A Patient-Specific Flexible 3D Printed Orthopedic Model for Training and Teaching of Clubfoot Correction Surgery

Physical models of the human body are important tools in teaching anatomy, training medical professionals, planning complex surgeries, educating patients, and demonstrating medical devices. We present a patient-specific clubfoot model with rigid foot bones suspended independently in a transparent gel matrix that reveals the internal skeletal structure. Compared to cadavers and prosections, our model is a clean and convenient alternative. It offers continuous visual feedback through the transparent skin layer (ideal for training purposes), can be manufactured at demand and reused, and does not require expensive storage and handling facilities. As opposed to other models, which are either purely rigid or flexible, our model is flexible yet with underlying rigid skeletal structure. We believe it has the highest fidelity to human clubfoot in terms of both anatomical structures and material properties. To make this clubfoot model, the knee-to-toe skeleton was first 3D printed using data segmented from a patient's CT data. Then, ballistic gel was melted and cast over the skeleton to create the transparent and flexible skin layer. The flexibility of this clubfoot model permits its recovery to normal foot shape. In addition, the ability of the gel to be repaired with significant recovery of ductility (2.1 +/- 0.4 vs. 3.3 +/- 0.2, p<0.05) enables reuse of the model. Ductility of the finished model can be significantly increased by applying an additional elastic coating (4.3 +/- 0.2 vs. 5.2 +/- 0.2, p<0.05). This clubfoot model opens up the possibility of making other high-fidelity models with complex anatomies and/or material structures.