Posterior Cervical Spine Model #0

Open Source Cervical Surgery Model

First, you print the silicone molds for the skin, spinal cord and the gasket for the lid. I suggest you create many molds for the cord, as it takes very little silicone to fill, and easier to do in big batches. Then you move on to the next step:

How to handle silicone: https://formlabs.com/asia/blog/how-to-make-silicone-molds/ TL;DR: You need a well ventilated area, some vinyl gloves, silicone release spray. Spray the spray to the mold. After mixing the RTV Shore 5 silicone in quantities specified by the producer, you just pour into the mold.  Shake the mold a bit or tap it to the table to release the bubbles. Add the lids to the cord molds. Wait 24 hours.

Then you need to print the dark chamber. I suggest using PETG for all the prints, as it's durable. Silicone molds can be out of PLA.

I suggest fixing the dark chamber to a big plastic tub, or atleast something you can hold on to easily. This way when the resident is using kerrison, whole assembly doesn't come with it. Alternatively you could fix the tub to a table using some belts.

Printing settings for the spine:

---

Printing Specifications Primary Model (Ender-3 S1)

Walls: 3 Infill: 30% adaptive Layer height: 0.2mm Top layers: 4

Alternative Settings (Bambu Lab P1S)

Walls: 2 Infill: 30% adaptive Layer height: 0.2mm Top layers: 3 Top shell thickness 0.6

---

Out of white PETG, you should print the cervical model and remove the tree supports with pliers. 

Then you can put in the spinal cord into it, I found it easier to skewer the cord with a kirschner wire, and pull it through the spinal canal. Then using some forceps (a jeweler's kit works fine) you put the roots into their appropriate foramina.

After that is done, (I suggest you do this in batches again), wet your model with water then using expanding polyurethane spray, place the nozzle into the disc space and fill it up. After you see the foam coming out of the interlaminar line, move on to the next level. In the end, remove the excess foam from the lamina and under the transverse foramen with your gloves. This will make the later cleanup process easier.

After 24 hours of curing, the foam is a solid mass, you can remove it from under the body, so it can slide into the dark chamber and also, remove it from over the lamina, so they are visible. You'll need a snap knife for this or a curved carving knife (like a mushroom knife). Alternatively, you could leave it in place, and ask the resident to dilate/disect the way into the surgical space, which is probably a more advanced way of doing this.

Finally, you place the model into the dark chamber, lock the door with some M3 screws and nuts. And the model is ready. You don't need the silicone gasket at the door if you are not going to work completely underwater, due to budget concerns, the endoscope we used took water into its lens when working completely underwater and just dripped water into the field to prevent PETG from heating up and melting.
 

For CITATION please use: https://asianspinejournal.org/journal/view.php?number=1739
DOI: https://doi.org/10.31616/asj.2025.0050