University of Twente Student Theses


Design a novel device to locate and secure a metacarpophalengeal implant within the joint capsule.

Buter, E.M. (2022) Design a novel device to locate and secure a metacarpophalengeal implant within the joint capsule.

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Abstract:Background: Osteoarthritis is the most prevalent musculoskeletal disease and results in pain, stiffness and decreased mobility of the joints. Surgery is the last treatment options when the disease is progressed. For the metacarpophalangeal joint in the thumb (MCP1) the two surgical options are joint fusion or joint replacement. These options are invasive and do not restore the original range of motion of the joint. To overcome these problems, an implant, the APRICOT, was designed for the MCP1 joint. The implant can be placed in between the joint surfaces, where it enables the preservation of healthy bone and tissue and will not require invasive surgery. However, the implant cannot be placed with currently available instruments due to the limited space inside the MCP1 joint. Therefore a novel device was designed to locate and secure the metacarpophalangeal implant within the joint capsule. Method: First the problem was analysed and the required functions and requirements were listed. After that, three synthesis phases were performed. During these three phases, solutions for the required functions were designed and combined into concepts. Through the phases, concepts are designed, evaluated and improved. Phase I ends with the three best concepts, which were improved in phase II. In phase II, these three concepts were improved and tested in 3D printed bones and cadaver trials. With the results of these tests and the evaluation of the APRICOT design group and the surgeon, the final concept was chosen and improved in phase III. Design: The final concept are tweezers existing of two parts that can easily slide into each other. The bottom part can grab the implant with the tips and the top part can be pressed to the bottom part and grab the reformed implant. After that the tweezers can drag the implant inside of the joint. If needed, the two parts of the tweezers can be retracted out of the joint, one by one. After retracting the tweezers, the implant needs to be reformed to its original shape. The reformation is performed with an additional instrument shaped like a hook. Discussion and conclusion: The developed instrument can successfully insert the implant inside of the joint and the requirements are met. However, the implant and tweezers still need to be adjusted to each other to optimise the performance. The material, production process and sterilisation method depend on whether the instrument is reusable or disposable. Looking at an overview of the costs, feasibility of the production process and stiffness of the instrument, the recommendation is to use disposable stainless steel tweezers. Secondly, the final reformation of the implant with the hook requires further research. The hook already shows promising results in 3D printed bones, but a cadaver trial is needed to confirm that there is enough space and that the hook will operate as expected. Concluding, we successfully designed an instrument for placement of the APRICOT implant and tested the instrument in cadaver studies.
Item Type:Essay (Master)
Faculty:ET: Engineering Technology
Subject:44 medicine, 52 mechanical engineering
Programme:Biomedical Engineering MSc (66226)
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