Currently, orthopaedic surgeons in theAMC (AcademicMedical Centre) in Amsterdam, use an oscillating saw when a bone needs to be sectioned. During these surgeries, which are performed with open surgery, clamps are placed around the bone to protect the surrounding soft tissue from accidental jumping
of the saw blade. These clamps however do not protect the soft tissue properly from the jumping and they damage the soft tissue when being applied. The clamps, the jumping and the open surgery all cause a longer healing time for the patient. Therefore, the orthopaedic surgeons of the AMC desire a novel solution for a bone sectioning device which can be applied minimally invasive and used with as little as possible tissue damage. From an earlier conducted literature review it was decided to use a wire saw, since it is cheap, small and cuts away from the soft tissue. The goal of this project is therefore: Designing a novel instrument or method for minimally invasive sectioning of bone using a wire saw.
To design a new instrument, a structured process needs to be followed, to be able to optimize the instrument from the first steps onward. First a list of requirements was set up from which design challenges have been derived. A brainstorming phase resulted in several solutions to the design challenges. These solutions were combined in a morphological table from which three concepts were derived. These concepts were judged using a Harris profile, from which one concept was chosen to be elaborated further. This concept was
thought out and was based on automated actuation. Based on a procedural assessment this design was considered too complicated, which is why the decision was made to stop using automated actuation. The next iteration was therefore focused on a solution using manual actuation. This design was based on one tube, which guided the two wire saw ends into the soft tissue. After a quick experiment however, it was discovered that the used wire saw had a minimum bending radius,which caused the second iteration to be unable to perform the intended operation. Therefore, a new design has been created using two guiding tubes. This design has been made into a prototype. The prototype has afterwards been used in an experiment in the pathology department. Apart from testing the working principle, the duration of the procedure, the surrounding tissue damage and the quality of cut were tested. In a questionnaire, the workload, the opinion on the shape and size of the surgeon and additional feedback were asked. Also a discussion was held with an expert of a CSD department to check if the prototype is properly cleanable and sterilizable.
The prototype was not able to section the bone completely, it was again hindered by the minimum bending radius of the wire saw. The duration of the procedure was long, but because of the inability to fully section the bone. The duration will be better measurable with a fully sectioning prototype. The assembly of the prototype was fast even though it was the first time the surgeon used it. The surrounding tissue damage was very little, which is very promising. The flatness of the cut was relatively high, which is preferable for the operations this project is focused on. The workload is relatively high compared to literature.
The opinion of the surgeon on the size and shape was low, due to ergonomics and the bulkiness of the prototype. According to the expert of the CSD department, the prototype was properly cleanable and sterilizable except for some minor details. A new initial design based on the findings was made with tubes under an angle of 45 degrees to increase the bending radius of the wire saw during the operation.
The design of a method for sectioning bone with as little soft tissue damage as possible was partially successful. The designed system was not able to fully section the bone, however it was capable of sectioning the majority of it. The soft tissue damage was very low and the flatness of the cut was acceptable.
The design can be improved by either optimizing the used wire saw, or increasing the bending angle of the wire saw during the sectioning procedure.