“There is a tremendous amount of engineering that goes into any prosthetics,” as Connelly says, but 3-D printing can still help create prototypes as engineers move toward an end goal.
For example, in 2009, then-25-year-old Joel Salder was honored by TIME for having one of the best 50 inventions that year—a prosthetic knee that only cost $20. The Stanford University Bio-X fellow used 3-D printing “to find out what forms work really well for a knee joint” when creating the JaipurKnee.
That’s one of the biggest advantages of 3-D printing, the ability to quickly print highly customizable forms. This opens the practice up to mechanical extrapolations, such as producing cheaper components for traditional prosthetic limbs.
Take Willow Wood, a company that produces prosthetic limbs and components. “We can print out a socket that can be used definitively, but attached to that socket is generally some sort of suspension device,” says director of research Jim Colvin. “To print that [component] in the same printer is not possible today.… You’re trying to replace a part of the body, and that part of the body isn’t homogenous.”
Still, by using either traditional casting or a combination of digital modeling software and laser body scanning to gather the geometry of the stump, the company successfully prints sockets, saving both time and money without sacrificing customization. It’s progress, but it isn’t the same as being able to have a fully-created prosthetic limb hot off the printer.
“There’s a dream that in the future, we’ll be sitting in our home and hit a button to print our prosthetics from scratch,” Sadler says. “That might be a further out vision.”
But some people think we’re already there.
The 3-D Printed Prosthetics of Today
Sadler agrees with Kuniholn about the difficulty of attaching printed prosthetics, saying, “The fitting is a whole other black art. 3-D printing only gets you part of the way.” Of course, that’s for high-end prosthetics, the kind you hope to have. In some parts of the world, the choice is between having a mediocrely-fitting prosthetic and not having one at all. This is the situation that spurred Summit to action, as well as Patrice Johnson, who, according to Sadler, is, “the only person to have successfully designed and sold [a] functional upper limb prosthesis that used 3-D printing.”
Johnson was the former chief technical officer of Physionetics, a start-up company that successfully created both the hook hand replacements and sockets of upper-limb prosthetics that could be 3-D printed.
These limbs were printed on a $500,000 3-D printer owned by ExOne. This particular printer, housed in Pittsburg, can print metal, a stronger material than the plastic of most printers. While attempting to create a cheap prosthetic arm that could be used by people around the world, Johnson found that “in the long-term, it made much more sense, just from a money sense, to use 3-D printing” citing “one of the ways that it made a crucial difference for us is if you had a good idea … you’re quickly able to create your good idea and see if it’s feasible.”