Bone Biopsy Simulation

Dr. Nicholson Chadwick, The Wond'ry

Summer 2022

Bone biopsies are a difficult procedure to perform, requiring medical professionals to drill into some of the hardest bones in the human body. To be properly performed, Doctors must stop drilling with precision down to the millimeter. Obviously, this requires much training and good muscle memory to prevent taking multiple core samples unnecessarily. Unfortunately, the standard method of training is just to observe a practitioner and participate in live procedures.

To assist in training, we designed and fabricated a training tool for medical workers to learn how to safely and effectively perform a bone biopsy. This is better than alternatives as it is quite realistic without requiring human tissue, preventing negative effects caused by inexperienced trainees performing live operations.

There were a few main considerations for the design process. First, we wanted to include a variably tapered width on the medullary and cortical bones to simulate a wider range of bone compositions. Next, we wanted to ensure the soft tissue layer was soft enough to be realistic, but durable enough to withstand many punctures. The last major consideration was finding the perfect hardnesses for the two different bone layers. Once we came to a conclusion on these issues, it was time for manufacturing.

I designed the models for the 3 separate layers of tissue in CAD. The cortical bone tapers from a narrow diameter to a larger one in order to simulate different bone compositions while the medullary bone and soft tissue layers both keep consistent diameters to allow for them to be interchanged. This allows the bone to be swapped out as it is regularly drilled into as well as expandability in the future as we pursue potentially more complex models. I then designed and 3D printed the positive molds for each part. Using thermoform plastic (as we couldn’t print each mold in one piece) I vacuum formed the 3 final molds for each piece. I poured different materials into their respective molds in order to properly simulate the visual and tactile feedback expected from each layer during the drilling process. </p>

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