TissueDB/Simulators/Humeral Fracture Fixation Simulator

This data-driven, gender-specific simulator uses two 3D printed adult humeral bone models to replicate cortical hardness, cancellous bone porosity, bicortical anatomy, and external contour at right humeral shaft fracture pin drilling sites for modular external fixation.^[1][2] Clear cellophane wrapped around the distracted fragments simulates the soft tissue envelope and permits visual inspection for targeted self-assessment by the learner. The simulator teaches irrigation and debridement, powered and manual drilling, Schanz screw insertion, and rod-to-rod modular frame construction — skills transferable to other limb-saving and life-saving surgeries requiring hardware stabilisation and fixation.^[3]

Step 1. Download the STL files for Adult Male Humeral Bone Model #1 and Model #2 from the 3D files download page.

Step 2. Slice the STL files using Ultimaker Cura or Cura Lulzbot Edition with the following specifications: Fused Filament Fabrication printer, 0.4 mm nozzle, minimum 150 mm build volume Z height, layer height 0.3 mm or less, wall thickness 5.5 mm, infill density 15% with a Tri-Hexagon pattern, bottom layers left at the default value (not 0), no raft, no support, print speed 100% or less, and unexpired white PLA filament.

Step 3. Set the top layers to 0 for both models so the 15% infill that simulates cancellous bone porosity is exposed at each fracture end, revealing the interior anatomy.

Step 4. Print both models. Estimated combined print time is approximately 34 hours (about 17.5 hours each) on a Creality Ender 3, using approximately 294 grams of PLA filament total (150 g + 144 g).

Step 5. Inspect completed models for: smooth sides without layer separation, intact vise attachments, an open interior at the fracture ends exposing the cancellous structure, a 5.5 mm cortical wall, and proper fracture end geometry. See inspection criteria.

Step 1. Cut a roll of clear cellophane in half using a scalpel to make wrapping easier.

Step 2. Cut a wood board to match the width of the table where the simulator will be used. The board must sit flush with the wall and the edge of the table.

Step 3. Assemble and test the powered surgical drill. Insert a properly sized drill bit and confirm forward drilling direction (clockwise rotation when the drill bit tip points away from the operator).

Step 1. Push a table against a wall and position the wood board on the table flush with the wall and table edge.

Step 2. Have an assistant hold both bone models while wrapping clear cellophane around Models #1 and #2 together.

Step 3. Distract the proximal and distal fracture fragments by 2–3 mm while maintaining proper rotational and angular alignment.

Step 4. Position the simulator so each dome base rests on the wood board. The vise attachment of each model should rest against the edge of the wood board.

Step 5. Use the powered drill to drill two holes in the vise attachment of each bone model.

Step 6. Drill corresponding holes into the centre of the side of the wood board to minimise splintering.

Step 7. Insert two nails through the holes of each vise attachment and into the side of the wood board to secure each fragment.

Step 8. Use a hammer to apply mechanical force to fully seat the nails into the drilled holes.

Step 1. Confirm the simulator is oriented to simulate a right humerus in a supine patient. The semi-engraved drilling direction arrows on the base of each model should point lateral-to-medial.

Step 2. Push on each model near the fracture line in lateral-to-medial and anterior-to-posterior directions to verify stability. If movement occurs, insert additional nails.

Step 3. Remove one nail from the vise attachment of the distal fragment (Model #2) to permit fracture displacement during simulation training. This allows the learner to practise fracture reduction and compression using applied force rather than static anatomy.

^[1][2][3]