TissueDB/Simulators/Injection Laryngoplasty Simulator (Lee)

The Lee Injection Laryngoplasty Simulator is an open-source, low-cost, 3D-printed laryngeal model for training percutaneous injection laryngoplasty (PIL).^[1] A rigid 3D-printed cartilage framework provides the palpable thyroid-cartilage, cricoid-cartilage and hyoid-bone landmarks for locating the injection site, and a removable silicone insert cast from Ecoflex 00-20 represents the vocal folds and surrounding soft tissue — the needle target. The trainee palpates the landmarks, passes a needle percutaneously through the thyrohyoid or cricothyroid approach, and injects the vocal fold; injected air confirms placement. All 3D-print and mold files are published open-source on Wikifactory.

1. Download the open-source laryngeal cartilage model (University of Dundee / BodyParts3D) and the project's modified files from the Wikifactory repository.
2. Modify the model in Blender 2.79.2: add support material between the hyoid bone, thyroid cartilage and cricoid cartilage (away from the injection sites) and at the posterior aspect to hold the silicone in position.
3. Print the framework in ABS on a 3D printer. The authors used an industrial Stratasys Fortus 250mc and report that consumer-grade printers (e.g. Creality Ender 3, MakerBot Replicator) and other filaments (PLA, thermoplastic polyurethane) gave no substantial loss of quality.

Verification: The printed framework reproduces the thyroid-cartilage, cricoid-cartilage and hyoid-bone landmarks held in their anatomical relationship.

1. Segment the laryngeal airway from a CT scan of the upper airway using 3D Slicer 4.10.1 — threshold the airway lining and crop to the larynx.
2. Import the airway model into Blender and sculpt it to fit the framework, then import it into Autodesk Fusion 360 and design a four-piece negative mold with silicone and ventilation ports, bolt holes and tabs.
3. Print the four-piece mold in ABS.
4. Assemble the mold with standard M3 nuts and bolts (10 mm and 25 mm).
5. Mix Smooth-On Ecoflex 00-20 silicone per the manufacturer's instructions (including degassing) and add Silc-Pig pigment (PMS 7421C and 488C) for a pink hue.
6. Inject the silicone into the assembled mold with a 60-mL catheter-tip syringe and silicone tubing.
7. Cure overnight.
8. Disassemble the mold and remove the cured silicone.

Verification: The cured silicone reproduces the endolaryngeal soft tissue, including the vocal folds.

1. Place the cured silicone into the cartilage framework; the posterior support holds it in position for injection.

Verification: A 25-gauge needle can be passed percutaneously through the thyrohyoid and cricothyroid approaches into the silicone, and injecting air into the vocal fold confirms placement.

• The ABS framework cannot be pierced, so the transthyroid-cartilage approach is not supported. A thermoplastic polyurethane (TPU) framework can be substituted to simulate that approach.
• Expert reviewers judged that the silicone does not fully reproduce the haptics of human tissue, including the "pop" felt when crossing the cricothyroid membrane; the authors note this as an acceptable limitation.