Construction of a Simple and Extremely Low-Cost 3D-Printed Ultrasound Model for Training in the Pericapsular-Nerve Group (PENG) Block Technique.

3D printing has multiple applications in the practice of medicine, including but not limited to the construction of 3D models to facilitate training in ultrasound-guided regional anaesthesia. Such models are typically far less expensive than commercially developed "phantom" trainers, making them particularly attractive in scenarios where budget constraints may impact regional anaesthesia training opportunities. The PEricapsular Nerve Group (PENG) block is a relatively recently described regional anaesthesia technique that is particularly useful in providing post-operative analgesia to patients undergoing hip replacement. To date, there are very few commercially available phantom models that permit the practice of the PENG block ex vivo, and those that do exist are considerably costly to purchase. This report describes the process of using readily accessible home 3D printing technology to create an extremely low-cost, simple-to-assemble phantom of the hip region, suitable for practicing the needling techniques necessary to carry out the PENG block. It may be of particular interest to regional anaesthesia training centres where funding issues present an obstacle to purchasing commercial models. The report demonstrates construction feasibility and preliminary sonographic usability of such a phantom, without formal evaluation of trainee learning, expert-rated fidelity, and comparative educational value. Free, open-source software and 3D models were used to prepare an appropriate pelvic model for printing. Stereolithography (SLA) 3D printing technology was used to produce a resin-based model of the pelvis, with gelatine utilised to create a tissue layer encompassing the model. A sonographic representation of the psoas tendon (a notable landmark in the block) was created, utilising pasta strands encompassed in nitrile and embedded in the gelatine at the expected location along the pelvic brim. The ultrasound characteristics of this phantom were reasonable, and the phantom permitted multiple needling attempts. The total cost for the production of this phantom was slightly over 12 euros (excluding initial 3D printer purchase and post-processing materials), and the total preparation time was 20 hours, including print time, print pre- and post-processing time, and gelatine setting times. This 3D phantom was produced using home 3D printing technology and affordable, readily available materials, for an exceptionally low cost and relatively fast production time. The limitations of the phantom include a short shelf life if not frozen, simplified anatomy, and relatively low ultrasonographic soft-tissue fidelity. Additional strategies for improving these aspects are discussed and could be implemented if desired.