3D Printed Back Brace for Scoliosis

Background Info on scoliosis:

Scoliosis is a sideways curvature of the spine that is most often diagnosed in adolescents. While scoliosis can occur in people with conditions such as cerebral palsy and muscular dystrophy, the cause of most childhood scoliosis is unknown. Most cases of scoliosis are mild, but some curves worsen as children grow.

Project Overview & Context:

I am a student currently studying Biomedical Engineering at Temasek Polytechnic. I am currently working on my final year group project with 2 other students where the objective is to design and develop an eco-friendly prosthetic back brace that will improve comfortability and breathability from an existing brace.

Furthermore, we want to incorporate interchangeable parts to the design. After many days of brainstorming, we wanted the scoliosis brace to be unique and innovative. The idea of an interchangeable aspect sounded ridiculous at first as it had never been done before. Albert Einstein once said, “Scientists investigate that which already is; Engineers create that which has never been.” We were determined to turn our idea into a reality.

We started this journey with no prior knowledge of scoliosis, but only with an idea. We haven’t even heard of CAD modeling before this project as we are biomedical students, but we took it as a great opportunity to learn something new. 

Okay enough about us

Why comfortability, breathability, and interchangeable parts?

After conducting a survey (pie chart shown above) of many people suffering from scoliosis, the main takeaways were uncomfortable, restricted movement, bulky, and price. We tackle these issues by incorporating hexagonal cutouts (10mm diameter) with a spacing of roughly 12mm apart provides breathability and removes roughly 10% of the volume of the brace without affecting much of the structural integrity of the brace, ensuring effectiveness of the brace.

We incorporated a water barrier method which is essentially like a lock and key model, where there is a male (a protrusion)and a female part (a hole). This method allows us to join the parts together without using external materials like metal screws or rods

We incorporated the interchangeable parts in order to tackle the solution of cost. The idea is that when the spines continue to readjust, the brace would not be effective anymore. Therefore, the patient needs to buy a new brace for the new curvature. We intended it to be interchangeable so that the patient does not need to replace the whole brace and instead just change the curvature of the brace

As the brace scanned and designed is customised for one person, in this instructable, I plan to go through what was done to design the brace so you can try to do it as well with a 3d body scan. Do forgive us if we designed it poorly or too simply as we just learned Fusion 360 a month ago.

Material:

• PolyTera PLA Filament

Hardware:

• 3D Printer (Raised3D Pro3)

• Shining EinScan Hybrid 3D 

Software:

• Fusion 360

• EinScan H software

The picture above is the brace scan on the EinScan H software.

We were fortunate to have a handheld scanner which made the scanning of the brace much easier. The existing brace was scanned using the EinScan Hybrid 3D scanner. Obviously, many problems appeared when trying to scan for the first time, for example, connection issues and the scanner being unable to scan the brace properly. But after numerous tries, we managed to get a good scan!

The design process is quite lengthy so do bear with us.

While researching how to use CAD software to design the brace, I stumbled upon a YouTube video on surface modeling on Fusion 360. Initially, I got attracted to the user-friendly interface. Furthermore, there is a free educational account for students in Fusion 360 which confirmed our intention to use the software to help aid us in our design.

Now on to the design stage.

The scanned brace was first imported to Fusion 360 and using “Plane Cut” under Mesh, I trimmed away redundant parts of the brace that we do not want to include in the design. This is followed by rotating the brace using the move function to reduce the angle it is slanting.

After adjusting the brace position and removing unwanted parts, I converted the brace from mesh to t-spline. As the brace is made of organic shapes, I decided to manually create the t-spline for more accurate results by using “Form by planes” where I can select the plane at which I would like to create my form and the number of faces per row and column. I then used “Edit Form” to align the faces to the shape of my brace.

To make things easier, I toggle between the different opacity for a clearer vision of the internal parts of the brace. The picture above shows the product of the t-spline after many attempts of aligning the faces to the brace.

I then converted the t-spline to surface as I needed to add additional parts of the brace for the water barrier to work. Under “Form”, select utilities and convert t-spline to B-rep.

To ensure that the brace is safe to use, I trimmed the sharp edges by using the sketch tool under the surface tab. I traced the lines of a standardised distance of 10mm/20mm that join to form the sharp edges using Line or Arc. After having the endpoints of the 2 lines, I used Conic Curve to sketch a smooth parabola curve on the surface. Then, I select Trim and selected the two lines and the parabola curve drawn to remove it.

To create the water barrier method, there are two separate parts, the hole, and the stick. To attach the stick and extrude a hole, we have to work on the surface of the brace first. Starting with designing the surface related to the stick, with the calculated dimensions, I sketched 35mm (Breadth) by 30mm (Length) and trimmed the area away for the stick to be attached.

On the other hand, as we would like to put the brace together, we have to extend parts of the brace to ensure that when we fit the stick into the hole, the size of the brace would remain the same and not be reduced. Hence, to extend parts of the brace, using “Spline”/ “Arc” under sketch, I traced the path of the brace. This path is then duplicated and shifted to the left by 35mm (Breadth). Now, we fill the sketch with the surface using Patch and click on the lines that surround the area. Then, join the new surface as it is separated from the original surface using Stitch.

At first, I tried to use the volumetric lattice on the scoliosis brace but the software would always crash when I did it. So I manually drew the hexagons.

I sketched the hexagons 10mm in diameter. Next, I used the rectangular pattern to draw multiple of the same hexagons and spaced them evenly 12mm apart. I then used Trim to cut out the hexagons from the surface. Repeat the steps throughout the brace except for some parts with extreme curvature.

Now for the last part of the design

Firstly, I thickened the brace to a thickness of 7mm (0.7cm) as the brace should not be very thick.

In the previous part of the design phase (when the brace is still a surface) we have extended some areas for the stick to be attached.

Due to the organic shape of the brace, we are unable to extrude a circle directly to get the stick as it would not follow the path of the brace. Therefore, instead of using the direct extrusion method, I traced out the path of the brace using Plane along Path, similar to what I did for the extension of the area. I then duplicate that line and adjust the position to ensure it is in the middle (thickness/2, length/2).

Next, I drew a circle as I want to attach the stick along the path of the brace. After sketching, I used Sweep to extrude the stick along the path of the brace.

Lastly, for the hole, we will be using the same method as we did for the extrusion of the stick. The only difference is the operation will be cut instead of join.

We then 3d printed the brace. We split the brace into a total of 8 parts of different sizes. Some parts took way longer than the others but the average printing time of each part is around 17-18 hours.

As 3D prints aren’t always perfect, we used sandpaper to sand some of the rough edges on the surface.

We are very proud of ourselves that we are able to accomplish this prototype in 2 months. Having no prior knowledge of these fields, we were very skeptical if we could even make a prototype. However, we managed to pull through. We managed to learn so much in a short amount of time such as CAD modeling, 3D printing, etc. Thank you for taking the time to read through our lengthy instructable and hope u learned something new as well.

This is not the last of us, we still have so much to improve and learn from after creating this prototype. We look forward to improving our design and skills and we will keep you all updated when we are finished with our next prototype!

Thank you!