Design and Preliminary Evaluation of a Stiff Steerable Cutter for Arthroscopic Procedures

This article describes a novel and simple shaft actuated tip articulation (SATA) mechanism that allows arthroscopic instruments to articulate while remaining stiff. Since the SATA mechanism requires only independent rotation of two tubes for hinge articulation, cables, gears, or other internal components that are normally found in steerable endoscopic instruments become obsolete. The SATA mechanism was integrated in a new steerable cutter prototype and tested. Early user, mechanical strength and cadaver experiments were performed that indicate that this first prototype withstands an axial and sideways force of 100 N and 20 N, that trained users can (dis)assemble the instrument in less than 1.5 min and that a surgeon is able to reach all important locations on the menisci

The relevance of reducing Veress needle overshooting

Safe insertion of the Veress needle during laparoscopy relies on the surgeons’ technical skills in order to stop needle insertion just in time to prevent overshooting in the underlying organs. To reduce this risk, a wide variety of Veress needle systems were developed with safety mechanisms that limit the insertion speed, insertion depth or decouple the driving force generated by the surgeon’s hand on the needle. The aim of this study is to evaluate current surgeons’ perceptions related to the use of Veress needles and to investigate the relevance of preventing overshooting of Veress needles among members of the European Association of Endoscopic Surgery (EAES). An online survey was distributed by the EAES Executive Office to all active members. The survey consisted of demographic data and 14 questions regarding the use of the Veress needle, the training conducted prior to usage, and the need for any improvement. A total of 365 members residing in 58 different countries responded the survey. Of the responding surgeons, 36% prefer the open method for patients with normal body mass index (BMI), and 22% for patients with high BMI. Of the surgeons using Veress needle, 68% indicated that the reduction of overshoot is beneficial in normal BMI patients, whereas 78% indicated that this is beneficial in high BMI patients. On average, the members using the Veress needle had used it for 1448 (SD 3031) times and felt comfortable on using it after 22,9 (SD 78,9) times. The average years of experience was 17,6 (SD 11,1) and the surgeons think that a maximum overshoot of 9.4 (SD 5.5) mm is acceptable before they can safely use the Veress needle. This survey indicates that despite the risks, Veress needles are still being used by the majority of the laparoscopic surgeons who responded. In addition, the surgeons responded that they were interested in using a Veress needle with an extra safety mechanism if it limits the risk of overshooting into the underlying structures.peer-reviewe

Regarding “Loss of seton in patients with complex anal fistula: a retrospective comparison of conventional knotted loose seton and knot‑free seton” by Verkade et al

Medical Instruments & Bio-Inspired Technolog

Force-based assessment of tissue handling skills

In laparoscopic surgery, special instruments with long and slender shafts are inserted through small incisions in the abdominal wall. A laparoscope is used for a clear vision inside the inflated abdominal cavity while laparoscopic graspers and cutters are used for manipulation of tissue. The use of long instruments makes it difficult to “feel” the force exerted on tissue during manipulation especially when friction factors disturb the force sensation even further. Tissue manipulation plays an important role in surgery and there is relatively little knowledge of forces applied on tissue during surgery. The main objectives of this thesis were to develop force measurement systems to measure the forces during training, to combine motion and force measurements to come to objective assessment of training of basic MIS skills, and finally to develop force feedback systems to improve force application during training. The first part of this thesis focuses on the force exerted by the instrument tips during placement of surgical sutures. In many educational programs in surgery, the suture task is used to test the technical skills of the trainee. We proved that the force exerted on the suture pad can be recorded without modification of the instruments or suture pad if a 3DOF force sensor is placed under the suture pad in a box trainer. We showed that performance parameters can be calculated from recorded force data to expose skills important for safe tissue handling during suturing. A validation study showed that it is possible to classify participants with an accuracy of 84% if only force parameters are used. The second part of this thesis describes a method to reduce the tissue handling force of trainees. By generating a virtual arrow in the laparoscopic image that represents the size and direction of the exerted force during suturing in real time, we found that training with well explained visual feedback can help trainees to minimize the interaction force during needle insertion in a box trainer. For training of wound suturing outside the box trainer, we found that colours, representing the exerted force on the tissue, can help trainees to balance forces between the two tensioned threads during knot tying and to improve the quality of the knot. In another study we showed that it is possible to inform the surgeon about the pulling force during surgery if a small and lightweight sensor is used that can be easily attached to the tensioned thread. The third part of this thesis we integrated the TrEndo and a force platform into ForMoST, a box trainer that measures both tissue handling force as instrument motion. For this box trainer we developed and validated two new bimanual training tasks for training of tissue handling. The validation study performed with novices, intermediates and experts indicated that force parameters are not strongly correlated to motion parameters and that force and motion parameters have similar discriminative power in both tasks. A study performed with novices that received visual force feedback or visual time feedback during training indicated that visual force feedback during training reduces the tissue manipulation force significantly even when a post task is performed that is different from the training task. We showed that training with visual force feedback improves tissue handling skills with no negative effect on task time and instrument motion and that training with visual time feedback improves instrument motion and task time, but does not improve tissue manipulation skills. This thesis contributes to the field of training of surgical skills in multiple ways. Mechanical force sensors were developed that can be used for training of tissue handling, to find force thresholds for traction on tissues or for safety monitoring during suturing of incisions. It is shown that force parameters that reflect tissue handling or suture tension, can now be used to inform surgeons about the risk of tissue damage while training laparoscopic skills or suturing tissues.BioMechanical EngineeringMechanical, Maritime and Materials Engineerin

Duurzame robotchirurgie

Chirurgische robotsystemen winnen aanzienlijk aan populariteit in de medische wereld vanwege hun voordelen op het gebied van precisie, comfort en behendigheid voor de chirurg, wat resulteert in een verbeterd chirurgisch resultaat. Deze voordelen gelden voor ziekenhuizen over de hele wereld, maar zijn niet overal even toegankelijk. Complexe systemen vereisen meer onderhoud, meer training voor gebruik, een aanzienlijke hoeveelheid ruimte, een grote financiële investering en ingewikkelde reinigings- en sterilisatieprocessen. Hierdoor is het integreren van deze robotsystemen toch vaak een uitdaging door de beperkte financiën en infrastructuur in kleinere ziekenhuizen. Dergelijke barricades leiden er vaak toe dat de technologie onbereikbaar wordt in omgevingen die het soms het hardste nodig hebben. De ontwikkeling van goedkope robotsystemen lijkt daarom de sleutel voor minder bedeelde ziekenhuizen om toch toegang te krijgen tot de voordelen die robotchirurgie kent

Surgical Instrument

The present invention relates to a surgical instrument for minimall-invasive surgery, comprising a handle, a shaft and an actuating part, characterised by a gastight cover surrounding the shaft, wherein the cover is provided with a coupler that has a feed- through opening with a loskable seal, through which feed- through opening, after the seal is unlocked, the shaft with the actuating part can reach.Mechanical, Maritime and Materials Engineerin

Improving training of laparoscopic tissue manipulation skills using various visual force feedback types

Background Visual force feedback allows trainees to learn laparoscopic tissue manipulation skills. The aim of this experimental study was to find the most efficient visual force feedback method to acquire these skills. Retention and transfer validity to an untrained task were assessed. Methods Medical students without prior experience in laparoscopy were randomized in three groups: Constant Force Feedback (CFF) (N = 17), Bandwidth Force Feedback (BFF) (N = 16) and Fade-in Force Feedback (N = 18). All participants performed a pretest, training, post-test and follow-up test. The study involved two dissimilar tissue manipulation tasks, one for training and one to assess transferability. Participants performed six trials of the training task. A force platform was used to record several force parameters. Results A paired-sample t test showed overall lower force parameter outcomes in the post-test compared to the pretest (p < .001). A week later, the force parameter outcomes were still significantly lower than found in the pretest (p < .005). Participants also performed the transfer task in the post-test (p < .02) and follow-up (p < .05) test with lower force parameter outcomes compared to the pretest. A one-way MANOVA indicated that in the post-test the CFF group applied 50 % less Mean Absolute Nonzero Force (p = .005) than the BFF group. Conclusion All visual force feedback methods showed to be effective in decreasing tissue manipulation force as no major differences were found between groups in the post and follow-up trials. The BFF method is preferred for it respects individual progress and minimizes distraction.Medical Instruments & Bio-Inspired Technolog

Duurzame robotchirurgie

Chirurgische robotsystemen winnen aanzienlijk aan populariteit in de medische wereld vanwege hun voordelen op het gebied van precisie, comfort en behendigheid voor de chirurg, wat resulteert in een verbeterd chirurgisch resultaat. Deze voordelen gelden voor ziekenhuizen over de hele wereld, maar zijn niet overal even toegankelijk. Complexe systemen vereisen meer onderhoud, meer training voor gebruik, een aanzienlijke hoeveelheid ruimte, een grote financiële investering en ingewikkelde reinigings- en sterilisatieprocessen. Hierdoor is het integreren van deze robotsystemen toch vaak een uitdaging door de beperkte financiën en infrastructuur in kleinere ziekenhuizen. Dergelijke barricades leiden er vaak toe dat de technologie onbereikbaar wordt in omgevingen die het soms het hardste nodig hebben. De ontwikkeling van goedkope robotsystemen lijkt daarom de sleutel voor minder bedeelde ziekenhuizen om toch toegang te krijgen tot de voordelen die robotchirurgie kent.Medical Instruments & Bio-Inspired Technolog

Navigation forces during wrist arthroscopy: assessment of expert levels

To facilitate effective and efficient training in skills laboratory, objective metrics can be used. Forces exerted on the tissues can be a measure of safe tissue manipulation. To provide feedback during training, expert threshold levels need to be determined. The purpose of this study was to define the magnitude and the direction of navigation forces used during arthroscopic inspection of the wrist. We developed a set-up to mount a cadaver wrist to a 3D force platform that allowed measurement of the forces exerted on the wrist. Six experts in wrist arthroscopy performed two tasks: (1) Introduction of the camera and visualization of the hook. (2) Navigation through the wrist with visualization of five anatomic structures. The magnitude (Fabs) and direction of force were recorded, with the direction defined as α being the angle in the vertical plane and β being the angle in the horizontal plane. The 10th-90th percentile of the data were used to set threshold levels for training. The results show distinct force patterns for each of the anatomic landmarks. Median Fabs of the navigation task is 3.8 N (1.8-7.3), α is 3.60 (-54-44) and β is 260 (0-72). Unique expert data on navigation forces during wrist arthroscopy were determined. The defined maximum allowable navigation force of 7.3 N (90th percentile) can be used in providing feedback on performance during skills training. The clinical value is that this study contributes to objective assessment of skills level