TissueDB/Simulators/Injection Laryngoplasty Simulator (Lee)

The Injection Laryngoplasty Simulator (Lee) 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 used to locate the injection site. A removable Ecoflex 00-20 silicone insert represents the vocal folds and surrounding endolaryngeal soft tissue and forms the needle target. The trainee palpates the landmarks, passes a needle percutaneously using the thyrohyoid or cricothyroid approach and injects the vocal fold.

Step 1. Obtain the source laryngeal cartilage geometry and the project's modified model files.

Lee et al. developed the framework from publicly available laryngeal anatomy and released the resulting project as an open-source 3D-printing resource.

Step 2. Prepare the framework geometry in Blender 2.79.2.

Add support material between the hyoid bone, thyroid cartilage and cricoid cartilage away from the intended injection sites, and add posterior support to retain the silicone insert.

Step 3. Print the framework.

The baseline source build uses ABS. Lee et al. used a Stratasys Fortus 250mc and reported testing consumer-grade 3D printers and alternative filaments without substantial loss of model quality.

Editorial QA: inspect the completed framework for gross print defects and confirm that the thyroid cartilage, cricoid cartilage and hyoid landmarks remain palpable and spatially distinct. This is a TissueDB buildability check, not a published Lee pass/fail fabrication criterion.

Step 1. Segment the laryngeal airway from an upper-airway CT scan using 3D Slicer 4.10.1.

Threshold the airway lining and crop the model to the laryngeal region.

Step 2. Import the segmented airway into Blender and sculpt it to fit the printed framework.

Step 3. Transfer the model to Autodesk Fusion 360.

Design the four-piece negative mould with the required silicone-injection ports, ventilation ports, bolt holes and alignment features.

Step 4. 3D print the four mould components in ABS.

Step 5. Assemble the mould with standard M3 nuts and bolts, including the source-described 10 mm and 25 mm fasteners.

Step 1. Prepare Smooth-On Ecoflex 00-20 according to the manufacturer's mixing instructions, including degassing as described in the source workflow.

Step 2. Add Silc-Pig pigment PMS 7421C and 488C to produce the pink endolaryngeal colour.

Step 3. Load the silicone into a 60-mL catheter-tip syringe.

Step 4. Connect silicone tubing and inject the mixture into the assembled mould.

Step 5. Allow the silicone to cure overnight.

Timing note: overnight curing is a silicone-processing period only. The source does not report the total time required to prepare digital files, print the framework and mould, cast the silicone and assemble the simulator. Therefore the canonical Build Time remains `-`.

Step 6. Disassemble the mould after curing.

Step 7. Remove the cured silicone endolaryngeal insert.

Editorial QA: inspect the cast for gross defects that would prevent insertion into the framework or injection practice. This is editorial buildability guidance rather than a source-prescribed acceptance test.

Step 1. Place the cured silicone endolaryngeal insert inside the rigid cartilage framework.

Step 2. Position it against the posterior and inter-cartilage supports so that it remains stable during injection practice.

The baseline simulator supports percutaneous injection through the:

• thyrohyoid approach; and
• cricothyroid approach.

A 25-gauge needle is passed percutaneously toward the vocal-fold target.

Injection of air into the vocal-fold region can confirm needle placement.

Evidence distinction: this functional injection behaviour belongs to the Lee 2021 simulator design. It is not a formal TissueDB fabrication-verification protocol.

The rigid ABS framework cannot be pierced and therefore does not support a transthyroid-cartilage approach.

Lee et al. report that thermoplastic polyurethane (TPU) can be substituted for the rigid framework to provide a pierceable variant.

This TPU option is a source-bounded variant and must not rewrite the baseline ABS build.

• Expert reviewers reported that the silicone does not completely reproduce the physical properties of human tissue.
• Silicone does not reproduce the characteristic haptic "pop" associated with penetration of fibromembranous laryngeal structures.
• The source discusses paper, fabric or plastic as possible ways to reproduce that sensation, but those materials are not part of the baseline Version 1 build.
• The ABS framework is not pierceable.
• The 2024 randomized trial demonstrated a significant senior-resident result for tissue respect during the trans-thyrohyoid approach, but junior-resident differences were not significant.
• The 2024 transfer task used an anatomically distinct laryngeal model rather than patients.
• No patient-outcome or clinical-effectiveness claim is supported.

The source reports:

• approximately US$0.96 of filament for one cartilage framework; and
• approximately US$1.89 of Ecoflex 00-20 for one soft-tissue insert.

Together these equal **US$2.85 in source-reported model materials**.

Do not interpret this figure as including:

• the 3D printer;
• computer/software access;
• reusable mould fabrication;
• syringes or tubing;
• fasteners;
• clinical injection equipment; or
• labour.

• Ecoflex 00-20 represents the Vocal Fold and surrounding endolaryngeal soft tissue.
• ABS represents the source baseline thyroid cartilage, cricoid cartilage and hyoid framework.
• PLA and TPU remain alternative/variant printing materials and do not replace the baseline ABS relationships.
• The reusable negative mould is fabrication tooling, not anatomy.
• The 2024 RCT adds validation evidence only; it does not change the Lee 2021 BOM, CAD geometry or material relationships.
• No new anatomy or material relationship is created from the 2024 validation study.