Remember when you were a child and broke your arm and had to wear a heavy, hot plaster cast in the Summer? Your arm felt heavy and itchy, your muscles atrophied, you had to wear a plastic bag over your cast to shower, and, after a couple of weeks, the cotton padding inside stunk. The only good thing about it, besides your broken bone being allowed to heal, was that your friends got to sign your cast and draw funny pictures on it. Fiberglass casts offered some improvements. They are lighter and more durable than plaster, X-rays can penetrate better, and they are available in different colors. But there’s still the matter of padding, which shouldn’t get wet.
Flash forward to today and that’s all starting to change — thanks to 3D printing.
After breaking his own hand last year and being fit with a conventional cast, Jake Evill, a New Zealander with a degree in industrial design, designed what he calls a Cortex exoskeletal cast, based on the honeycomb shape that forms the inner structure of actual bone. It’s a 3D-printed design that’s beautiful to look at, fully ventilated, very light, shower friendly, and recyclable. It utilizes an X-ray of the break, along with a 3D scan of a patient’s limb, to generate an anatomically correct two-part cast with localized support in relation to the point of fracture. His design was a runner-up for the thirteenth annual James Dyson Award, global product design competition.
Another latticework cast, the Osteoid Medical cast, created by Deniz Karasahin of dk design, recently won the international A'Design Award and Competition in 3D Printed Forms and Products Design category for 2013-2014. The Osteoid medical cast introduces an additional option—it can be combined with a low intensity pulsed ultrasound bone stimulator system, which may reduce the healing process up to 38 percent and increase the heal rate up to 80 percent in non-union fractures. The design was the outcome of a four-month clinical trial of 67 patients with fractures of the tibia. He said that the most difficult part was to come up with a fully functioning locking mechanism for the two-part design that was strong, practical, and yet simple enough to not disturb the cast’s form.
While these designs are not yet in actual production, braces and splints of all kinds can be customized to improve the fit, allow better hygiene, and impart a clean, modern look. On page 25, we highlight a 3D-printed scoliosis brace, which looks like a beautifully patterned corset.
These are in addition to the myriad of other ways that 3D printing will, and already is, impacting medical devices, such as joint replacement components; implantable discs; prosthetic limbs, hands, and feet; dental uses; skull implants; facial prosthetics; and implantable airways. Many of these uses have already been covered in Medical Design Briefs, with many more to come.
As the printers continue to come down in price and become more widely used, they will continue to revolutionize the look and appeal of medical devices. And, they will allow medical product designers to be more creative as well.
Although a cast is far from the most life-saving of uses for 3D printing, as the Summer winds on and casted kids gaze longingly at swimming pools while their friends splash happily, a kinder cast seems like a great use of the technology.
Beth G. Sisk