Advancing biomedical R&D
The Principles of Anatomical CAD
Design on anatomical data
3-matic is a software package that allows common Computer Aided Design (CAD) operations on 3D anatomical data. This kind of data is mostly very complex, with organic, freeform shapes (think about a human skull or pelvis) and therefore it is usually represented as a triangulated surface model (STL). 3D anatomical data is generated from medical image data by segmentation in Mimics.
The ability to use CAD operations on anatomical data allows for patient-specific design of implants and devices.
Benefits of patient specific implants:
- perfect fit of the implant onto the patient’s anatomy
- no need for interoperative modifications to the implant
- surgeon has confidence knowing that the implant will fit immediately
- faster surgery means shorter anesthesia time means faster recovery
In the example of the pelvis here; if someone wants to design a patient-specific acetabular cup implant, the typical reflex is to reverse engineer the pelvis in order to get the 3D model in a CAD environment and do the necessary design operations there. However, reverse engineering is a very time-consuming and error-prone process, especially on anatomical data. Moreover, the reverse engineered model will be a simplification of the true geometry, and using this as starting point for the design of a patient-specific implant, might result in an implant that does not fit exactly.
With 3-matic, you can avoid the reverse engineering and perform design operations directly on the anatomical data. This saves time and allows you to work more accurately.
Direct design on anatomical data; flanges of the acetabular cup are designed that fit perfectly onto the pelvic bone of the patient - Click image to enlarge
Anatomical CAD vs traditional CAD
As mentioned in the introduction, 3-matic brings design operations to anatomical data and since this kind of data is mostly represented by triangulated 3D files, 3-matic basically manipulates the triangles, when doing design operations. As such, the way of working is very different from a traditional CAD package and requires a slightly different mindset, although the goal, to design something, remains the same.
The real power of 3-matic is when working with anatomical data and designing patient-specific implants or devices.
Nevertheless, it can be beneficial to get patient data into a CAD environment, e.g. when improving generic implant designs. For this purpose, 3-matic is equipped with an Anatomical Reverse Engineering module that creates solid IGES files from anatomical models. This possibility, together with the ability to import all kinds of CAD data, makes 3-matic perfectly complementary to any CAD package.
Combine design with meshing
The basic principle in 3-matic, the manipulation of triangles, is also very useful when meshing data for finite element analysis (FEA). As such, 3-matic is also a preprocessor. This is a very powerful combination when designing implants that are both perfectly fitting and functional.
Visualization of the triangulated surface of the pelvis and the designed acetabular cup, before and after a remeshing procedure. The remeshing reduces the amount of triangles and optimizes their shape, to make the model suitable for FEA, without compromising the accuracy - click image to enlarge.
The link with Mimics
So 3-matic can import anatomical data from Mimics as a basis for design or meshing, but it is also possible to send 3D models back to Mimics; that way it is possible to validate your patient-specific design on the image data of the patient. Furthermore, in Mimics you can use the gray values from the image data to assign material properties to your meshed anatomical models, allowing more realistic simulations.
To facilitate this workflow, 3-matic has a strong interoperability with Mimics. 3D Objects can be copied (Ctrl-C) from one program and pasted (Ctrl-V) in the other.
In the end, the combination of Mimics and 3-matic achieves a synergistic effect, truly enabling Engineering on Anatomy.
- Use design operations on anatomical data from medical imaging
- Design patient-specific implants or devices
- Combine CAD with 3D patient data
- Directly mesh designs for FEA
- Validate designs on medical image data