How to create a model of a failing hip replacement for revision hip surgery

[stones]

Hi

I am after some help creating a model of a failing hip replacement for the purposes of surgical planning. I have a CT scan showing the area of interest. I can easily print a model of the bone and hip replacement together. I can print the metal components separately but ideally I would like to print a model that shows the metal in situ in gray and the bone in white. I have been using Osirix to define different thresholds which allows me to specify bone or metal but cant work out how to have one STL file that contains both. I have a dual head 3d printer already. 

My questions is can this be done using Osirix or is there another software package that can do this and how?

Thanks

James

[Terrie S]

Hi James,

If you export each of the separate STL models, you can combine them in Meshlab. Import both models into Meshlab, then go to Filters --> Mesh Layer --> Flatten Visible Layers. This will merge the 2 STL models into one that you can then export.

 

I don't have experience printing with a dual extruder, so I can't help with how to specify the separate color, but I think Cura can handle that.

 

Terrie

[mikefazz]

I typically use KISSlicer which handles multi-material parts(if you use the paid version) slic3r also works.  If the two parts are segmented from the same coordinate system (i.e. line up when loaded on top of each other) then they can be loaded together and each set to its own extruder for printing.  So if one model is the bone even if it overlaps the implant the implant can be given priority and it will print as 'metal' instead of 'bone'.

 

As to segmenting multiple entities in 3DSlicer I use the extension 'FastGrowCut' to segment multiple parts... I don't really bother with thresholding which is too 'global' for my needs.

[stones]

Hi Terrie and Mike

 

Sorry for the delay in responding - i forgot to turn on notifications. I haven't had a chance to check the forum for a few weeks. I much appreciate you taking the time to offer your advice. I will give both methods a go and workout what works best for my needs and post back with my results.

 

Thanks again

 

James

[Dr. Mike]

Agree with Terrie's general strategy. You can export the bone and implant as separate STL files and join them in a mesh-editing software program. I don't use Meshlab, but I know you can do this with MeshMixer and Blender using boolean union. To make things interesting I know if Blender you can assign each object to be a different "material" so when you do the join they will appear differently. If you are planning a multimaterial print this can be useful.

 

In this blog article I talk about printing a spine with orthopedic hardware. I used different materials for the render, but for the 3D print decided to go with only one material. This just shows what you can do though.

 

Dr. Mike