# OsteotomyCuts: a new extension for multi-segment osteotomy planning (orthognathic and craniofacial)

**URL:** <https://discourse.slicer.org/t/osteotomycuts-a-new-extension-for-multi-segment-osteotomy-planning-orthognathic-and-craniofacial/48329>\
**Category:** Announcements\
**Created:** [September 29, 2026, 2:23am UTC](https://discourse.slicer.org/t/osteotomycuts-a-new-extension-for-multi-segment-osteotomy-planning-orthognathic-and-craniofacial/48329 "2026-09-29T02:23:21Z")\
**Posts on this page:** 8\
**Page:** 1

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**Author:** ![manjula](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/manjula/32/80981_2.png) [@manjula](https://discourse.slicer.org/u/manjula)\
**Post date:** [September 29, 2026, 2:23am UTC](https://discourse.slicer.org/t/osteotomycuts-a-new-extension-for-multi-segment-osteotomy-planning-orthognathic-and-craniofacial/48329/1 "2026-09-29T02:23:21Z")

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Hi everyone,

I’d like to share a small extension I created with CluadeCode: **OsteotomyCuts**.

For years my biggest frustration with virtual planning in Slicer was cutting. Cuts were hard to predict, and complex osteotomies (a stepped Le Fort I, a BSSO, a chevron genioplasty) were difficult or impossible to make cleanly. So I tried to solve it for myself.

I’m not a software developer. I built this with **Claude Code (Pro)**, directing and testing every step myself, over about two days alongside clinical work. The actual development time with Claude Code was a few hours. Everything, from the code, tests and documentation to the logo, was produced with Claude Code or Claude under my direction and checked by me.

**What it does (Phase 1)**

- Draw an **osteotomy line** of any shape on the bone and set the **saw direction**. The bone is divided into **closed, printable bone segments**.
- **Saw blade thickness** , **cut depth** and **cut reach** , so a cut stops where you want it.
- **Several osteotomy lines in one step** (e.g. the horizontal and pterygomaxillary cuts of a Le Fort I). Le Fort I, II and III, BSSO, genioplasty and segmental cuts can all be built this way.
- **Symmetrical cuts:** mirror an osteotomy to the other side across a midline plane, or make a line symmetric.
- **Structures to protect:** add the nerve canal or tooth roots with a safe distance; the preview turns green, amber or red, and you’re warned before cutting.
- **Model quality checks** , and an optional **“Create solid bone model”**. You don’t normally need it, but it helps when a segmentation has holes or internal surfaces and a cut doesn’t behave.

The multi-segment cuts, symmetrical cuts and safety-distance check are features I haven’t found in the planning tools I’ve used, so I hope they’re useful to others.

It’s research and planning software, **not a medical device**. There’s a clear disclaimer and a first-use terms dialog. It’s free and open source under GPL-3.0-or-later.

**What’s next**

This is Phase 1. Next I plan to add **guided templates** (Le Fort I, BSSO, genioplasty, segmental), followed by segment repositioning and other planning tools. The longer-term aim is a **free, complete orthognathic planning workflow in Slicer** , validated against commercial software, for colleagues who can’t afford high licence fees.

**Links**

- Repository: [GitHub - cmfsx/SlicerOsteotomyCuts: 3D Slicer extension for multi-segment osteotomy planning in orthognathic and craniofacial surgery · GitHub](https://github.com/cmfsx/SlicerOsteotomyCuts)
- DOI: [Zenodo DOI]
- Quick Video: [[link or video](https://youtu.be/yZYDwWlut5I)]

 ![2](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/4/b/4bf05e500ba794e800f28d2096a46577ebef8bb8.jpeg)

 ![1](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/2/9/29c3b6484ef67de343a326731c05315c68340baa.jpeg)

I’d be very grateful if you’d try it and tell me what’s wrong: bugs, clinical logic, the interface, anything. Criticism is welcome. I’ve submitted it to the Extensions Index [[PR link]](https://github.com/Slicer/ExtensionsIndex/pull/2403); any help from the core developers in getting it there, or advice on doing things the Slicer way, would be much appreciated.

Thank you to the Slicer community for such a remarkable platform.

Manjula Herath

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**Author:** ![Bhawana](https://avatars.discourse-cdn.com/v4/letter/b/35a633/32.png) [@Bhawana](https://discourse.slicer.org/u/Bhawana)\
**Post date:** [September 29, 2026, 2:44am UTC](https://discourse.slicer.org/t/osteotomycuts-a-new-extension-for-multi-segment-osteotomy-planning-orthognathic-and-craniofacial/48329/2 "2026-09-29T02:44:08Z")

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**Author:** ![CarlosJWinkler](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/carlosjwinkler/32/80398_2.png) [@CarlosJWinkler](https://discourse.slicer.org/u/CarlosJWinkler)\
**Post date:** [September 29, 2026, 4:07pm UTC](https://discourse.slicer.org/t/osteotomycuts-a-new-extension-for-multi-segment-osteotomy-planning-orthognathic-and-craniofacial/48329/3 "2026-09-29T16:07:13Z")

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Hi Dear Herath.

Thank you very much by share this tool,  
I am ready to offer my support on testing the new tools you shared.

Best regards.  
Carlos J. Winkler  
55 11 98553-2450

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**Author:** ![Pedro\_Zaju](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/pedro_zaju/32/78296_2.png) [@Pedro\_Zaju](https://discourse.slicer.org/u/Pedro_Zaju)\
**Post date:** [September 29, 2026, 4:17pm UTC](https://discourse.slicer.org/t/osteotomycuts-a-new-extension-for-multi-segment-osteotomy-planning-orthognathic-and-craniofacial/48329/4 "2026-09-29T16:17:12Z")

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Thanks for sharing this, Manjula!

This looks really interesting. The video does a great job showing how it works, and I liked the music too. Are you aware of any existing work in Slicer on generating patient-specific cutting guides from planned osteotomies? If not, that could be an interesting project to take on.

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**Author:** ![dzenanz](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/dzenanz/32/1992_2.png) [@dzenanz](https://discourse.slicer.org/u/dzenanz)\
**Post date:** [September 29, 2026, 4:41pm UTC](https://discourse.slicer.org/t/osteotomycuts-a-new-extension-for-multi-segment-osteotomy-planning-orthognathic-and-craniofacial/48329/5 "2026-09-29T16:41:55Z")

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@Sam_Horvath might know more about status and relevant capabilities of [iCSPlan](https://www.kitware.com/kitware-fuels-pediatric-surgery-planning-project-with-1-5-million-award/).

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**Author:** ![manjula](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/manjula/32/80981_2.png) [@manjula](https://discourse.slicer.org/u/manjula)\
**Post date:** [September 29, 2026, 5:02pm UTC](https://discourse.slicer.org/t/osteotomycuts-a-new-extension-for-multi-segment-osteotomy-planning-orthognathic-and-craniofacial/48329/6 "2026-09-29T17:02:25Z")

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Hi Pedro,

Thanks for the reply. Yes I will be doing PSI guide generation as the next step. Right now it can be done with 3D Slicer using segment editor or markups to model. Right now i am working on the templates for different osteotomies. Once it is complete i will move on to the guide generations and other.

[https://youtu.be/TUbL08TV5C8](https://www.youtube.com/watch?v=TUbL08TV5C8)

Thanks

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**Author:** ![manjula](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/manjula/32/80981_2.png) [@manjula](https://discourse.slicer.org/u/manjula)\
**Post date:** [September 29, 2026, 5:03pm UTC](https://discourse.slicer.org/t/osteotomycuts-a-new-extension-for-multi-segment-osteotomy-planning-orthognathic-and-craniofacial/48329/7 "2026-09-29T17:03:37Z")

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Thanks please let me know

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**Author:** ![kuldeepvish5](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/kuldeepvish5/32/18832_2.png) [@kuldeepvish5](https://discourse.slicer.org/u/kuldeepvish5)\
**Post date:** [September 30, 2026, 4:21am UTC](https://discourse.slicer.org/t/osteotomycuts-a-new-extension-for-multi-segment-osteotomy-planning-orthognathic-and-craniofacial/48329/8 "2026-09-30T04:21:20Z")

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Thanks for developing this extension…will definitely try it.