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The design, production and validation of a force limiting mechanism in a laparoscopic instrument

Master thesis (2023) - E.C. Schlösser, J.W.A. Klok, T. Horeman

Laparoscopic surgery uses small incisions and a camera for abdominal or pelvic operations, with benefits such as shorter recovery time and hospital stay. However, reduced surgeon hand-eye coordination and feedback can lead to excessive applied force and poten ...

Laparoscopic surgery uses small incisions and a camera for abdominal or pelvic operations, with benefits such as shorter recovery time and hospital stay. However, reduced surgeon hand-eye coordination and feedback can lead to excessive applied force and potential tissue damage. Haptic and visual feedback systems have been developed for laparoscopic surgery, and their benefits for various laparoscopic tasks have been demonstrated. Although force feedback systems have been extensively studied, there is a dearth of research on force limiting mechanisms in laparoscopic surgery. Nonetheless, incorporating force limiting mechanisms could help prevent complications caused by excessive applied force by the user. This paper presents the design, production and validation of a force limiting mechanism in a laparoscopic instrument, to prevent tissue damage due to excessive applied force by the surgeon. A design method was conducted, which comprised a functional analysis and a design process. Subsequently, a force limiting mechanism was designed and manufactured using various techniques. To validate the mechanical performance, the force in the forceps Fpinch and the force in the rod Frod of the laparoscopic instrument were measured. This was carried out under three conditions with the force limiting mechanism set at 10 N, 20 N, and 40 N for Fpinch. To validate pre-clinical performance, twenty novices performed a crossover study. Participants performed a basic laparoscopic task by grasping a Floral foam object under two conditions: with and without the force limiting mechanism. The relative depth and the slippages of the Floral foam object was computed after each trial. The mechanical validation results showed that for the instrument with the force limiting mechanism, Fpinch remained constant at 0.5 N and 2.0 N, while Frod increased. The pre-clinical validation revealed a significant difference in relative depth between the two instruments. The laparoscopic instrument with the force limiting mechanism was superior compared to the laparoscopic instrument without the force limiting mechanism (p<0.001), as less force was transferred by the force limiting mechanism. Additionally, no difference was found between the two instruments in slippages (p=0.068). It can be concluded that a force limiting mechanism in a laparoscopic instrument has been successfully designed and validated and can prevent tissue damage by blocking the excessive applied force by the surgeon. However, further improvement is required to overcome limitations in the design. Moreover, the design has to be tested in various (pre-)clinical settings in order to improve the validity and reliability of the design. Additionally, implementing the force limiting mechanism in robotic surgery should also be considered.

Innovative design and evaluation of a reusable drill guide for distal cement plug removal in total hip arthroplasty revision

Master thesis (2023) - J. Groenewegen, J.W.A. Klok, T. Horeman, M. van der Elst

Distal cement plug removal in total hip arthroplasty revision is a time-consuming and technically challenging procedure. There is a risk of perforating the femur while drilling in the cement plug. This risk increases when the orientation of the prosthesis tip is excentric. The ai ...

Distal cement plug removal in total hip arthroplasty revision is a time-consuming and technically challenging procedure. There is a risk of perforating the femur while drilling in the cement plug. This risk increases when the orientation of the prosthesis tip is excentric. The aim of this study was to design a reusable drill guide that facilitates centric drilling in the cement plug and to evaluate this design. The extremity of the drill guide contains two centralizers. Activation of the centralizers results in the centralization of the drill guide in the femur. A set of requirements was defined for the drill guide. To check if the drill guide meets these requirements, different tests were performed. The centralizers were tested in a fatigue test and a radial force test. The usability and functionality of the drill guide were tested in a simulation of the cement plug removal procedure performed by an orthopaedic surgeon. In this simulation was a cement plug in a bone sample drilled in three different conditions. The first condition was without the drill guide. The second condition was with the drill guide by which the handle was kept pressed during the drilling. The third condition was with the drill guide but the handle was released after activation. Furthermore, the disassembly and assembly of the drill guide were tested by five inexperienced test subjects, and the cleaning and sterilization of the drill guide were discussed with experts. This study's results show that the drill guide prototype meets the requirements. The centralizers could be activated ten times without breaking and will not apply a force on the bone that exceeds the yield stress of cortical bone. The absolute deviation of the position of the drilled hole from the centre of the cement plug was significantly lower in the tests with the drill guide compared to the tests without the drill guide. The same test showed that the generated temperature by the drill guide will not cause bone necrosis. Furthermore, the (dis)assembly of the drill guide was performed in less than 110 s. However, the drill guide would benefit from some design adjustments and further testing, such as testing the durability after multiple sterilization cycles. When this is included in the design, the drill guide could be a valuable addition to the standard tools in THA revision.

Design and validation of a force feedback providing add-on for a laparoscopic grasper

Master thesis (2023) - Y.E. Smits, T. Horeman, J.W.A. Klok

The influence of laparoscopic handle design parameters and grasping strategy on the haptic perception of variable tissue stiffness

Master thesis (2022) - L. Lesmana Hardjo, J.W.A. Klok, T. Horeman, J.J. van den Dobbelsteen

Stiffness perception in laparoscopic surgery has an important role in achieving appropriate tissue manipulation. The need for haptic feedback to perceive tissue stiffness and the reduce in haptic feedback when using laparoscopic instruments suggest an inability to sufficiently ex ...

An Adjustable Force Limiting And Sensing Mechanism For Laparoscopic Forceps Graspers

Master thesis (2021) - R.S.J. Miedema, J.W.A. Klok, T. Horeman

In laparoscopic surgery, surgeons may cause damage to internal tissues due excessive pinch forces while using laparoscopic forceps graspers. Low mechanical efficiency, poor haptic feedback and visual perception errors causes surgeons to be unable to correctly asses pinch forces. ...

Designing a Tourniquet for a Fully-Automated Venipuncture Device

Master thesis (2020) - T.W.J. de Boer, J. Dankelman, N. Tolou, J.W.A. Klok

Phlebotomy - the drawing of blood - is essential for medical diagnostics, but there are problems with inconsistent sample quality, complications and high operational costs. Automation of the phlebotomy process may solve these problems; however not all steps of the phlebotomy proc ...

Phlebotomy - the drawing of blood - is essential for medical diagnostics, but there are problems with inconsistent sample quality, complications and high operational costs. Automation of the phlebotomy process may solve these problems; however not all steps of the phlebotomy process are currently automated. Automatic vein detection and needle puncturing have already been developed, but the tourniquet, a device used to cease the flow of blood, still needs to be automated. This study aims to design and evaluate an automated tourniquet for a fully-automated venipuncture device. In this study, two concepts were explored. The elastic tourniquet uses a strap tightened by an electric motor. The pneumatic tourniquet uses an air filled bladder, which is inflated to a standardized pressure. Both prototypes were realised and verified according to the system requirements. After verification a validation was conducted with seventeen participants, to determine usability and test user requirements. The participants used both prototypes and scored them on ease of use, comfort and sense of safety. Both prototypes did not meet three out of nineteen requirements during verification, but the shortcomings were deemed only minor. Both prototypes were considered easy to use, reasonably comfortable and instilled subjects with a high sense of safety. The pneumatic prototype scored slightly higher on comfort and safety. Users were able to apply the elastic tourniquet significantly faster and less mechanical noise was produced during operation. This study shows that it may be possible to implement automated tourniquets in fully-automated venipuncture devices in the near future. I conclude that the elastic prototype is best suited for automated phlebotomy. The shortcomings can be solved with little difficulty, whilst the design is less complex and more scalable. For this, I recommend performing clinical device testing to validate the performance of this novel tourniquet concept.

Jan-Willem Klok

Authored

Design and In Vitro Validation of an Orthopaedic Drill Guide for Femoral Stem Revision in Total Hip Arthroplasty

Design And Evaluation Of A Balanced Compliant Laparoscopic Grasper