The Embodi3D website offers a large and ever-growing library of 3D printable files that are available for free to anyone who signs up for a free account. Images include files from normal anatomy to those related to paleontology to complex musculoskeletal tumors. This site was founded by a practicing interventional radiologist with a passion for 3D printing and perfecting an easier method for converting files into those that may be downloaded and printed—a medical 3D printing application called democratiz3D.

Commercial Medical 3D Printing Software

Three-dimensional printing has become a popular research and industrial interest in the orthopaedic surgery world. International companies such as Stryker (www.stryker.com) and DePuy Synthes (www.depuysynthes.com) are now marketing designs in craniofacial reconstruction, arthroplasty, and spine deformity surgery that utilize 3D printing in order to individualize implants and surgical techniques. Specialized software for 3D printing in healthcare is sold by Materialise in an offering called Mimics. Vital Images, a medical imaging and informatics company, has partnered with Stratsys, a 3D printer manufacturer, to provide a segmentation and healthcare 3D printing solution. However, these technologies are costly, and may be cost-prohibitive for the average patient or surgeon.

Three-Dimensional Printing for Patient Education and Surgical Planning

Although most radiology departments currently have the capability to quickly convert a CT (computer tomography) scan to a three-dimensional image for better understanding of a patient’s anatomy, visualized anatomy cannot replace the ability to feel and manipulate a model. Three-dimensional printing can, however, bring these images to life. Printers have the capability to use differing materials, such as polymers, plastics, ceramics, metals, and biologics to create models. These models can be an excellent tool for patient and trainee education as well as surgical planning. In procedures such as complex tumors or difficult pelvic fractures, the surgeon could practice different techniques on an exact replica of the patient’s anatomy so that they have a better grasp of their approach to the patient. Furthermore, trainees currently learn and practice their surgical skills on cadaveric specimens, which can also be costly. Having access to a 3D printer that could create models could potentially decrease the utilization of cadavers.

Free and Easy Medical Three-Dimensional Printing

Creating files from CT scans that can be used in 3D printing is easy with the use of the Embodi3d website. Detailed instructions are available on the tutorial pages of the website, but a brief overview will be described here. CT scans may be obtained from the radiology department in DICOM format. Free software available online at www.slicer.org can be used to review the DICOM imaging, isolate the area of interest and convert to an .nrrd file. This .nrrd file may then be loaded onto the democratiz3D application and formatted in a number of ways based on threshold as shown in the images below.

Files may be opened through the application or dragged and dropped into the file area (Figure 1, Figure 2). Details of the file, such as the title, description of the anatomy or pathology, and keywords are placed beneath the upload (Figure 3). Different thresholds are available to be automatically placed on the uploaded file, including bone, detailed bone, muscle, and skin (Figure 4). These files as well as the final, processed, files may be shared or remain private, free or at a fee to download by the community.

Figure 1. The link to the democratiz3D application is located at the top menu bar of the main page at https://www.embodi3d.com.

Figure 2. Once on the democratiz3D application, you may upload the .nrrd file or drag and drop the .nrrd file into the uploading area.

Figure 3. While the .nrrd file is processing, you may edit the details of the file, such as the title, tags, and description.

Figure 4. The application allows for thresholding of bone, detailed bone, muscle, and skin from the uploaded CT scan.

Once the file has been processed, you receive a notification and may view the file as well as automatically created screen shots (Figure 5). This is now an STL file that may be downloaded by clicking “Download this file”. If this is a file that you have downloaded, you may also edit the details of the file, move it to another category or upload a new version of the STL file directly onto the page (Figure 6). Although the democratiz3D application is a powerful and quick tool to convert .nrrd files to STL files, it is limited by the quality of the CT scan. Therefore, users may wish to clean up the model using free software such as Meshmixer or Blender. Once the files have been edited, they are maintained as an STL file that may be directly uploaded onto the page as a new version (Figure 7). These may then be placed in a category that is most descriptive of the file (Figure 8).

Figure 5. After about 5-20 minutes of processing (depending on the size of the file), you will get a notification and e-mail that the file has processed. The democrati3D application has converted the file into an STL file is now available for downloading and use in 3D printing.

Figure 6. If you would like to change the details, or upload new files or screen shots, you may choose from the drop-down menu.

Figure 7. In order to upload a new version of the file, such as after it is edited in the free software Meshmixer or Blender, you may choose from the drop-down menu and drag and drop a new STL file.

Figure 8. Because Embodi3D has created a library divided into different categories, you may move your file into the appropriate category to allow for ease of sharing with the community.

Alternatively, files that have been downloaded and edited may be uploaded as new files using the “Create” selection on the top menu (Figure 9). Once you have chosen the most accurate category (Figure 10), you can upload the new file by selecting the file or drag and drop into the proper area (Figure 11). This will then take you to similar section as outlined above in order to edit the details and sharing options for your file.

Figure 9. Upload an STL file by selecting the “Create” menu at the top of the webpage.

Figure 10. Select the category under which the file most accurately fits.

Figure 11. Upload the STL file by dragging and dropping or selecting the file.

As you can see, creating STL files from individual CT scans is an easy, 15-20 minute process that is reasonable for the busy orthopaedic surgeon to utilize in their practice.

For educational purposes, however, not every trainee, surgeon, or radiologist has access to patients with such a wide array of pathologies. The Embodi3D community provides an ever-growing diverse library of normal anatomy and pathology that may be downloaded for free and used for 3D printing. The files are divided into categories including: Bones, Muscles, Cardiac and Vascular, Brain and nervous system, Organs of the Body, Veterinary, Paleontology, Anthropology, Research and Miscellaneous.
 

In order to access these files, click “Download” from the top menu (Figure 12), which will take you to the main Downloads page (Figure 13). The categories available are listed on the right side of the page, and will bring you to each category page. There, the number of files available within each category is listed. Once the desired file is selected, the file may be downloaded as described above.

Figure 12. In order to access the library of files, click “Download” from the top menu on the main page.

Figure 13. The Downloads page has a listing of the available categories to browse and explore for the desired files.

Creating and printing 3D models of CT scans will be useful in the future of medicine and the era of individualized medicine. The free library of medical 3D printing files available at embodi3D.com as well as the free conversion application democratiz3D will be an invaluable resource for education as well as for the private orthopaedic surgeon with limited resources. Furthermore, because healthcare costs are a main focus in the United States, having the ability to download and create models for a much lower price than through commercial 3D printing companies will be useful to decrease the cost of individualized care.

For more information about 3D printing in orthopaedic surgery, please see the following references:

1. Cai H. Application of 3D printing in orthopedics: status quo and opportunities in China. Ann Transl Med. 2015;3(Suppl 1):S12.
2. Eltorai AEM, Nguyen E, Daniels AH. Three-Dimensional Printing in Orthopedic Surgery. Orthopedics. 2015;38(11):684-687.
3. Mulford JS, Babazadeh S, Mackay N. Three-dimensional printing in orthopaedic surgery: review of current and future applications. ANZ J Surg. 2016;86(9):648-653.
4. Tack P, Victor J, Gemmel P, Annemans L. 3D-printing techniques in a medical setting: a systematic literature review. Biomed Eng Online. 2016;15(1):115.