Objective: Grasping force control is crucial for safe laparoscopic surgery. However, force feedback is limited as haptic information on grasping strength and tissue stiffness is mostly lost due to internal instrument backlash and friction. This increases tissue trauma risk as excessive grasping forces can lead to (postoperative) complications. This study aims to develop a grasping force feedback providing add-on for a laparoscopic grasper and to validate its impact on skills acquisition in basic laparoscopic skills training. Method: The ShaftFlex, a shaft-based grasping force measurement system providing feedback was designed as an add-on for standard reusable instruments. It consists of a compliant element deflecting proportionally to the applied grasping force, and a Hall sensor measuring that deflection. Influence on skills acquisition was evaluated in a comparative study where novices were divided into a Feedback and No feedback group, performing five training trials of a silicon torus transfer boxtrainer task. Afterwards, both groups performed a post-training task without feedback. Grasping force, time to completion and number of errors were measured. Results: There was a significant difference in mean grasping force between groups for all training trials and the post-training trial. In the Feedback group, there was no significant increase in grasping force when feedback was removed. Conclusions: The ShaftFlex working principle provided a feasible, sustainable method to measure grasping forces exerted by a laparoscopic grasper, enabling immediate haptic feedback. It potentially enhances objective skill assessment, providing feedback on training performance. In a clinical context, the ShaftFlex might be useful in surgery where delicate tissue is grasped.

Background: The Veress Needle (VN) is commonly used in establishing pneumoperitoneum in laparoscopic surgery. However, severe vascular and/or visceral complications can occur due to overshoot at the insertion of the VN in the abdominal cavity. In order to investigate whether the new VeressPLUS needle (VN+) could improve safety, the learning curve of this needle was compared to that of a conventional VN, under standardized conditions. Methods: In total, 26 residents and med students, without prior Veress needle experience, were recruited and randomly assigned to VN or the VN+ group. A learning curve plateau phase recognition model was developed and used to determine the learning curve of the participants who used either the VN or the VN+ needle on two Thiel-embalmed human cadavers. Insertion of the needles was done in a systematic way in the upper abdomen and insertion depth was measured under direct laparoscopic vision. At the end of the learning curve, the number of participants that reached a safe insertion depth between 5 and 15 mm was compared. Results: On average, it took the VN group 8 trials to reach and establish the plateau phase of the learning curve. The VN+ group showed no learning curve at all. At the 8th trial, a significant difference (p < 0.002) in average insertion depth was found in favor of the VN+ (mean: 5.4 mm SD 1.4) compared to the VN (mean: 12.7 mm SD 6). In the VN group and VN+ group, 46% versus 8% exceeded the safe insertion depth of 10 mm at the end of the learning curve. Conclusion: This study indicates that for novices, there is no learning curve for the VN+, when compared to VN. Moreover, in all cases, the insertion depths were significantly reduced (with more than 50%) while using the VN+ when compared to the VN.