Assessment of laparoscopic skills based on force and motion parameters

Functional Data Analysis of Hand Rotation for Open Surgical Suturing Skill Assessment

This study explores the application of functional data analysis (FDA) to hand roll velocity during radial suturing on the SutureCoach bench simulator for evaluating open suturing performance. By treating temporal sensor data as mathematical functions, FDA provides a holistic view of the dynamic changes in hand roll, offering comprehensive assessments that are easily interpretable and clinically relevant. Cluster analysis was performed on hand roll profiles from 96 subjects, categorized into advanced surgeons, trainee surgeons, and novices. Functional k-means, using dynamic time-warping to align curves, were used to partition the data into two preset numbers of clusters (3 and 6). Both clustering models (3-cluster and 6-cluster) effectively clustered performance into groups with distinct characteristics and levels of skill (evident from visual inspection of cluster centroids). The relationship between cluster membership and suturing skills was corroborated using proxy measures of skill: expert global rating scale ratings, clinical status and expertise, and simulator-derived metrics. The findings of this study offer valuable insight into essential components of suturing skill and can improve the autonomy and efficiency of simulation-based suturing training. The clinical relevance of our results is immediately pertinent to the field of surgical skill assessment, where FDA-based methods could potentially be employed for objective feedback and training.

The impact of simulated intra-abdominal movement on basic laparoscopic skills development: a feasibility study

BACKGROUND

Laparoscopic surgery requires a complex set of motor skills. Currently, basic laparoscopic skills training is performed in a static environment, while intraoperatively, abdominal tissue is often moving. The aim of this study was to develop a dynamic training platform and evaluate its impact on laparoscopic skills acquisition in a box trainer.

METHODS

The Dynamic Laparoscopic Platform (DyLaP) includes a moving base which has been intergrated with the Lapron box trainer and the ForceSense objective measurement system. Dynamic training was evaluated in a comparative study where novices were divided into a static and dynamic training group, performing six training trials of a peg transfer task with the DyLaP. Afterwards, both groups performed a dynamic exam task. Task manipulation (force) and instrument efficiency (path length and time) were measured.

RESULTS

Participants (n = 12) exhibited a significant difference (p < 0.05) in time, path length, and maximum force between the static and dynamic groups in the first trial. Learning curves were most prevalent in the dynamic group.

CONCLUSIONS

The DyLaP can be used to provide a challenging and realistic training environment. From the comparative peg transfer study, it can be concluded that dynamic training significantly affects laparoscopic skill acquisition. More research is needed to evaluate dynamic training effects in force-based training tasks.

A comparative study on trocar configurations and the use of steerable instruments in totally extraperitoneal inguinal hernia surgery training

BACKGROUND

Totally extraperitoneal (TEP) inguinal hernia surgery is a commonly performed but technically challenging procedure with a long learning curve. As TEP can be executed using two different trocar placements: a midline or a triangular configuration, the question remains which one is technically easier to master.

METHODS

In a multicenter crossover-study, medical students were randomised into two groups and executed tasks on a box trainer that measured time, volume and force parameters. Additionally, the study assessed whether the SATA instrument, a steerable laparoscopic instrument that articulates the instrument's tip, would reduce the difficulty of performing the tasks in the midline configuration. After training, all participants executed a first experiment using both trocar configurations, followed by a second experiment executed with steerable and non-steerable instruments in the midline configuration. Subjective and objective performances per condition and learning curves were assessed.

RESULTS

Participants were faster and showed lower peak forces in the triangulated configuration. Learning curve analysis showed a positive improvement in time and path length in the midline configuration. Although participants rated ergonomics and intuitiveness similarly between the instruments, they found the task easier with the SATA instruments, ranking the added value of the steering function as 5 out of 5. Objectively, time and path length showed no significant differences while exerted forces were lower when using conventional instruments.

CONCLUSION

Although the midline configuration is preferred in terms of comfort and posture, the findings indicate that, for inexperienced practitioners, performing TEP surgery in midline configuration is both subjectively and objectively more challenging, highlighting the need for extensive training to overcome its difficulties and possibly shorten its learning curve. Although instruments with additional steering functions were preferred over conventional instruments in the more challenging midline configuration, additional steering complexity did not result in better parameter outcomes, showing the need for more extensive training.

Effects of Real Time Feedback on Novice's Laparoscopic Learning Curve

OBJECTIVE

Analyze the learning curve of medical students when they are trained with a laparoscopic box trainer and are presented with different modes of real-time feedback on their performance in the laparoscopic suturing procedure.

DESIGN

A prospective randomized controlled trial (RTC) was performed. Three groups were proposed: control, visual, and haptic. The block randomization technique was used to assign the participants to one of the three groups. Each group trained the intracorporeal square flat knot task in a standardized FLS box simulator. A total of 11 sessions were programmed for this study: a pre-training session, eight training sessions, a post-training session, and a follow-up session. Measurement of the generated reaction force during the task were taken weekly for the first 10 sessions (pre-training, training, and post-training); then, the follow-up measurement was taken a month after.

SETTING

This study was carried out in a single center at the Unidad de Simulación de Posgrado (USIP) of the postgraduate medicine program of the Universidad Nacional Autónoma de México (UNAM) between May and August 2023.

PARTICIPANTS

The eligible participants were medical students without experience in minimally invasive surgery. All social service intern medics doing their social service in the USIP were invited to participate. A total of 20 participants entered the study from which 18 of them finished all the programmed sessions.

RESULTS

A total of ten metrics were extracted from the reaction force signal measured at each session. All metrics are directly proportional to the reaction force and low magnitudes imply high tissue-handling proficiency. All groups improved their tissue handling skills, being the visual group the one who achieved better performance, followed by the haptic group and lastly the control group.

CONCLUSION

The use of real time feedback, especially visual feedback can help novices to shorten the learning process of tissue handling and achieve a better proficiency in advanced tasks in shorter training periods.

Assessment of Open Surgery Suturing Skill: Image-based Metrics Using Computer Vision

OBJECTIVE

This paper presents a computer vision algorithm for extraction of image-based metrics for suturing skill assessment and the corresponding results from an experimental study of resident and attending surgeons.

DESIGN

A suturing simulator that adapts the radial suturing task from the Fundamentals of Vascular Surgery (FVS) skills assessment is used to collect data. The simulator includes a camera positioned under the suturing membrane, which records needle and thread movement during the suturing task. A computer vision algorithm processes the video data and extracts objective metrics inspired by expert surgeons' recommended best practice, to "follow the curvature of the needle."

PARTICIPANTS AND RESULTS

Experimental data from a study involving subjects with various levels of suturing expertise (attending surgeons and surgery residents) are presented. Analysis shows that attendings and residents had statistically different performance on 6 of 9 image-based metrics, including the four new metrics introduced in this paper: Needle Tip Path Length, Needle Swept Area, Needle Tip Area and Needle Sway Length.

CONCLUSION AND SIGNIFICANCE

These image-based process metrics may be represented graphically in a manner conducive to training. The results demonstrate the potential of image-based metrics for assessment and training of suturing skill in open surgery.

Design and preliminary validation of a high-fidelity vascular simulator for robot-assisted manipulation

The number of robot-assisted minimally invasive surgeries is increasing annually, together with the need for dedicated and effective training. Surgeons need to learn how to address the novel control modalities of surgical instruments and the loss of haptic feedback, which is a common feature of most surgical robots. High-fidelity physical simulation has proved to be a valid training tool, and it might help in fulfilling these learning needs. In this regard, a high-fidelity sensorized simulator of vascular structures was designed, fabricated and preliminarily validated. The main objective of the simulator is to train novices in robotic surgery to correctly perform vascular resection procedures without applying excessive strain to tissues. The vessel simulator was integrated with soft strain sensors to quantify and objectively assess manipulation skills and to provide real-time feedback to the trainee during a training session. Additionally, a portable and user-friendly training task board was produced to replicate anatomical constraints. The simulator was characterized in terms of its mechanical properties, demonstrating its realism with respect to human tissues. Its face, content and construct validity, together with its usability, were assessed by implementing a training scenario with 13 clinicians, and the results were generally positive.

Learning Skill Characteristics From Manipulations

Percutaneous coronary intervention (PCI) has increasingly become the main treatment for coronary artery disease. The procedure requires high experienced skills and dexterous manipulations. However, there are few techniques to model PCI skill so far. In this study, a learning framework with local and ensemble learning is proposed to learn skill characteristics of different skill-level subjects from their PCI manipulations. Ten interventional cardiologists (four experts and six novices) were recruited to deliver a medical guidewire to two target arteries on a porcine model for in vivo studies. Simultaneously, translation and twist manipulations of thumb, forefinger, and wrist are acquired with electromagnetic (EM) and fiber-optic bend (FOB) sensors, respectively. These behavior data are then processed with wavelet packet decomposition (WPD) under 1-10 levels for feature extraction. The feature vectors are further fed into three candidate individual classifiers in the local learning layer. Furthermore, the local learning results from different manipulation behaviors are fused in the ensemble learning layer with three rule-based ensemble learning algorithms. In subject-dependent skill characteristics learning, the ensemble learning can achieve 100% accuracy, significantly outperforming the best local result (90%). Furthermore, ensemble learning can also maintain 73% accuracy in subject-independent schemes. These promising results demonstrate the great potential of the proposed method to facilitate skill learning in surgical robotics and skill assessment in clinical practice.

Introducing a novice surgeon to an experienced robotic gynaecological oncology team: An observational cohort study on the impact of a structured curriculum on outcomes of cervical cancer surgery

OBJECTIVE

To evaluate the effect on patient outcomes when introducing a novice robotic surgeon, trained in accordance with a structured learning curriculum, to an experienced robotic surgery team treating cervical cancer patients.

METHODS

Patients with early-stage cervical cancer who were treated with primary robot-assisted surgery between 2007 and 2019 were retrospectively included. In addition to the 165 patients included in a former analysis, we included a further 61 consecutively treated patients and divided all 226 patients over three groups: early learning phase of 61 procedures without structured training (group 1), experienced phase of 104 procedures (group 2), and the 61 procedures during introduction of a novice with structured training (group 3). Risk-adjusted cumulative sum (RA-CUSUM) analysis was performed to assess the learning curve effect. Patient outcomes between the groups were compared.

RESULTS

Based on RA-CUSUM analysis, no learning curve effect was observed for group 3. Regarding surgical outcomes, mean operation time in group 3 was significantly shorter than group 1 (p < 0.001) and similar to group 2 (p = 0.96). Proportions of intraoperative and postoperative adverse events in group 3 were not significantly different from the experienced group (group 2). Regarding oncological outcomes, the 5-year disease-free survival, disease-specific survival, and overall survival in group 3 were not significantly different from the experienced group.

CONCLUSIONS

Introducing a novice robotic surgeon, who was trained in accordance with a structured learning curriculum, resulted in similar patient outcomes as by experienced surgeons suggesting novices can progress through a learning phase without compromising outcomes of cervical cancer patients.

Crossover-effects in technical skills between laparoscopy and robot-assisted surgery

INTRODUCTION

Robot-assisted surgery is often performed by experienced laparoscopic surgeons. However, this technique requires a different set of technical skills and surgeons are expected to alternate between these approaches. The aim of this study is to investigate the crossover effects when switching between laparoscopic and robot-assisted surgery.

METHODS

An international multicentre crossover study was conducted. Trainees with distinctly different levels of experience were divided into three groups (novice, intermediate, expert). Each trainee performed six trials of a standardized suturing task using a laparoscopic box trainer and six trials using the da Vinci surgical robot. Both systems were equipped with the ForceSense system, measuring five force-based parameters for objective assessment of tissue handling skills. Statistical comparison was done between the sixth and seventh trial to identify transition effects. Unexpected changes in parameter outcomes after the seventh trial were further investigated.

RESULTS

A total of 720 trials, performed by 60 participants, were analysed. The expert group increased their tissue handling forces with 46% (maximum impulse 11.5 N/s to 16.8 N/s, p = 0.05), when switching from robot-assisted surgery to laparoscopy. When switching from laparoscopy to robot-assisted surgery, intermediates and experts significantly decreased in motion efficiency (time (sec), resp. 68 vs. 100, p = 0.05, and 44 vs. 84, p = 0.05). Further investigation between the seventh and ninth trial showed that the intermediate group increased their force exertion with 78% (5.1 N vs. 9.1 N, p = 0.04), when switching to robot-assisted surgery.

CONCLUSION

The crossover effects in technical skills between laparoscopic and robot-assisted surgery are highly depended on the prior experience with laparoscopic surgery. Where experts can alternate between approaches without impairment of technical skills, novices and intermediates should be aware of decay in efficiency of movement and tissue handling skills that could impact patient safety. Therefore, additional simulation training is advised to prevent from undesired events.

Objective measurement of retention of laparoscopic skills: a prospective cohort study

INTRODUCTION

There has been an overall growth of 462% in laparoscopic procedures performed by surgical residents between 2000 and 2018. Therefore, training courses in laparoscopic surgery are advocated in many postgraduate programs. While the immediate effect is determined in some cases, the retention of acquired skills is rarely investigated. The objective of this study was to objectively measure the retention of laparoscopic technical skills to offer a more personalized training program.

METHODS

First year general surgery residents performed two fundamental laparoscopic skills tasks (Post and Sleeve and the ZigZag loop) on the Lapron box trainer. Assessment was performed before, directly after, and 4 months after completing the basic laparoscopy course. Force, motion, and time were the measured variables.

RESULTS

A total of 29 participants were included from 12 Dutch training hospitals and 174 trials were analyzed. The 4 months assessment of the Post and Sleeve showed a significant improvement in force ( P= 0.004), motion ( P ≤0.001), and time ( P ≤0.001) compared to the baseline assessment. The same was true for the ZigZag loop: force ( P ≤0.001), motion ( P= 0.005), and time ( P ≤0.001).Compared to the 4 months assessment, skill deterioration was present for the Post and Sleeve in the mean force ( P= 0.046), max impulse ( P= 0.12), and time ( P= 0.002). For the ZigZag loop, skill decay was observed for force ( P= 0.021), motion ( P= 0.015), and time ( P ≤0.001) parameters.

CONCLUSION

Acquired laparoscopic technical skills decreased 4 months after the basic laparoscopy course. Compared to baseline performance, participants showed significant improvement, however deterioration was observed compared to postcourse measurements. To preserve acquired laparoscopic skills, it is recommended to incorporate maintenance training, preferably with objective parameters, in training curricula.

Tracking and evaluating motion skills in laparoscopy with inertial sensors

BACKGROUND

Analysis of surgical instrument motion is applicable in surgical skill assessment and monitoring of the learning progress in laparoscopy. Current commercial instrument tracking technology (optical or electromagnetic) has specific limitations and is expensive. Therefore, in this study, we apply inexpensive, off-the-shelf inertial sensors to track laparoscopic instruments in a training scenario.

METHODS

We calibrated two laparoscopic instruments to the inertial sensor and investigated its accuracy on a 3D-printed phantom. In a user study during a one-week laparoscopy training course with medical students and physicians, we then documented and compared the training effect in laparoscopic tasks on a commercially available laparoscopy trainer (Laparo Analytic, Laparo Medical Simulators, Wilcza, Poland) and the newly developed tracking setup.

RESULTS

Eighteen participants (twelve medical students and six physicians) participated in the study. The student subgroup showed significantly poorer results for the count of swings (CS) and count of rotations (CR) at the beginning of the training compared to the physician subgroup (p = 0.012 and p = 0.042). After training, the student subgroup showed significant improvements in the rotatory angle sum, CS, and CR (p = 0.025, p = 0.004 and p = 0.024). After training, there were no significant differences between medical students and physicians. There was a strong correlation between the measured learning success (LS) from the data of our inertial measurement unit system (LS_IMU) and the Laparo Analytic (LS_Lap) (Pearson's r = 0.79).

CONCLUSION

In the current study, we observed a good and valid performance of inertial measurement units as a possible tool for instrument tracking and surgical skill assessment. Moreover, we conclude that the sensor can meaningfully examine the learning progress of medical students in an ex-vivo setting.

Force-based assessment of tissue handling skills in simulation training for robot-assisted surgery

INTRODUCTION

Although robotic-assisted surgery is increasingly performed, objective assessment of technical skills is lacking. The aim of this study is to provide validity evidence for objective assessment of technical skills for robotic-assisted surgery.

METHODS

An international multicenter study was conducted with participants from the academic hospitals Heidelberg University Hospital (Germany, Heidelberg) and the Amsterdam University Medical Centers (The Netherlands, Amsterdam). Trainees with distinctly different levels of robotic surgery experience were divided into three groups (novice, intermediate, expert) and enrolled in a training curriculum. Each trainee performed six trials of a standardized suturing task using the da Vinci Surgical System. Using the ForceSense system, five force-based parameters were analyzed, for objective assessment of tissue handling skills. Mann-Whitney U test and linear regression were used to analyze performance differences and the Wilcoxon signed-rank test to analyze skills progression.

RESULTS

A total of 360 trials, performed by 60 participants, were analyzed. Significant differences between the novices, intermediates and experts were observed regarding the total completion time (41 s vs 29 s vs 22 s p = 0.003), mean non zero force (29 N vs 33 N vs 19 N p = 0.032), maximum impulse (40 Ns vs 31 Ns vs 20 Ns p = 0.001) and force volume (38 N³ vs 32 N³ vs 22 N³ p = 0.018). Furthermore, the experts showed better results in mean non-zero force (22 N vs 13 N p = 0.015), maximum impulse (24 Ns vs 17 Ns p = 0.043) and force volume (25 N³ vs 16 N³ p = 0.025) compared to the intermediates (p ≤ 0.05). Lastly, learning curve improvement was observed for the total task completion time, mean non-zero force, maximum impulse and force volume (p ≤ 0.05).

CONCLUSION

Construct validity for force-based assessment of tissue handling skills in robot-assisted surgery is established. It is advised to incorporate objective assessment and feedback in robot-assisted surgery training programs to determine technical proficiency and, potentially, to prevent tissue trauma.

Barcodes as Optical Marks for an Objective Assessment of Laparoscopic Skills in a Box Trainer

Background/Need. The sensor-equipped box trainers can objectively evaluate psychomotor skills similar to virtual simulators. However, such box models are least of all involved in curricula in minimally invasive surgery, probably because of their complexity or high cost. This discrepancy prompted us to find a simple solution that provides an objective assessment of laparoscopic skills on any box trainer. Methodology and Device Description. We used QR code, Code 128, and Circular Code 128 as optical marks in tasks on box trainers. These were marks of errors and positive actions. Polyvinylchloride and a nontransparent silicone sheet served as materials for the tasks. All barcode images were printed with black ink on office paper. In addition, we have developed an app that allows dealing with selected types of barcodes. Preliminary results. We designed 6 tasks based on our approach. Every task provides a precision registration of time, errors, and correct actions, comparable with virtual simulators. However, only 4 tasks showed satisfactory results during face validity's obtaining. We found that primitive barcode scanning technology can provide an objective assessment of trainees on box trainers. The proposed approach is well suited for both commercial and custom box trainers. Current status. The research is currently underway to establish construct validity for the developed tasks. Besides, we intend to study features of other types of barcodes, such as Aztec Code, EAN-8, DataMatrix, and annular barcodes.

Prediction of laparoscopic skills: objective learning curve analysis

INTRODUCTION

Prediction of proficiency of laparoscopic skills is essential to establish personalized training programs. Objective assessment of laparoscopic skills has been validated in a laparoscopic box trainer with force, motion and time recognition. The aim of this study is to investigate whether acquiring proficiency of laparoscopic skills can be predicted based on performance in such a training box.

METHODS

Surgical residents in their first year of training performed six different tasks in the Lapron box trainer. Force, motion and time data, three objective measures of tissue manipulation and instrument handling, were collected and analyzed for the six different tasks. Linear regression tests were used to predict the learning curve and the number of repetitions required to reach proficiency.

RESULTS

A total of 6010 practice sessions performed by 42 trainees from 13 Dutch hospitals were assessed and included for analysis. Proficiency level was determined as a mean result of seven experts performing 42 trials. Learning curve graphs and prediction models for each task were calculated. A significant relationship between force, motion and time during six different tasks and prediction of proficiency was present in 17 out of 18 analyses.

CONCLUSION

The learning curve of proficiency of laparoscopic skills can accurately be predicted after three repetitions of six tasks in a training box with force, path length and time recognition. This will facilitate personalized training programs in laparoscopic surgery.

Assessment of open surgery suturing skill: Simulator platform, force-based, and motion-based metrics

Objective

This paper focuses on simulator-based assessment of open surgery suturing skill. We introduce a new surgical simulator designed to collect synchronized force, motion, video and touch data during a radial suturing task adapted from the Fundamentals of Vascular Surgery (FVS) skill assessment. The synchronized data is analyzed to extract objective metrics for suturing skill assessment.

Methods

The simulator has a camera positioned underneath the suturing membrane, enabling visual tracking of the needle during suturing. Needle tracking data enables extraction of meaningful metrics related to both the process and the product of the suturing task. To better simulate surgical conditions, the height of the system and the depth of the membrane are both adjustable. Metrics for assessment of suturing skill based on force/torque, motion, and physical contact are presented. Experimental data are presented from a study comparing attending surgeons and surgery residents.

Results

Analysis shows force metrics (absolute maximum force/torque in z-direction), motion metrics (yaw, pitch, roll), physical contact metric, and image-enabled force metrics (orthogonal and tangential forces) are found to be statistically significant in differentiating suturing skill between attendings and residents.

Conclusion and significance

The results suggest that this simulator and accompanying metrics could serve as a useful tool for assessing and teaching open surgery suturing skill.

Application of an Optical Tracking System for Motor Skill Assessment in Laparoscopic Surgery

Objective

Motion analysis of surgical instruments can be used to evaluate laparoscopic surgical skills, and this study assessed the validity of an optical tracking system for the assessment of laparoscopic surgical motor skills.

Methods

Ten experienced surgeons and ten novices were recruited to complete the transferring tasks on a laparoscopic simulator. An optical tracking system, Micron Tracker, was used to capture the marker points on each instrument and to obtain the coordinates of the marker points and the corresponding instrument tip coordinates. The data are processed to create a coordinate system based on the laparoscopic simulator and to calculate the movement parameters of the instruments, such as operating time, path length, speed, acceleration, and smoothness. At the same time, the range of motion of the instrument (insertion depth and pivoting angle) is also calculated.

Results

The position that the tip of the instrument can reach is a small, irregularly shaped spatial area. Significant differences (p < 0.05) were found between the surgeon and novice groups in parameters such as operating time, path length, mean speed, mean acceleration, and mean smoothness. The range of insertion depth of the instruments was approximately 150 mm to 240 mm, and the pivoting angles of the left and right instruments were 30.9° and 46.6° up and down and 28.0° and 35.0° left and right, respectively.

Conclusions

The optical tracking system was effective in subjectively evaluating laparoscopic surgical skills, with significant differences between the surgeon and novice groups in terms of movement parameters, but not in terms of range of motion.

Safe implementation of hand held steerable laparoscopic instruments: a survey among EAES surgeons

The complexity of handheld steerable laparoscopic instruments (SLI) may impair the learning curve compared to conventional instruments when first utilized. This study aimed to provide the current state of interest in the use of SLI, the current use of these in daily practice and the type of training which is conducted before using SLI in the operating room (OR) on real patients. An online survey was distributed by European Association of Endoscopic Surgery (EAES) Executive Office to all active members, between January 4th and February 3rd, 2020. The survey consisted of 14 questions regarding the usage and training of steerable laparoscopic instruments. A total of 83 members responded, coming from 33 different countries. Twenty three percent of the respondents using SLI, were using the instruments routinely and of these 21% had not received any formal training in advance of using the instruments in real patients. Of all responding EAES members, 41% considered the instruments to potentially compromise patient safety due to their complexity, learning curve and the inexperience of the surgeons. The respondents reported the three most important aspects of a possible steerable laparoscopic instruments training curriculum to be: hands-on training, safe tissue handling and suturing practice. Finally, a major part of the respondents consider force/pressure feedback data to be of significant importance for implementation of training and assessment of safe laparoscopic and robotic surgery. Training and assessment of skills regarding safe implementation of steerable laparoscopic instruments is lacking. The respondents stressed the need for specific hands-on training during which feedback and assessment of skills should be guaranteed before operating on real patients.

Validation of the portable virtual reality training system for robotic surgery (PoLaRS): a randomized controlled trial

BACKGROUND

As global use of surgical robotic systems is steadily increasing, surgical simulation can be an excellent way for robotic surgeons to acquire and retain their skills in a safe environment. To address the need for training in less wealthy parts of the world, an affordable surgical robot simulator (PoLaRS) was designed.

METHODS

The aim of this pilot study is to compare learning curve data of the PoLaRS prototype with those of Intuitive Surgical's da Vinci Skills Simulator (dVSS) and to establish face- and construct validity. Medical students were divided into two groups; the test group (n = 18) performing tasks on PoLaRS and dVSS, and the control group (n = 20) only performing tasks on the dVSS. The performance parameters were Time, Path length, and the number of collisions. Afterwards, the test group participants filled in a questionnaire regarding both systems.

RESULTS

A total of 528 trials executed by 38 participants were measured and included for analyses. The test group significantly improved in Time, Path Length and Collisions during the PoLaRS test phase (P ≤ 0.028). No differences was found between the test group and the control group in the dVSS performances during the post-test phase. Learning curves showed similar shapes between both systems, and between both groups. Participants recognized the potential benefits of simulation training on the PoLaRS system.

CONCLUSIONS

Robotic surgical skills improved during training with PoLaRS. This shows the potential of PoLaRS to become an affordable alternative to current surgical robot simulators. Validation with similar tasks and different expert levels is needed before implementing the training system into robotic training curricula.

A Training Simulator for Fractional Dilation and Curettage With Visualized Force-Position Feedback and Quantitative Evaluation

BACKGROUND

Dilation and curettage (D&C) is a basic, but important procedure with many applications in obstetrics and gynecology. Fractional D&C provides comprehensive sampling of the endocervix and subsequently the uterus. This study designs and validates a novel fractional D&C training simulator visualizing the intrauterine operation in real time and quantitatively assessing technical skills.

METHOD

The fractional D&C training simulator, consisting of measurement hardware and visual software, can display the curette tip's trajectory and force in the uterus in real time. The simulator also presents assessment indices (the cervical coverage index, cervical overlap index, uterine coverage index, uterine overlap index) to indicate the completion degree and quality of surgical performance.

EXPERIENCE

Seventy-five participants with three levels of D&C experience, including 26 novices, 24 intermediates, and 25 experts, were recruited to perform fractional D&C using the training simulator and asked to fill in a postprocedure questionnaire. All assessment indices of the novices were significantly lower than those of experienced surgeons (experts and intermediates) (P<.05). The simulator was highly regarded as a teaching tool and identified frequent areas of incomplete curettage even by experienced surgeons.

CONCLUSION

The fractional D&C training simulator provides valuable visualized force-position feedback and quantitative evaluation and may be beneficial for surgical training.

Comprehensive metrics for evaluating surgical microscope use during tympanostomy tube placement

PURPOSE

Learning to use a surgical microscope is a fundamental step in otolaryngology training; however, there is currently no objective method to teach or assess this skill. Tympanostomy tube placement is a common otologic procedure that requires skilled use of a surgical microscope. This study was designed to (1) implement metrics capable of evaluating microscope use and (2) establish construct validity.

STUDY DESIGN

This was a prospective cohort study.

METHODS

Eight otolaryngology trainees and three otolaryngology experts were asked to use a microscope to insert a tympanostomy tube into a cadaveric myringotomy in a standardized setting. Microscope movements were tracked in a three-dimensional space, and tracking metrics were applied to the data. The procedure was video-recorded and then analyzed by blinded experts using operational metrics. Results from both groups were compared, and discriminatory metrics were determined.

RESULTS

The following tracking metrics were identified as discriminatory between the trainee and expert groups: total completion time, operation time, still time, and jitter (movement perturbation). Many operational metrics were found to be discriminatory between the two groups, including several positioning metrics, optical metrics, and procedural metrics.

CONCLUSIONS

Performance metrics were implemented, and construct validity was established for a subset of the proposed metrics by discriminating between expert and novice participants. These discriminatory metrics could form the basis of an automated system for providing feedback to residents during training while using a myringotomy surgical simulator. Additionally, these metrics may be useful in guiding a standardized teaching and evaluation methodology for training in the use of surgical microscopes.

Assessment of technical skills based on learning curve analyses in laparoscopic surgery training

BACKGROUND

Objective force- and motion-based assessment is currently lacking in laparoscopic skills curricula. This study aimed to evaluate the added value of parameter-based assessment and feedback during training.

METHODS

Laparoscopy-naïve surgical residents that took part in a 3-week skills training curriculum were included. A box trainer equipped with the ForceSense system was used for assessment of tissue manipulation- (MaxForce) and instrument-handling skills (Path length and Time). Learning curves were established using linear regression tests. Pre- and post-course comparisons indicated the overall progression and were compared to predefined proficiency levels. A post-course survey was carried out to assess face validity.

RESULTS

In total, 4,268 trials, executed by 24 residents, were successfully assessed. Median (interquartile range) MaxForce outcomes improved from 2.7 Newton (interquartile range 1.9-3.8) to 1.8 Newton (interquartile range 1.2-2.4) between pre- and post-course assessment (P ≤ .009). Instrument Path length improved from 7,102.2 mm (interquartile range 5,255.2-9,025.9) to 3,545.3 mm (interquartile range 2,842.9-4,563.2) (P ≤.001). Time to execute the task improved from 159.8 seconds (interquartile range 119.8-219.0) to 60.7 seconds (interquartile range 46.0-79.5) (P ≤ .001). The learning curves revealed during what training phase the proficiency benchmarks were reached for each trainee. In the survey outcomes, trainees indicated that this curriculum should be part of a surgical residency program (mean visual analog scale score of 9.2 ± 0.9 standard deviation).

CONCLUSION

Force-, motion-, and time-parameters can be objectively measured during basic laparoscopic skills curricula and do indicate progression of skills over time. The ForceSense parameters enable curricula to be designed for specific proficiency-based training goals and offer the possibility for objective classification of the levels of expertise.

Tool-tissue forces in surgery: A systematic review

Background

Excessive tool-tissue interaction forces often result in tissue damage and intraoperative complications, while insufficient forces prevent the completion of the task. This review sought to explore the tool-tissue interaction forces exerted by instruments during surgery across different specialities, tissues, manoeuvres and experience levels.

Materials & methods

A PRISMA-guided systematic review was carried out using Embase, Medline and Web of Science databases.

Results

Of 462 articles screened, 45 studies discussing surgical tool-tissue forces were included. The studies were categorized into 9 different specialities with the mean of average forces lowest for ophthalmology (0.04N) and highest for orthopaedic surgery (210N). Nervous tissue required the least amount of force to manipulate (mean of average: 0.4N), whilst connective tissue (including bone) required the most (mean of average: 45.8). For manoeuvres, drilling recorded the highest forces (mean of average: 14N), whilst sharp dissection recorded the lowest (mean of average: 0.03N). When comparing differences in the mean of average forces between groups, novices exerted 22.7% more force than experts, and presence of a feedback mechanism (e.g. audio) reduced exerted forces by 47.9%.

Conclusions

The measurement of tool-tissue forces is a novel but rapidly expanding field. The range of forces applied varies according to surgical speciality, tissue, manoeuvre, operator experience and feedback provided. Knowledge of the safe range of surgical forces will improve surgical safety whilst maintaining effectiveness. Measuring forces during surgery may provide an objective metric for training and assessment. Development of smart instruments, robotics and integrated feedback systems will facilitate this.

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This review explores tool-tissue forces during surgery, a new and expanding field.

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Forces were lowest in ophthalmology (0.04N) and highest in orthopaedics (210N).

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Forces were lowest during sharp dissection (0.03N) and highest when drilling (14N).

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Being an expert (vs. novice) and having feedback mechanisms (e.g. haptic) reduced exerted forces.

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Development of force metrics will facilitate training, assessment & novel technology.

Robotic-assisted cholecystectomy is superior to laparoscopic cholecystectomy in the initial training for surgical novices in an ex vivo porcine model: a randomized crossover study

Background

Robotic-assisted surgery (RAS) potentially reduces workload and shortens the surgical learning curve compared to conventional laparoscopy (CL). The present study aimed to compare robotic-assisted cholecystectomy (RAC) to laparoscopic cholecystectomy (LC) in the initial learning phase for novices.

Methods

In a randomized crossover study, medical students (n = 40) in their clinical years performed both LC and RAC on a cadaveric porcine model. After standardized instructions and basic skill training, group 1 started with RAC and then performed LC, while group 2 started with LC and then performed RAC. The primary endpoint was surgical performance measured with Objective Structured Assessment of Technical Skills (OSATS) score, secondary endpoints included operating time, complications (liver damage, gallbladder perforations, vessel damage), force applied to tissue, and subjective workload assessment.

Results

Surgical performance was better for RAC than for LC for total OSATS (RAC = 77.4 ± 7.9 vs. LC = 73.8 ± 9.4; p = 0.025, global OSATS (RAC = 27.2 ± 1.0 vs. LC = 26.5 ± 1.6; p = 0.012, and task specific OSATS score (RAC = 50.5 ± 7.5 vs. LC = 47.1 ± 8.5; p = 0.037). There were less complications with RAC than with LC (10 (25.6%) vs. 26 (65.0%), p = 0.006) but no difference in operating times (RAC = 77.0 ± 15.3 vs. LC = 75.5 ± 15.3 min; p = 0.517). Force applied to tissue was similar. Students found RAC less physical demanding and less frustrating than LC.

Conclusions

Novices performed their first cholecystectomies with better performance and less complications with RAS than with CL, while operating time showed no differences. Students perceived less subjective workload for RAS than for CL. Unlike our expectations, the lack of haptic feedback on the robotic system did not lead to higher force application during RAC than LC and did not increase tissue damage. These results show potential advantages for RAS over CL for surgical novices while performing their first RAC and LC using an ex vivo cadaveric porcine model.

Registration number

researchregistry6029

Graphic abstract

Knowledge representation and learning of operator clinical workflow from full-length routine fetal ultrasound scan videos

Ultrasound is a widely used imaging modality, yet it is well-known that scanning can be highly operator-dependent and difficult to perform, which limits its wider use in clinical practice. The literature on understanding what makes clinical sonography hard to learn and how sonography varies in the field is sparse, restricted to small-scale studies on the effectiveness of ultrasound training schemes, the role of ultrasound simulation in training, and the effect of introducing scanning guidelines and standards on diagnostic image quality. The Big Data era, and the recent and rapid emergence of machine learning as a more mainstream large-scale data analysis technique, presents a fresh opportunity to study sonography in the field at scale for the first time. Large-scale analysis of video recordings of full-length routine fetal ultrasound scans offers the potential to characterise differences between the scanning proficiency of experts and trainees that would be tedious and time-consuming to do manually due to the vast amounts of data. Such research would be informative to better understand operator clinical workflow when conducting ultrasound scans to support skills training, optimise scan times, and inform building better user-machine interfaces. This paper is to our knowledge the first to address sonography data science, which we consider in the context of second-trimester fetal sonography screening. Specifically, we present a fully-automatic framework to analyse operator clinical workflow solely from full-length routine second-trimester fetal ultrasound scan videos. An ultrasound video dataset containing more than 200 hours of scan recordings was generated for this study. We developed an original deep learning method to temporally segment the ultrasound video into semantically meaningful segments (the video description). The resulting semantic annotation was then used to depict operator clinical workflow (the knowledge representation). Machine learning was applied to the knowledge representation to characterise operator skills and assess operator variability. For video description, our best-performing deep spatio-temporal network shows favourable results in cross-validation (accuracy: 91.7%), statistical analysis (correlation: 0.98, p < 0.05) and retrospective manual validation (accuracy: 76.4%). For knowledge representation of operator clinical workflow, a three-level abstraction scheme consisting of a Subject-specific Timeline Model (STM), Summary of Timeline Features (STF), and an Operator Graph Model (OGM), was introduced that led to a significant decrease in dimensionality and computational complexity compared to raw video data. The workflow representations were learnt to discriminate between operator skills, where a proposed convolutional neural network-based model showed most promising performance (cross-validation accuracy: 98.5%, accuracy on unseen operators: 76.9%). These were further used to derive operator-specific scanning signatures and operator variability in terms of type, order and time distribution of constituent tasks.

Objective and automated assessment of surgical technical skills with IoT systems: A systematic literature review

The assessment of surgical technical skills to be acquired by novice surgeons has been traditionally done by an expert surgeon and is therefore of a subjective nature. Nevertheless, the recent advances on IoT (Internet of Things), the possibility of incorporating sensors into objects and environments in order to collect large amounts of data, and the progress on machine learning are facilitating a more objective and automated assessment of surgical technical skills. This paper presents a systematic literature review of papers published after 2013 discussing the objective and automated assessment of surgical technical skills. 101 out of an initial list of 537 papers were analyzed to identify: 1) the sensors used; 2) the data collected by these sensors and the relationship between these data, surgical technical skills and surgeons' levels of expertise; 3) the statistical methods and algorithms used to process these data; and 4) the feedback provided based on the outputs of these statistical methods and algorithms. Particularly, 1) mechanical and electromagnetic sensors are widely used for tool tracking, while inertial measurement units are widely used for body tracking; 2) path length, number of sub-movements, smoothness, fixation, saccade and total time are the main indicators obtained from raw data and serve to assess surgical technical skills such as economy, efficiency, hand tremor, or mind control, and distinguish between two or three levels of expertise (novice/intermediate/advanced surgeons); 3) SVM (Support Vector Machines) and Neural Networks are the preferred statistical methods and algorithms for processing the data collected, while new opportunities are opened up to combine various algorithms and use deep learning; and 4) feedback is provided by matching performance indicators and a lexicon of words and visualizations, although there is considerable room for research in the context of feedback and visualizations, taking, for example, ideas from learning analytics.

Distinguishing Intermediate and Novice Surgeons by Eye Movements

Surgical skill-level assessment is key to collecting the required feedback and adapting the educational programs accordingly. Currently, these assessments for the minimal invasive surgery programs are primarily based on subjective methods, and there is no consensus on skill level classifications. One of the most detailed of these classifications categorize skill levels as beginner, novice, intermediate, sub-expert, and expert. To properly integrate skill assessment into minimal invasive surgical education programs and provide skill-based training alternatives, it is necessary to classify the skill levels in as detailed a way as possible and identify the differences between all skill levels in an objective manner. Yet, despite the existence of very encouraging results in the literature, most of the studies have been conducted to better understand the differences between novice and expert surgical skill levels leaving out the other crucial skill levels between them. Additionally, there are very limited studies by considering the eye-movement behaviors of surgical residents. To this end, the present study attempted to distinguish novice- and intermediate-level surgical residents based on their eye movements. The eye-movement data was recorded from 23 volunteer surgical residents while they were performing four computer-based simulated surgical tasks under different hand conditions. The data was analyzed using logistic regression to estimate the skill levels of both groups. The best results of the estimation revealing a 91.3% recognition rate of predicting novice and intermediate surgical residents on one scenario were selected from four under the dominant hand condition. These results show that the eye-movements can be potentially used to identify surgeons with intermediate and novice skills. However, the results also indicate that the order in which the scenarios are provided, and the design of the scenario, the tasks, and their appropriateness with the skill levels of the participants are all critical factors to be considered in improving the estimation ratio, and hence require thorough assessment for future research.

Ergonomic assessment of a new hand tool design for laparoscopic surgery based on surgeons' muscular activity

Laparoscopic surgery techniques are customarily used in non-invasive procedures. That said traditional surgical instruments and devices used by surgeons suffer from certain ergonomic deficiencies that may lead to physical complaints in upper limbs and back and general discomfort that may, in turn, affect the surgeon's skills during surgery. A novel design of the laparoscopic gripper handle is presented and compared with one of the most used instruments in this field in an attempt to overcome this problem. The assessment of the ergonomic feature of the novel design was performed by using time-frequency analysis of the surface electromyography (sEMG) signal during dynamic activities. Singular Spectrum Analysis (SSA) was used to decompose the sEMG signal and extract the median frequency of each muscle to assess muscle fatigue. The results reveal that using the proposed ergonomic grip reduces the mean values of the muscle activity during each of the proposed tasks. The novel design also improves the ease of use in laparoscopic surgery as it minimises high-pressure contact areas, reduces large amplitude movements and promotes a neutral position of the hand, wrist and forearm. Furthermore, the SSA method for time-frequency analysis provides a powerful tool to analyse a prescribed activity in ergonomic terms. The proposed methodology to assess muscle activity during surgery activities may be useful in the selection of surgical instruments when programming extended procedures, as it provides an additional selection criterion based on the surgeon's biomechanics and the proposed activity.

Haptic exploration improves performance of a laparoscopic training task

BACKGROUND

Laparoscopy has reduced tactile and visual feedback compared to open surgery. There is increasing evidence that visual and haptic information converge to form a more robust mental representation of an object. We investigated whether tactile exploration of an object prior to executing a laparoscopic action on it improves performance.

METHODS

A prospective cohort study with 20 medical students randomized in two different groups was conducted. A silicone ileocecal model, on which a laparoscopic action had to be performed, was used inside an outside a ForceSense box trainer. During the pre-test, students either did a combined manual and visual exploration or only visual exploration of the caecum model. To track performance during the trials of the study we used force, motion and time parameters as representatives of technical skills development. The final trial data were used for statistical comparison between groups.

RESULTS

All included time and motion parameters did not show any clear differences between groups. However, the force parameters Mean force non-zero (p = 004), Maximal force (p = 0.01) Maximal impulse (p = 0.02), Force volume (p = 0.02) and SD force (p = 0.01) showed significant lower values in favour of the tactile exploration group for the final trials.

CONCLUSIONS

By adding haptic sensation to the existing visual information during training of laparoscopic tasks on life-like models, tissue manipulation skills improve during training.

Construct validity of the SurgForce system for objective assessment of laparoscopic suturing skills

BACKGROUND

Laparoscopic surgery requires a new set of skill to be learned by the surgeons, of which the most relevant is tissue manipulation. Excessive forces applied to the tissue can cause rupture during manipulation or ischemia when confronting both sides of the tissue. The aim of this study is to establish the construct validity of the SurgForce system for objective assessment of advanced laparoscopic skills, based on the force signal generated during suture tasks, and the development of force parameters for evaluating tissue handling interaction.

METHODS

The SurgForce system, a tissue handling training device that measures dynamic force, was used to capture the force generated by surgeons with different levels of laparoscopic experience. For construct validity, 37 participants were enrolled in this study: 19 medical students, 12 residents of surgical specialties and 6 expert surgeons. All participants performed an intracorporeal knotting suture task over a synthetic tissue pad with a laparoscopic box-trainer. The force performance of the participants was analyzed using 11 force-based parameters with the application of the SurgForce system. Statistical analysis was performed between novice, intermediate, and expert groups using a Kruskal-Wallis test, and between the pairs of groups using a Mann-Whitney U-test.

RESULTS

Overall, 9 of the 11 force-related parameters showed significant differences between the three study groups. Results between the pairs of groups presented significant differences in 5 force parameters proposed. Construct validity results demonstrated that the SurgForce system was able to differentiate force performance between surgeons with different levels of laparoscopic experience.

CONCLUSION

The SurgForce system was successfully validated. This force system showed its potential to measure the force exerted on tissue for objective assessment of tissue handling skills in suturing tasks. Furthermore, its compact design allows the use of this device in conventional laparoscopic box-trainers.

Design of a Dynamic Force Measurement System for Training and Evaluation of Suture Surgical Skills

The aim of this study is to present the SurgeForce system, a tissue handling training device for analysis of dynamic force applied to the tissue and objective assessment of basic surgical skills during the suture process. The SurgeForce system consists of a mechanical base formed by two platforms joint with three stainless steel springs and a three axial digital accelerometer attached to the upper platform, which detects the dynamic force caused by a surgeon when performing a suture task over a synthetic tissue pad. Accelerometer data is sent to a control unit where preprocessing to transform the raw data into a force signal is done, and then, the force signal is sent to a computer application, which register the force exerted over the synthetic tissue pad. For validation, 17 participants (6 surgeons and 11 medical students) performed three simple interrupted sutures with knot tying using the SurgeForce system. Ten force-based metrics were proposed to evaluate their performance during the suturing task. Results of the validation showed statistical differences in 8 of 10 force-based parameters for assessment of basic surgical skills during the suture task. The SurgeForce system demonstrated its capacity to differentiate force-based performance of surgeons and medical students. The SurgeForce system has been successfully validated. This system was able to distinguish force performance between experts and novices, showing its potential to distinguish surgeons with basic suture skills from those who are not yet prepared.

Motion Control and External Force Estimation of a Pneumatically Driven Multi-DOF Robotic Forceps

Robotic forceps with a rigid-link joint mechanism is orthodox for current robotic-assisted surgery systems. However, external force estimation without force sensors during operations is difficult for such electrically driven forceps. This work introduces a pneumatically driven multi-DOF (DOF: degree of freedom) forceps using a rigid-link mechanism with less interference of the wire drive between joints and realizes external force estimation by utilizing high back-drivability of pneumatic cylinders. We developed a position controller with dynamic compensation of the mechanical friction, in which the rotational angles of the three movable joints of the forceps are independently controlled. Moreover, we designed an external force observer in the position controller by applying the disturbance observer scheme. The results of the performance evaluation experiments are as follows. First, in the joint position control experiments, smooth and stable controllability is confirmed for sinusoidal reference inputs with the mean absolute errors of less than 2°. The resolution of the joint position control is approximately 1° for the response of step increasing reference inputs, which is acceptable for laparoscopic surgery. Second, the external force observer can correctly estimate the translational and the grasping forces with less than 20% errors of the maximum output forces. The practical sensitivities of the external force estimation are better than 0.5 N for translational forces and 0.2 N for grasping forces. The achieved performance of the developed forceps can be applicable for interactive force control in some particular surgical tasks such as suturing, ligation, organ traction and exclusion.

Comparative Study of the Use of Different Sizes of an Ergonomic Instrument Handle for Laparoscopic Surgery

Previous studies have shown that the handle design of laparoscopic instruments is crucial to surgical performance and surgeon’s ergonomics. In this study, four different sizes of an ergonomic laparoscopic handle design were tested in a blind and randomized fashion with twelve surgeons. They performed three laparoscopic tasks in order to analyze the influence of handle size. Execution time, wrist posture, and finger and palm pressure were evaluated during the performance of each task. The results show a significant reduction in the time required to complete the eye-manual coordination task using the appropriate handle. The incorrectly sized handle resulted in a rise in palm pressure and a reduction in the force exerted by the thumb during the transfer task. In the hand-eye coordination task, the use of the right handle size led to an increase in middle finger pressure. In general, surgeons had an ergonomically adequate wrist flexion in all tasks and an acceptable radio-ulnar deviation during the transfer task using the ergonomic instrument handle. Surgeons found it comfortable the use of the ergonomic handle. Therefore, the use of an appropriately sized instrument handle allows surgeons to improve ergonomics and surgical performance during the laparoscopic practice.

Surgical Suturing with Depth Constraints: Image-based Metrics to Assess Skill

Suturing is one of the most fundamental surgical skills, requiring careful and systematic instruction for skilled performance. In this paper, we evaluate the performance of attending surgeons and surgical residents on an open surgery suturing task to examine if the introduction of different depth levels affects their performance. A vision algorithm is used to extract metrics meaningful in the assessment of suturing skill. As subjects perform a suturing task on the platform, our vision algorithm computes metrics identified to be potentially useful in assessing suturing skill: distances from optimal entry and optimal exit points, stitch length, stitch time, idle time, needle swept area, needle tip trace distance, needle tip area, and needle sway length. Preliminary experimental data from a study with 5 attending surgeons and 7 surgical residents are presented. Results demonstrate that the metrics of distance from optimal exit points, idle time, needle swept area, needle tip trace distance, needle tip area, and needle sway length are useful in quantifying the effect of depth constraints on suturing performance.

The value of force and torque measurements in transanal total mesorectal excision (TaTME)

Background

Transanal total mesorectal excision (TaTME) is associated with a relatively long learning curve. Force, motion, and time parameters are increasingly used for objective assessment of skills to enhance laparoscopic training efficacy. The aim of this study was to identify relevant metrics for accurate skill assessment in more complex transanal purse-string suturing.

Methods

A box trainer was designed for TaTME and equipped with two custom made multi-DOF force/torque sensors. These sensors measured the applied forces in the axial direction of the instruments (Fz), instrument load orientation expressed in torque (Mx and My) on the entrance port, and the full tissue interaction force (Fft) at the intestine fixation point. In a construct validity study, novices for TaTME performed a purse-string suture to investigate which parameters can be used best to identify meaningful events during tissue manipulation and instrument handling.

Results

Significant differences exist between pre- and post-training assessment for the mean axial force at the entrance port Fz (p = 0.01), mean torque in the entrance port Mx (p = 0.03) and mean force on the intestine during suturing Fft (p = 0.05). Furthermore, force levels during suturing exceed safety threshold values, potentially leading to dangerous complications such as rupture of the rectum.

Conclusions

Forces and torque measured at the entrance port, and the tissue interaction force signatures provide detailed insight into instrument handling, instrument loading, and tissue handling during purse-string suturing in a TaTME training setup. This newly developed training setup for single-port laparoscopy that enables objective feedback has the potential to enhance surgical training in TaTME.

A new modular mechanism that allows full detachability and cleaning of steerable laparoscopic instruments

Background

Ever since the introduction of laparoscopic surgery, researchers have been trying to add steerability to instruments to allow the surgeon to operate with better reachability and less tissue interaction force. Traditional solutions to introduce this often use a combination of springs, cables, pulleys, and guiding structures, resulting in instruments that cannot be properly cleaned and thus are very costly to manufacture and maintain. The aim of the study is to develop a novel affordable, sustainable, cableless, and fully steerable laparoscopic grasper, and to test its ease of assembly, disassembly, and use.

Methods

A set of requirements was defined to ensure that the instrument can be handled efficiently at the sterilization unit and in the operating room. Based on these, a multisteerable, cableless 5 mm laparoscopic instrument that operates based on shaft rotations was developed. To test its assembly and disassembly, ten participants were asked to fully dismantle the instrument and reassemble it a total of 60 times. In addition, ten medical students were asked to use the grasper in the ForceSense box-trainer system on a newly developed 3D pick-and-place task, to determine the control effort based on learning curves of steering errors, task time, instrument path length, and maximum tissue interaction force.

Results

All important design requirements were met. The recorded data indicates that ten engineering students were able to fully dismantle and reassemble the instrument shaft in 12 s (SD7) and 65 s (SD43) seconds at the sixth attempt. The learning-curve data indicates that three attempts were needed before the ten medical students started to use all steering functions. At the sixth attempt, on average only 1.25 (SD0.7) steering errors were made. The steepest slope in the learning curves for steering errors, path length, and task time was experienced during the first three attempts. In respect of the interaction force, no learning effect was observed.

Conclusion

The multi-DOF (degree of freedom) cableless grasper can be assembled and disassembled for cleaning and sterilization within an acceptable time frame. The handle interface proved to be intuitive enough for novices to conduct a complex 3D pick-and-place task in a training setting.

Electronic supplementary material

The online version of this article (10.1007/s00464-019-06849-0) contains supplementary material, which is available to authorized users.

Qualitative and Quantitative Assessment of Technical Skills in Percutaneous Coronary Intervention: In Vivo Porcine Studies

OBJECTIVE

Technical skill assessment plays an important role in the professional development of an interventionalist in percutaneous coronary intervention (PCI). However, most of the traditional assessment methods are time consuming and subjective. This paper aims to develop objective assessment techniques.

METHODS

In this study, a natural-behavior-based assessment framework is proposed to qualitatively and quantitatively assess technical skills in PCI. In vivo porcine studies were conducted to deliver a medical guidewire to two target coronaries of left circumflex arteries by six novice and four expert interventionalists. Simultaneously, four types of natural behaviors (i.e., hand motion, proximal force, muscle activity, and finger motion) were acquired from the subjects' dominant hand and arm. The features extracted from the behaviors of different skill-level groups were compared using the Mann-Whitney U-test for effective behavior selection. The effective ones were further applied in the Gaussian-mixture-model-based qualitative assessment and Mahalanobis-distance-based quantitative assessment.

RESULTS

The qualitative assessment achieves an accuracy of 92% to distinguish the novice and expert attempts, which is significantly higher than that of using single guidewire motions. Furthermore, the quantitative assessment can assign objective and effective scores for all attempts, indicating high correlation ( R = 0.9225) to those obtained by traditional methods.

CONCLUSION

The objective, effective, and comprehensive assessment of technical skills can be provided by qualitatively and quantitatively analyzing interventionalists' natural behaviors in PCI.

SIGNIFICANCE

This paper suggests a novel approach for the technical skill assessment and the promising results demonstrate the great importance and effectiveness of the proposed method for promoting the development of objective assessment techniques.

Pneumatically driven surgical instrument capable of estimating translational force and grasping force

BACKGROUND

In robot-assisted minimally invasive surgery, feedback as well as sensing of translational and grasping forces allows surgeons to manipulate the robots using an appropriate force. However, there have been limited reports on single instruments capable of sensing both forces (translational force and grasping force), with the exception of instruments with electronic sensors.

METHODS

In this study, a pneumatically driven surgical instrument capable of estimating both translational and grasping forces is developed. Our estimation method is based on the dynamics and pneumatic pressure changes of the instrument. For each force estimation, we applied a joint mechanism consisting of disks and a flexible backbone and constructed pneumatic driving systems, kinematic models, dynamic models, controller, and force estimator.

RESULTS

We confirmed experimentally that the mean absolute error between the measured forces and the estimated translational and grasping forces is 0.2 N or less for any condition. From these results, it is seen that the mechanical interference between the joint actuation mechanism and grasper actuation mechanism is negligibly small.

CONCLUSIONS

A method for estimating both forces was proposed, and experimental results confirmed the effectiveness of the method.

Haptic Feedback, Force Feedback, and Force-Sensing in Simulation Training for Laparoscopy: A Systematic Overview

OBJECTIVES

To provide a systematic overview of the literature assessing the value of haptic and force feedback in current simulators teaching laparoscopic surgical skills.

DATA SOURCES

The databases of Pubmed, Cochrane, Embase, Web of Science, and Google Scholar were searched to retrieve relevant studies published until January 31st, 2017. The search included laparoscopic surgery, simulation, and haptic or force feedback and all relevant synonyms.

METHODS

Duplicates were removed, and titles and abstracts screened. The remaining articles were subsequently screened full text and included in this review if they followed the inclusion criteria. A total of 2 types of feedback have been analyzed and will be discussed separately: haptic- and force feedback.

RESULTS

A total of 4023 articles were found, of which 87 could be used in this review. A descriptive analysis of the data is provided. Results of the added value of haptic interface devices in virtual reality are variable. Haptic feedback is most important for more complex tasks. The interface devices do not require the highest level of fidelity. Haptic feedback leads to a shorter learning curve with a steadier upward trend. Concerning force feedback, force parameters are measured through force sensing systems in the instrument and/or the environment. These parameters, especially in combination with motion parameters, provide box trainers with an objective evaluation of laparoscopic skills. Feedback of force-use both real time and postpractice has been shown to improve training.

CONCLUSIONS

Haptic feedback is added to virtual reality simulators to increase the fidelity and thereby improve training effect. Variable results have been found from adding haptic feedback. It is most important for more complex tasks, but results in only minor improvements for novice surgeons. Force parameters and force feedback in box trainers have been shown to improve training results.

Assessment of distal access catheter performance during neuroendovascular procedures: measuring force in three-dimensional patient specific phantoms

BACKGROUND

The amount of force applied on a device is an important measure to evaluate the endovascular and surgical device manipulations. The measure has not been evaluated for neuroenodvascular procedures.

PURPOSE

We aimed to study the use of force measure as a novel approach to test distal access catheter (DAC) performance during catheterization of cervical and intracranial vessels using patient specific 3-dimentional (3D) phantoms.

METHODS

Using patient specific 3D phantoms of the cervical and intracranial circulation, we recorded measure of force required to deliver three types of DACs beyond the ophthalmic segment of the internal carotid artery. Six different combinations of DAC-microcatheter-guidewire were tested. We intentionally included what we considered suboptimal combinations of DACs, microcatheters, and guidewires during our experiments to test the feasibility of measuring force under different conditions. A six axis force sensor was secured to the DAC with an adjustable torque used to track axially directed push and pull forces required to navigate the DAC to the target site.

RESULTS

In a total of 55 experiments, we found a significant difference in the amount of force used between different DACs (mean force for DAC A, 1.887±0.531N; for DAC B, 2.153±1.280 N; and for DAC C, 1.194±0.521 N, P=0.007). There was also a significant difference in force measures among the six different catheter systems (P=0.035).

CONCLUSIONS

Significant difference in the amount of force used between different DACs and catheter systems were recorded. Use of force measure in neuroendovascular procedures on 3D printed phantoms is feasible.

The Impact of Simulator Size on Forces Generated in the Performance of a Defined Intracorporeal Suturing Task: A Pilot Study

Background: In pediatric minimal access surgery, the operative domain may vary from that of an adult to that of a neonate. This study aimed to quantify the impact of decreased operative domain on forces generated in the performance of a defined intracorporeal suturing task. Methods: One hundred five participants performed a defined intracorporeal suturing task in small and large simulators. Time to task completion and force analysis parameters (FAPs = total, maximum, and mean forces in X, Y, and Z axes) were measured. Expertise level was assigned based on the number of laparoscopic cases. Outcomes were analyzed using paired sample t-tests, P value of <.05. Results: Time to task completion varied significantly for experts between adult and pediatric simulators but not for intermediates or novices. Total, maximum, and mean forces in the X ("side to side") axis were significantly greater in the larger laparoscopic simulator for all levels of expertise. In the Y axis ("in and out" movement) and Z axis ("up and down" movement), total and mean forces were higher in the adult simulator regardless of the level of expertise. Differences in maximum force between the adult and pediatric simulators in the Z axis ("up and down" movement) varied significantly for novices and intermediates but not for experts. Conclusion: Forces were greater, particularly in the side-to-side plane, in the larger simulator for participants of all levels in the performance of this defined intracorporeal suturing task. Further analysis will determine the reasons for and implications of the increased force parameters in the simulator of larger domain.

Development of an Open-Source Laparoscopic Simulator Capable of Motion and Force Assessment: High Tech at Low Cost

OBJECTIVE

Laparoscopic simulators help improve surgical skills in an ex vivo setting. New simulators incorporate force and motion assessment, but often at high financial cost. Our goal is to establish global access to a laparoscopic simulator, which offers both traditional summative assessment (time to task completion and precision) as well as advanced formative assessment (force and motion sensing capabilities) so that educators anywhere may be able to create simulators with increased educational value.

DESIGN

A low-cost laparoscopic simulator incorporating an off-the-shelf optical sensor, inertial measurement unit, holders, and a housing unit for a microcontroller was integrated into a plastic box with a high-definition digital camera and a three-dimensional mouse. Open source software was developed to offer real-time feedback in force and motion. The system was calibrated for accuracy and consistency.

RESULTS

The simulator was assembled from off-the-shelf components and open-source software. Total estimated cost was $350 United States Dollars. The mouse was calibrated by applying known forces in known directions. Linear forces measured in all axes showed linear output trends with r²-values of between 0.988 and 0.999. Accuracy in motion evaluation was evaluated and this demonstrated low average errors in the motion sensors of 5.4% to 6.8%.

CONCLUSIONS

This low-cost, off-the-shelf, open-access laparoscopic simulator provides accurate and consistent measures of force and motion. We believe that collaborative efforts between surgeons and engineers can allow the creation of these surgical teaching devices at a reasonable cost such that they can be used in resource-rich and resource-limited settings.

Evaluating Fitness to Perform in Surgical Residents after Night Shifts and Alcohol Intoxication: The development of a "Fit-to-Perform" test

OBJECTIVE

To develop a self-test to measure clinical fitness to perform in surgical residents, with alcohol-induced impairment as reference.

DESIGN

Observational, exploratory study to evaluate night shift-induced impaired performance in surgical residents followed by a randomized blinded, placebo-controlled, crossover study to evaluate impaired performance as a result of ethanol intoxication. Impairment was quantified using the Mini-NeuroCart, a psychomotor and cognitive test battery for assessment of subjective and objective measures of alertness, concentration, eye-hand coordination, mood, and self-assessed ability to perform. Surgical performance was tested in the randomized study with a laparoscopy surgical trainer.

SETTINGS

Level-I trauma hospital and a clinical research unit.

PARTICIPANTS

Surgical residents (n = 12 for the observational study, n = 18 for the randomized study).

RESULTS

High alcohol levels (0.6gL^-1) impaired adaptive tracking, reduced objective and subjective alertness, and increased slowness. Moreover, laparoscopy depth perception was impaired in the 0.6gL^-1 group. No significant within-subject correlation between subjective and objective measures of alertness was found. Performance of postcall surgeons was similar to, or even worse than, the performance of intoxicated surgeons.

CONCLUSIONS

The Mini-NeuroCart detected ethanol-induced performance effects that were similar to the effects of working a 14-hour night shift. Social (ethanol), personal (mood), and professional (laparoscopic skills) standards of fitness can in this manner be related to accepted deleterious effects of alcohol. The Mini-NeuroCart is, therefore, a potential noninvasive test for assessing "fitntness to perform" in healthcare professionals.

Proof of Concept Study: Investigating Force Metrics of an Intracorporeal Suturing Knot Task

BACKGROUND

Mastering proper force manipulation in minimally invasive surgery can take many hours of practice and training. Improper force control can lead to necrosis, infection, and scarring. A force-sensing skin (FSS) has been developed, which measures forces at the distal end of minimal access surgeries' (MAS) instruments without altering the instrument's structural integrity or the surgical workflow, and acts as a minimally disruptive add-on to any MAS instrument.

METHODS

A proof of concept study was conducted using a FSS-equipped 5 mm straight-tip needle holder. Participants (n = 19: 3 novices, 11 fellows, and 5 staff surgeons) performed one intracorporeal suturing knot task (ISKT). Using participant task video footage, each participant's two puncture forces (each wall of the Penrose drain) and three knot tightening forces were measured. Force metrics from the three expertise groups were compared using analysis of variance (ANOVA) and Tukey's honest significance test with statistical significance assessed at P < .05.

RESULTS

Preliminary ISKT force metric data showed differences between novices and more experienced fellows and surgeons. Of the five stages of the ISKT evaluated, the first puncture force of the Penrose drain seemed to best reflect the difference in skill among participants. The study demonstrated ISKT knot tightening and puncture force ranges across three expertise levels (novices, surgical fellows, and staff surgeons) of 0.586 to 6.089 newtons (N) and 0.852 to 2.915 N, respectively.

CONCLUSION

The investigation of force metrics is important for the implementation of future force feedback systems as it can provide real-time information to surgeons in training and the operating theater.

Face and Construct Validity of a Novel Virtual Reality-Based Bimanual Laparoscopic Force-Skills Trainer With Haptics Feedback

BACKGROUND

The purpose of this study was to examine the face and construct validity of a custom-developed bimanual laparoscopic force-skills trainer with haptics feedback. The study also examined the effect of handedness on fundamental and complex tasks.

METHODS

Residents (n = 25) and surgeons (n = 25) performed virtual reality-based bimanual fundamental and complex tasks. Tool-tissue reaction forces were summed, recorded, and analysed. Seven different force-based measures and a 1-time measure were used as metrics. Subsequently, participants filled out face validity and demographic questionnaires.

RESULTS

Residents and surgeons were positive on the design, workspace, and usefulness of the simulator. Construct validity results showed significant differences between residents and experts during the execution of fundamental and complex tasks. In both tasks, residents applied large forces with higher coefficient of variation and force jerks (P < .001). Experts, with their dominant hand, applied lower forces in complex tasks and higher forces in fundamental tasks (P < .001). The coefficients of force variation (CoV) of residents and experts were higher in complex tasks (P < .001). Strong correlations were observed between CoV and task time for fundamental (r = 0.70) and complex tasks (r = 0.85). Range of smoothness of force was higher for the non-dominant hand in both fundamental and complex tasks.

CONCLUSIONS

The simulator was able to differentiate the force-skills of residents and surgeons, and objectively evaluate the effects of handedness on laparoscopic force-skills. Competency-based laparoscopic skills assessment curriculum should be updated to meet the requirements of bimanual force-based training.

Design and Validation of a Three-Dimensional Printed Flexible Canine Otoscopy Teaching Model

Introduction

A teaching model was sought to improve canine otoscopy skill and reduce use of teaching dogs.

Methods

An otoscopy teaching model was printed in a flexible medium on a desktop three-dimensional printer from a magnetic resonance image of a canine external ear canal. The model was mounted in a polyvinyl dog mannequin. Validation of the teaching model was sought from student, faculty, and dog perspective. Student perception of prelaboratory training was assessed using a survey regarding their experience. Otoscopy skill was assessed by faculty grading the ear anatomy visualized as well as the time required to prepare for and perform otoscopy and the time to the dog's first sign of aversion. The time data were used to assess whether there was a reduction in use of teaching dogs. Data from students exposed to the otoscopy model as part of their prelaboratory training (n = 20) were compared with those that were not exposed to the model (n = 19).

Results

The students found prelaboratory training with the model significantly more helpful than prelaboratory training without the model in all aspects of otoscopy (P < 0.05). Use of the model did not alter otoscopy skill (structures seen or time taken) or decrease dog use.

Conclusions

The students found the model helpful, but the best that can be said is the model did not negatively impact their otoscopy skill acquisition. Although the outcome of the study did not indicate a reduction in teaching dog use, the model has replaced live dog otoscopy in the institute's teaching program for initial canine otoscopy exposure.

Force-based learning curve tracking in fundamental laparoscopic skills training

BACKGROUND

Within minimally invasive surgery (MIS), structural implementation of courses and structured assessment of skills are challenged by availability of trainers, time, and money. We aimed to establish and validate an objective measurement tool for preclinical skills acquisition in a basic laparoscopic at-home training program.

METHODS

A mobile laparoscopic simulator was equipped with a state-of-the-art force, motion, and time tracking system (ForceSense, MediShield B.V., Delft, the Netherlands). These performance parameters respectively representing tissue manipulation and instrument handling were continuously tracked during every trial. Proficiency levels were set by clinical experts for six different training tasks. Resident's acquisition and development of fundamental skills were evaluated by comparing pre- and post-course assessment measurements and OSATS forms. A questionnaire was distributed to determine face and content validity.

RESULTS

Out of 1842 captured attempts by novices, 1594 successful trials were evaluated. A decrease in maximum exerted absolute force was shown in comparison of four training tasks (p ≤ 0.023). Three of the six comparisons also showed lower mean forces during tissue manipulation (p ≤ 0.024). Lower instrument handling outcomes (i.e., time and motion parameters) were observed in five tasks (resp. (p ≤ 0.019) and (p ≤ 0.025)). Simultaneously, all OSATS scores increased (p ≤ 0.028). Proficiency levels for all tasks can be reached in 2 weeks of at home training.

CONCLUSIONS

Monitoring force, motion, and time parameters during training showed to be effective in determining acquisition and development of basic laparoscopic tissue manipulation and instrument handling skills. Therefore, we were able to gain insight into the amount of training needed to reach certain levels of competence. Skills improved after sufficient amount of training at home. Questionnaire outcomes indicated that skills and self-confidence improved and that this training should therefore be part of the regular residency training program.

Interpretation of motion analysis of laparoscopic instruments based on principal component analysis in box trainer settings

BACKGROUND

Motion analysis parameters (MAPs) have been extensively validated for assessment of minimally invasive surgical skills. However, there are discrepancies on how specific MAPs, tasks, and skills match with each other, reflecting that motion analysis cannot be generalized independently of the learning outcomes of a task. Additionally, there is a lack of knowledge on the meaning of motion analysis in terms of surgical skills, making difficult the provision of meaningful, didactic feedback. In this study, new higher significance MAPs (HSMAPs) are proposed, validated, and discussed for the assessment of technical skills in box trainers, based on principal component analysis (PCA).

METHODS

Motion analysis data were collected from 25 volunteers performing three box trainer tasks (peg grasping/PG, pattern cutting/PC, knot suturing/KS) using the EVA tracking system. PCA was applied on 10 MAPs for each task and hand. Principal components were trimmed to those accounting for an explained variance > 80% to define the HSMAPs. Individual contributions of MAPs to HSMAPs were obtained by loading analysis and varimax rotation. Construct validity of the new HSMAPs was carried out at two levels of experience based on number of surgeries.

RESULTS

Three new HSMAPs per hand were defined for PG and PC tasks, and two per hand for KS task. PG presented validity for HSMAPs related to insecurity and economy of space. PC showed validity for HSMAPs related to cutting efficacy, peripheral unawareness, and confidence. Finally, KS presented validity for HSMAPs related with economy of space and knotting security.

CONCLUSIONS

PCA-defined HSMAPs can be used for technical skills' assessment. Construct validation and expert knowledge can be combined to infer how competences are acquired in box trainer tasks. These findings can be exploited to provide residents with meaningful feedback on performance. Future works will compare the new HSMAPs with valid scoring systems such as GOALS.

Novel force-sensing system for minimally invasive surgical instruments

Mastering proper force manipulation in minimally invasive surgery can take many years. Improper force control can lead to necrosis, infection, and scarring. This paper describes a novel system to measure, log, and display external forces at the distal end of minimally invasive surgical instruments in real-time. The system, comprising of a Force- Sensing Sleeve, Bluetooth electronics module, and an Android mobile application. A sensorized 5 mm minimally invasive surgical needle holder was evaluated for bending force accuracy, linearity, and repeatability in six directions. The results showed that the system responded linearly to forces at the tool-tip independent of direction with an RMS error of 0.088 N. Repeatability was affected by system noise potentially arising from temperature drift and thermal noise. Future work will include characterization of communication performance for force feedback in surgical training and assessment.