Although 3D printing is revolutionizing prosthesis manufacturing, enabling fast, accessible, low cost production, aesthetics is lagging behind. The Exo-Prosthetic leg could be an alternative to the traditional "robotic" prosthesis, using 3D scanning, modeling and printing technology to create a customizable titanium exoskeleton that replicates the exact form of the amputated limb.
There are over 2 million amputees in the United States with 185,000 amputations every year. More than 90 percent of these involve amputations of the lower limbs.
While standard prostheses help patients regain much of the freedom and functionality they have lost, they come at a financial and psychological cost.
Traditional prostheses can be prohibitively expensive due to their complexity and the specialized labor required to customize them for each patient. They also have a very mechanical and robotic look and feel about them, which can exacerbate the sense of loss and negatively affect the psychological wellbeing of some amputees.
We’ve seen many low cost prostheses as a result of 3D printing, such as the arm and hand developed by teenager Easton LaChappelle, the "Robohand" and the JaipurKnee, all of which have the potential to make prostheses more accessible.
However, industrial designer William Root's Exo-Prosthetic leg also acknowledges the importance of beauty in prosthesis design. Root believes the unaesthetic appearance of prosthetic limbs is the result of the flawed and outdated process of producing them.
His Exo-Prosthetic leg looks to modern technologies to streamline the manufacturing process. By using a combination of 3D scanning, 3D printing and 3D modeling software, Root believes the entire process can be automated to create a customizable, affordable and beautiful product.
The patient’s residual limb and remaining intact limb, if present, are first scanned to create a highly precise 3D virtual model, allowing the anatomy to match up within fractions of a millimeter.
During this process the FitSocket technology, developed by the Biomechatronics lab at MIT, also captures leg tissue properties allowing a better fit – and therefore increased comfort – between the residual limb and socket.
The scans of the intact leg, residual limb and off-the-shelf prosthetic mechanisms are then combined in a 3D mesh model to create the raw model of the prosthesis.
To reduce weight, the limb is hollowed out forming an exoskeleton. The surface pattern of the exoskeleton can be customized with patterns and colors to suit the client, or it can later be used as a scaffolding for a silicone sleeve.
The finished model is sent to a 3D printer and printed out of titanium, an extremely durable, lightweight and biocompatible metal. Titanium dust particles are fused together using laser sintering.
Printed as a single 3D exoskeleton it is immediately ready for assembly. Using custom connectors 3D printed directly onto the prosthesis, off-the-shelf prosthetic components are inserted into the Exo leg, and it is securely assembled using a standard pyramid connector.
Far from being the conventional robotic, mechanical compilation of parts we've come to expect from prostheses, the Exo takes on the form of the wearer's own body, hopefully creating a more human and intimate connection for them.
The next stage will be to develop a fully functional prototype and determine the structural requirements.
The Exo has received a lot of interest. Root is considering how best to apply the new method to existing systems, and whether it would be most effective being taken up by a startup, a 3d-printing company or a big player in the existing prosthesis marketplace.
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