3-D printed orthotics and prosthetics: A better fit, the same day


A new way to design and 3D print custom prosthetics and orthotics could give amputees, stroke patients and individuals with cerebral palsy lighter, better-fitting assistive devices in a fraction of the time it takes to get them today.

ANN ARBOR – A new way to design and 3D print custom prosthetics and orthotics could give amputees, stroke patients and individuals with cerebral palsy lighter, better-fitting assistive devices in a fraction of the time it takes to get them today. Developed by the University of Michigan College of Engineering, the system is being implemented at the University of Michigan Orthotics and Prosthetics Center (UMOPC).

The U-M engineers and clinicians who designed the new cyber manufacturing system say that shortening the fabrication time for custom orthotics could make the process easier on custom assistive device users, who today must wait days or weeks to receive essential orthotics and prosthetics. The digital design and manufacturing process can also improve the devices’ precision, fit and function and improve consistency from one provider to the next.

Prostheses are devices used to replace a lost limb, while orthoses are braces used to protect, align or improve function or stability to injured limbs. Currently, the U-M team is focusing on ankle foot orthosis, which are often prescribed to stroke patients to help them regain their ability to walk. More than two-thirds of the 700,000 stroke victims in the United States each year require long-term rehabilitation, and many of them can be helped with custom orthotics. The devices can also help children with cerebral palsy, myelomeningocele and other conditions gain stability and walk more easily.

“Eventually we envision that a patient could come in in the morning for an optical scan, and the clinician could design a high quality orthosis very quickly using the cloud-based software,” said Albert Shih, a professor of mechanical and biomedical engineering at the University of Michigan and the lead on the project. “By that afternoon, they could have a 3-D printed device that’s ready for final evaluation and use.”

The new technique begins with a three-dimensional optical scan of the patient. The orthotist then uploads the scan data to a cloud-based design center and uses specially developed software to design the assistive device. Next, the software creates a set of electronic instructions and transmits them back to the orthotist’s facility, where an on-site 3-D printer produces the actual device in a few hours.

Jeff Wensman, director of clinical and technical services at UMOPC, says the new process is a major departure from current methods, which begin with wrapping fiberglass tapes around the patient’s limb. The tapes harden into a mold, which is then filled with plaster to make a model of the limb. Next, heated plastic is formed around the model in a vacuum forming process to make the actual device. The device is then hand-finished by smoothing the edges and attaching mechanical components like straps. It’s a labor-intensive process that requires a large shop and a highly trained staff. By contrast, the only on-site equipment required by the new process is a optical scanner, a computer and a 3-D printer. In the future, this could give even small clinics in remote areas the ability to provide custom orthotics and prosthetics.

The lighter weight of the 3-D printed devices stems from a technique called “sparse structure,” which can make orthotics that are partially hollow using a wavy internal structure that saves weight without sacrificing strength. Developed by U-M mechanical engineering PhD student Robert Chisena, sparse structure was initially intended as a way to print orthotics more quickly, but researchers quickly realized that it could make them better as well.

“Traditional hand-made orthotics are solid plastic, and they need to be a certain thickness because they have to be wrapped around a physical model during the manufacturing process,” Wensman said. “3-D printing eliminates that limitation. We can design devices that are solid in some places and hollow in others and vary the thickness much more precisely. It gives us a whole new set of tools to work with.”

Because the 3-D manufacturing process uses computer-based models rather than hand fabrication, it’s also more consistent than current methods. Any clinic with a 3-D printer could produce exactly the same device time after time. In addition, computer models of previous orthotics can provide doctors with a valuable record of how a patient’s shape and condition progress over time.

The current 3-D printing device is already turning out orthotics and prosthetics for testing; Shih says the team is working to demonstrate how it can reduce costs and improve service and efficiency. Eventually, they plan to make the system’s software and specifications freely available so that other healthcare providers can roll out similar systems on their own.

“In a sense, we’re building a recipe that others can use to build their own systems,” Shih said.

The project is funded by the National Science Foundation and America Makes, a partnership between industry, academia, government and others that aims to develop advanced manufacturing and 3-D printing capabilities in the United States. Software for the project is being developed by Altair and Standard Cyborg. Stratasys provided the 3-D printer for the project.

“Without America Makes and Manufacturing USA, we would not be able to bring a state-of-the-art 3D-printer to the prosthetics center with the traditional research project,” Shih said. “Without the National Science Foundation’s Partnership for Innovation and cyber manufacturing grants, we would not be able to have PhD engineering students working at UMOPC to develop the system. I am very blessed to have all three projects funded and started at the same time to create this first-of-its-kind demonstration site at UMOPC for the Michigan Difference in advanced manufacturing and patient care.

Histotripsy, a non-invasive cancer treatment

Michigan Engineering Professor Charles Cain outlines a new technique called “Histotripsy,” which is a non-invasive ultrasonic approach for the treatment of benign disease and cancer. Cain says the knifeless surgical approach generates energetic microbubbles that oscillate very rapidly, almost like a “nano-blender.” The procedure can be used for multiple applications, including treating newborn infants with heart defects, prostate patients and potentially diseases such as breast cancer.

ABOUT THE PROFESSOR: Professor Cain is the Founding Chair of Biomedical Engineering at the University of Michigan and the Richard A. Auhll Professor of Engineering. He and his research team have been developing the histotripsy technique for the last five years.

Predicting your risk of illness

Imagine a future when you could predict whether or not you are at risk of becoming sick. U-M professor Alfred Hero is working to make that a reality with his research into the human genome’s response to viral illnesses. Hero’s group is working to build a mathematical algorithm that can predict whether or not an individual is susceptible to a virus. He envisions a future where a personal device could be used to monitor that individual’s risk factor, thereby changing the field of preventive medicine.

ABOUT THE PROFESSOR: Alfred Hero is the R. Jamison and Betty Williams Professor of Engineering. He works in the Electrical and Computer Engineering and Biomedical Engineering departments at the University of Michigan. His research interests include probabilistic models for high dimensional datasets, graphical models for multivariate data and information theoretic surrogates for signal and image processing.

Lab on a Chip

Scientists at the University of Michigan are developing microfluid devices to better develop and test human cells. Their three-dimensional cultures create environments that more closely mimics that of the human body than the traditional flat petri dish. With this research, Professor Shuichi Takayama hopes to reduce the cost of drug development and advance disease treatment by provided miniature environments that mimic parts of the human body.

ABOUT THE PROFESSOR: Shuichi Takayama is a professor of Biomedical Engineering and Macromolecular Science and Engineering at the University of Michigan. His research includes the development of microfluidics and micro/nanotechnology platforms capable of testing cells and subcellular components with combinations of mechanical, chemical, electrical, topographical, and thermal stimuli.

HIV testing in developing nations

University of Michigan scientists are developing a device using nanofabrication that would more effectively analyze a blood sample to test for HIV in the developing world. The device, which uses silicon micro-fabrication, has 10,000 micro-holes that act as craters, allowing the blood cells and platelets to pass through while the large white blood cells are captured and counted.

ABOUT THE SCIENTISTS: The team involved in the project include Associate Professor of Mechanical, Biomedical and Macromolecular Science and Engineering Nikos Chronis, as well as engineering PhD student Anurag Tripathi and Dr. James Riddell, an infectious disease specialist at the U-M Department of Internal Medicine.

Meningitis: Steps to prevent future contamination

U-M researchers discuss how a recent outbreak of fungal meningitis distributed through spinal steroid injections has once again brought to light the difficulty of compounding pharmaceutical companies to maintain quality control over their products. Professors Kotov and Wang explain how a combination of better oversight and easier testing methods could ultimately help prevent issues like this in the future.

ABOUT THE PROFESSOR: Henry Wang is a professor of Chemical Engineering and Biomedical Engineering at the University of Michigan. His research interests include the global healthcare sector, comprised of pharmaceutical, biotechnology, medical device companies, regulatory agencies such as FDA, healthcare providers, insurers and consumers.

Nicholas A. Kotov is the Joseph B. and Florence C. Cejka Professor of Engineering. He is committed to engaging in the “most creative, forward looking, and unorthodox scientific and engineering discoveries.” He runs The Kotov Lab at the University of Michigan.

Stretchable conductors

Polyurethane studded with gold nanoparticles can conduct electricity even when stretched, Michigan engineers have discovered. This feat could pave the way for flexible electronics and gentler medical devices. The nanoparticles start out randomly arranged, but they drift into wire-like formations as the material is stretched.

About the Professor: Nicholas Kotov is the Joseph B. and Florence V. Cejka Professor of Engineering and a professor of chemical engineering, biomedical engineering, materials science and engineering and macromolecular science and engineering at the University of Michigan College of Engineering. His research interests include the 3D self-organization of nanoparticles and cells, and in using these principles to improve technologies and health care.

Can we print the human body?

3D printing is revolutionizing the world, and the field of medicine is no exception. U-M researchers are already printing replacement human body parts such as ears and noses. We asked Biomedical Engineering Professor Scott Hollister to explain the process to us, and what he believes the long-term outlook is for printing the human body.

ABOUT THE PROFESSOR: Scott Hollister is a professor of Biomedical Engineering at the University of Michigan College of Engineering. His research group, the Scaffold Tissue Engineering Group (STEG), develops biomaterial platform systems (termed scaffolds) for tissue reconstruction. The STEG specifically focuses on the computational design, manufacturing and pre-clinical testing of degradable scaffold material systems.