depth-perception should not be hampered. Two experiments were performed to evaluate the influence of shadow on human performance when executing stereo-visual pointing tasks. Experiment 1 studied the effect of the existence of shadows and Experiment 2 studied the effect of the direction of shadows. Subjects were instructed to point random sequences of virtual targets accurately under different shadow situations. Performance was characterized with spatial error E (distance to target, mm). Experiment 1 showed that both large and small high-contrast shadows gave significantly smaller spatial error E (4.8, 4.6 mm, respectively) than either low-contrast shadows (5.6 mm) or no shadows (6.3 mm). Experiment 2 showed that the Error varied (2.1 to 3.2 mm) for different illumination directions. The Error decreased with an increasing angle between the line-of-sight and line-of-light. Illuminating from the center or from the left side of the observer gave better results then from the right side. To maximize depth-perception, surgical luminaires should provide a clear shadow from a light source that illuminates from within the vertical plane through the line-of-sight, and with a 90° angle with respect to the line-of-sight. [ABSTRACT FROM AUTHOR]

With the emphasis on laparoscopic skills training outside of the operating room (OR), simulators are constantly being developed and improved. Virtual reality (VR) trainers have been looking for solutions to compensate their lack of haptic feedback. A possible solution is the addition of kinematic interaction between laparoscopic instruments and objects. The aim of the study was to determine whether this interaction can replace haptic feedback that is naturally present in box trainers. Novices (n == 50) were randomly assigned to training in a conventional VR setup (VR-I), a VR environment with additional kinematic interaction (VR-II), a box trainer equivalent of these setups (Box-I or Box-II), or to a control group. An identical cylinder task was performed in all four training setups. The effect was established by comparing the performance before and after training during a tissue handling task, using Wilcoxon signed-rank tests. The controls did not improve significantly. The VR-I group improved in time, whereas VR-II and both box trainer groups improved in time, path length and motion in depth. With respect to haptic feedback, box training models are superior to VR systems. However, additional kinematic interaction between instruments and objects can be a promising surrogate for haptic feedback in VR systems. [ABSTRACT FROM AUTHOR]

In order to fully benefit from the functionalities of flexible endoscopes in surgery a simple shaft-guide that can be used to support the flexible endoscope shaft is required. Such a shaft-guide must be flexible during insertion into the human body and rigidified when properly positioned to support the flexible endoscope shaft. A shaft-guide called 'Vacu-SL' was designed, consisting of a foil tube, filled with particles, that is rigidified by creating a vacuum in its tube. It is expected that the bending stiffness of a loaded, rigidified Vacu-SL shaft-guide is significantly influenced by the shape, hardness and size of the filler particles used. The goal of this study was to find the relations between the filler particles' size, shape and hardness and a rigidified Vacu-SL shaft-guide's bending stiffness. Vacu-SL test models were made using polystyrene, acrylic glass, glass, steel, and corundum particles as spheres, pebbles and granulate, with average diameters between 0.16-1.7 mm. These test models were rigidified and then loaded in a tensile tester. The forces needed for 5 and 10 mm deflections of the rigidified test models were measured. The results show that particle size, shape and hardness all influence a rigidified Vacu-SL shaft-guide's bending stiffness. Size and hardness showed an optimum and granules performed better than spheres. Although the maximally measured bending stiffness might be insufficient to enable proper guidance of flexible endoscope shafts, the results suggest several ways to successfully improve the Vacu-SL shaft-guide. [ABSTRACT FROM AUTHOR]

The article describes how various complementary technologies play a key role in advancing minimally invasive surgical interventions and training simulators in Europe. It examines the tools and systems supporting manipulation controlled by the surgeon, including camera holders to support minimally invasive techniques. Several training methods available to train minimally invasive surgical skills outside the operating room include Pelvitrainers and virtual reality trainers.

Flexible endoscopes [1] are widely used in clinical practice. A flexible endoscope (Figure 1) generally consists of a flexible shaft that contains channels for air, water, instruments, and electric wires. At the distal end of the flexible shaft is a 4?10-cm-long steerable tip. In the tip, there are a digital camera chip, light provided by light emitting diodes (LEDs) or glass fibers, and the exits of air, water, and instrument channels. At the proximal end of the flexible shaft, there is a grip with one or two control wheels or handles that are used to bend the tip in one or two directions. The entrance of the instrument channels are also embodied in the grip and can be used to insert small forceps, needles, or electrocautery instruments with a long flexible shaft through the endoscope shaft. These can then be used to do biopsies or surgeries close to the endoscope tip. [ABSTRACT FROM PUBLISHER]

Little is known about the influence of augmented feedback, on laparoscopic grasp control. To gain more knowledge on the influence of this on the learning curve, two experiments were conducted. In the first experiment, four groups learned a single-handed laparoscopic lifting task. Three groups received augmented feedback (visual, haptic, or a combination of feedback modes) on slip and excessive pinch force. In the second experiment, a two-handed task had to be accomplished to investigate whether paying reduced attention would influence grasp-force control. The surgeons and novices either received tactile feedback or no augmented feedback on grasp forces. In both experiments, learning sessions and a retention test followed a pretest. In the two-handed task, novices who received tactile feedback could control their pinch force in order to remain within the required limits unlike participants who did not receive augmented feedback. Approximately, one-third of the participants who received augmented feedback became dependent on the signal. Regardless of their level of experience, participants benefited from augmented feedback. This research supports the claim that there is a need for augmented tactile feedback when learning laparoscopic grasp control. It enhances learning and goes beyond what could be achieved without. [ABSTRACT FROM PUBLISHER]