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.

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 experience stiffness perception during laparoscopic surgeries. Better understanding of the perception of tissue stiffness could contribute to the development of better laparoscopic instruments. A stiffness ranking task has been performed with 16 participants, to study the influence of force transmission ratio, contact area and grasping strategy on the haptic perception of variable tissue stiffness. Using a newly developed set of laparoscopic grasper handles varying in the chosen independent variables, being the force transmission ratio and contact area, the participants performed multiple grasps with each grasper handle on a randomized order of tissue samples with three different stiffness levels and ranked them according to the perceived level of stiffness. Force measurements were done during the task and a survey was conducted afterwards. The results indicate that force transmission ratio and contact area do not influence the haptic perception of variable tissue stiffness. In terms of grasping strategy, a lower force exertion is shown to be desirable for perceiving the variable tissue stiffness, while the amount of grasps per tissue sample have not shown to influence the perception. Future studies with larger sample sizes might indicate a difference between high and low force transmission ratios. It is concluded that future designs of laparoscopic grasper handles might not be restricted in terms of force transmission ratio and contact area requirements when a greater haptic perception is aimed at. More haptic perception of variable tissue stiffness is gained in the surgical domain of applying the appropriate grasping strategies.

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. In this study, a new force limiting device is designed according to the BME­CI approach and tested. The new design uses a standard laparoscopic grasper as a basis and limits the pinch force with a compliant element that locks in place based on the force applied. The device underwent mechanical evaluation that looked at the force transmission of the entire force limiting mechanism, stiffness and input/output relationship of the compliant elements. The mechanical evaluation showed that the device is able to successfully limit the pinch force exerted and that a symmetrical compliant element offers better force locking and sensing characteristics compared to a non­symmetrical one. A small simulated clinical trial with 10 participants was done. The results showed that no significant difference in task time (p=0.548), slippages, meant issue handling force (p=0.462) and maximum tissue handling force (p=0.602) between the two lowered force conditions could be found. Improvements could be made regarding the sensing of forces and the exact locking characteristics

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.