3D printed prosthesis

In the United States roughly 5.6 million people have limb differences. One of the biggest barriers of individuals attaining prosthetic devises is the high cost. 3D Printed prosthesis act as a low cost alternative to standard prosthesis devices.

Background

Robohand available on Thingiverse as an opensource 3D printable prosthesis

The first 3D printed prosthetic was designed in 2011 after a carpentry accident caused for Richard Van As to lose two fingers. As he wanted to get back to work, but wasn't able to afford a prosthetics, he looked to other options where he met Ivan Owen, a performer and puppeteer. Ivan had designed a large puppet hand which was able move its mechanical fingers. After working together, creating a mechanical body powered prosthetic for Van As, they realized that there was potential in use of a 3D printer for faster redesign. Eventually they created a 3D printed version, "Robohand", in which they posted on Thingiverse along with instructions on construction .

3D designing custom prosthesis

3D Printed body power prosthetic devise showing some available aesthetic customizations

The design starts with creating an accurate 3D rendering of the residual limb. This can be done in a few ways, such as 3D scanning, MRI, CT scan, or digital image reconstruction . A prosthesis can then be design by integrating the rendering into an existing design . Depending on the design, different 3D printing manufacturing methods can be used. After printing, post processing occurs, some processes like SLA require the for the curing of the part, others like FDM require light clean up. Additional hardware, from support rods to bolts or wire is then added before the final assembly.

3D Printing allows for rapid prototyping, which has shown benefits within clinical settings. This is especially important within custom sockets. The socket is the main interface between a user and the prosthesis properly fitting is important for both comfort as well as allowing for proper function. Control of the prosthetic, as well as force distribution is primary control through the socket . 3D printings rapid prototyping allows for this to be better honed in ensuring a better fit.

Limbitless Solution bionic arms

Aesthetic customizations are also more available with 3D printed prosthesis. Aesthetics along with involvement within the design of a prosthesis both have shown improvements of individuals self esteem. In turn, this leads to better reception of an individual for a prosthetic . For at home, or open source designs, this can come in the choice of various colors and sometimes even various textures and designs. Projects like Limbitless Solutions, a non profit which focus on prosthetics for children, have interactive websites allowing for individuals to create a custom design of their prosthesis like adding their own multi color designs. Additionally, they have also worked with artists and designers to create custom designs that children can choose.

Open source design

Opensource 3D printed body powered prosthetic devise

Open sourced designs for prosthesis allow for an especially low cost alternative. Built from collaborative efforts of various people, opensource designs can have a wide range. Projects like Enable have walk through guides on building and assembly, along with a community out reach program connecting people looking to get a prosthetic with a volunteer that can build it for them . Other projects like Cyborg beast work on creating specialized prosthesis devise for kids. Some projects, have various options that people can choose from depending on the level of limb difference as well as the general size. Other programs allow individuals to input custom parameters for tailoring and getting an individualized fit.

One draw back of opensource designs is while 3D printing and design is very accessible, it does not mean that everyone can receive the same results. When prosthetics are designed with considerations of forces, and material properties, they are able to be optimized, allowing for more more successful prosthetics. Additionally, experienced designers are better able to follow FDA guidelines which is important within the medical felid . It is also worth noting that standardizations within testing allow for a more comprehensive comparison along with better characterization of the devise. Often projects will only consider the weight, printing speed, or cost of the devise rather than mechanical properties.

Work on solving these issues is being done, like at Carnegie Mellon University, in which Lee et al. researches the use of machine learning to characterize the mechanical properties of 3D printed parts. Their process allows for individuals to use a smart phone to take multiple photos of a residual limb, then digital image reconstruction allows for 3D mesh to be created. The 3D rendering is then implemented into a prosthesis devise using pre-designed assembly where possible. This allows for a better understand of material properties based on previous testing.