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New scoliosis implant developed by PDEng trainee

Project PoSTuRE – Patient-specific Scoliosis TREatment – aims to improve the treatment of children younger than 10 with Early Onset Scoliosis (EOS) by developing a new growth guidance system for scoliosis surgery. Project PoSTuRE engaged Floor Gabriels, trainee of the Qualified Medical Engineer PDEng program, to design two critical components.

The most common type of scoliosis surgery corrects the scoliosis by placing two metal rods parallel to the spine and fixate these with screws to the vertebrae. Since these rods don’t grow with the child, repeat surgeries may be necessary as often as every six months. The new growth guidance system, initially developed in a recent PhD thesis, fixates the rods in the middle of the spine with screws and uses high-tensile-strength synthetic wires to pull the spine straight. Because these wires can slide along the rods, vertical growth is possible. Project PoSTuRE, an umbrella project of Maastricht University Medical Center+ (MUMC+), DSM, Eindhoven University of Technology (TU/e), Xilloc and Chemelot InSciTe, is developing this new treatment further.

Designing a personalized solution for a critical step
Project PoSTuRE chose to work with a PDEng trainee because of the complexity of designing the two new components: a spacer to prevent that the rods are pulled to each other by the wires and an accessory personalized to each patient that helps with positioning the screws that go into the vertebrae. Floor: “Vertebrae in scoliosis patients may be severely malformed. That personalized accessory is critical to prevent damage to nerves or blood vessels.”

A PDEng trainee is someone who already has a master’s degree (like a PhD student) and who wants to develop his or her already considerable skills and knowledge to an even higher level. PDEng trainees spend the two years of their PDEng programs taking post-master courses and working on complex real-life design projects. Dr. Chris Arts, Associate Professor of Translational Biomaterials Research at MUMC and Floor’s supervisor: “We very specifically chose a PDEng trainee instead of a PhD student because we wanted someone who could focus on design and development rather than on research. This was the right decision.”

Iterative design to come to the best solution
When developing the two components, Floor first determined the functional criteria. What requirements are there (especially from the orthopedic surgeon and to let it fit in clinical procedures), and what should she keep in mind during the design (also considering al constraints)? After doing (literature and patent) search to determine what was already available, she brainstormed potential new solutions with stakeholders to come up with the first ideas.

Floor: “For the spacer, this first led to a single prototype, which I invited feedback on to create a new version. Several iterations of this process later (including experiments with animals cadavers), I now have a design that meets all functional requirements. For the patient-specific screw guide, we used the same process. The brainstorm session led to three design ideas, and we are now optimizing the best one in close collaboration with the orthopedic surgeon and all the other stakeholders.”

Managing the entire project
Chris: “Floor really took charge of her project. As a result, we made progress in designing both the spacer and the screw guide, which is great.” Floor quickly stepped into the roles required of her: “One thing I realized during this process is the enormous difference between research and product development, especially for healthcare. Working from user needs, formulating those well – it is not just the experimental results that count, but also practical considerations and the opinion of the (clinical) user. To get to a valid product design within two years (in which the design project effectively takes 1 year), you need to be pragmatic, to take charge of the project and the people involved, and keep an eye on the requirements to get to market, such as risk analysis and keeping a design history.”

Valuable results in the time available
Floor’s designs will be tested mechanically in the next six months and optimized further, after which they will be tested in humans, together with the other parts of the growth guidance system. Chris: “What was great is that she also made a lot of progress on the required regulatory documentation for the components. Unfortunately, the project was on the big side for a single PDEng trainee, since Floor also had a fairly high course load (due to the requirements of a PDEng program). This is something we will need to keep in mind when coming up with the next PDEng trainee project, which we will most likely do if budget becomes available.”

And Floor? “Designing is much more my thing than research, this has become clear from my experience in project PoSTuRE. After finishing this design project, I will do another (smaller) project for my PDEng program: I hope to be working on improving or designing the equipment maintenance process in a hospital in Kenya. After finishing this PDEng program, I would like to work in medical product development for developing countries, or to improve project management in medical care in those countries.”