By Andrew Hanson, Applications Engineer, Stratasys and Scott Rader, General Manager, Medical Solutions, Stratasys
[caption id="attachment_125701" align="alignright" width="186"] Traditional ankle-foot orthotic[/caption]
Orthoses, often referred to as orthotics, are passive devices worn by people to support an injured or weakened body part. While many people will be familiar with the use of temporary braces after an injury, a significant proportion of orthotics are used for long term care to address multiple conditions. These conditions include foot drop from muscle weakness or neural damage due to suffering a stroke, multiple sclerosis, peripheral nerve injuries and other disease processes. Orthoses are also used to assist stabilizing a painful osteoarthritic joint, and correcting a joint deformity.
With aging populations worldwide, the number of people who utilize orthoses has grown significantly in the past three decades. Projections indicate that 7.3 million people in the United States will utilize orthoses to combat the effects of paralysis, deformity or orthopedic impairments by 2020.
But while demand increases, manufacturing techniques have not changed dramatically in decades.
CYBER Team, aiming to revolutionize orthotics using Industry 4.0
The University of Michigan has partnered with Altair Engineering and Stratasys to form the CYBER team. And the CYBER Team was recently selected and funded by America Makes (the National Additive Manufacturing Innovation Institute) to work together on a solution that will leverage 3D printing and Industry 4.0 to transform the design, comfort, utility and customization of Ankle Foot Orthotics (AFO). This solution will incorporate digital design, additive manufacturing through 3D printing, and leverage industry leaders at the University of Michigan Orthotics and Prosthetics Center to deliver on emerging Industry 4.0 trends.
In order to accomplish this, the CYBER team will create the digital workflow for additive manufacturing (AM) design, while connecting the digital thread in a cloud-based cyber physical system which will connect fused deposition modeling (FDM®) additive manufacturing technology and Altair® OptiStruct® software for the production of customized ankle-foot orthoses (AFO).
The Pain Point of Ankle Foot Orthotic Manufacturing Today
The traditional process for making a patient a customized AFO uses (A & B, see image below) skilled orthotists and technicians to take an “impression” of an individual’s lower leg with fiberglass cast tape; (C) pouring liquid plaster into this impression to create a positive model; (D) modifying the plaster model by hand to account for bony prominences as well as pressure tolerant areas (E) vacuum forming a thermoplastic sheet around the model; (F) hand-trimming the plastic orthosis to final shape; and then adding any necessary padding and straps before fitting the AFO to the patient1.
[caption id="attachment_125700" align="aligncenter" width="510"] Traditional process for making custom ankle-foot orthotics[/caption]
The pain points of this process starts with a typical delivery time of two to four weeks due to the skilled labor required, insurance authorization processes, and the demand on this resource from the numerous patients requiring this care in orthotic centers. The process uses a significant amount of disposable plaster materials, has limited capability to optimize the structure or the weight due to a constant sheet thickness across the orthosis, and does not incorporate modern analytical techniques that ensure optimization of the strength and flex of the AFO to maximize a patient’s mobility.
“While custom AFOs have always been created with a patient’s custom shape, additive manufacturing provides improved possibilities to truly customize the manufacturing of an AFO. The ability to adjust trim lines and alter the type or thickness of plastic has provided some basic options for tuning the flexibility of an AFO,” said Jeff Wensman, BSME, CPO, Clinical/Technical Director, University of Michigan, Orthotics and Prosthetics Center. “But, additive manufacturing, and specifically the CYBER team, is creating a process to actually ‘engineer’ and ‘design’ an AFO for a specific patient. Different amounts or types of material can be printed to provide a specified stiffness and allow areas of flexibility, based on the patient presentation. This exciting technology opens up an entirely new tool box that the clinician can use to enhance patient outcomes.”
The CYBER Solution: Making Industry 4.0 Real in Ankle Foot Orthotic Manufacturing
[caption id="attachment_125704" align="alignright" width="300"] Stress loading and concentration analysis will allow for AFO part optimization, tailored for individual patient prescriptions[/caption]
The CYBER team has come together to directly address these pain points that affect patients and care-givers, while accelerating and reducing the cost of delivery of optimized ankle foot orthoses.
This future cloud-based cyber physical system will allow clinicians to create Ankle Foot Orthoses by utilizing an online portal, combining clinician expertise with automated tools to create the patient’s prescription. The engineered cyber-physical system provides the seamless integration of the cloud based algorithms with the physical component manufacture to optimize overall part geometry and its corresponding tool-paths.
The advantages of an additive manufacturing solution for Ankle-Foot Orthoses are compelling:
- Reduce the long delivery time: Typical delivery time is 2-4 weeks for AFOs. The team plans to reduce this delivery time to 1 day through the cyber-physical system.
- Enhance the level of accuracy: Plaster shrinks after drying so plaster molds do not accurately duplicate the patient’s ankle and foot shape without iterations or the skill of a certified orthotist. The team plans to utilize precise, 3-dimensional scanning to provide exact dimensions for instant, exact AFO accuracy while utilizing design for additive manufacturing compensation techniques.
- Eliminate multiple visits: This is taxing for users and caregivers, and drives cost.
The team plans to improve the manufacturing process to provide single-visit patient care.
- Enhance the limited design freedom: Shapes of AFOs are limited by current manufacturing practices, which cannot fabricate orthoses that require more intricate, functional designs.
The team plans on allowing computational model and tool path based optimization to drive future AFO design, while encouraging clinician input to provide personalized care. The average age of a lower extremity orthotic wearer is 70 years old; light-weighting and ease of use are paramount in this project.
Of course, no one person can properly execute all of the required knowledge to operate the current workflow needed to achieve this cyber-physical system. Engineers, such as those at Stratasys and Altair, along with clinicians at orthotics & prosthetics centers, are the only people knowledgeable enough to execute each specific task. Between multiple file types, the creation of structural and tool path optimization files, design for additive manufacturing considerations, and orthotic best practices, the amount of manual computational analysis is daunting. Adding to the expertise needed, the current additive manufacturing workflow has drawbacks:
- Machine throughput: The current additive manufacturing technologies do not provide high enough throughput to enable the one-day visit for ankle-foot orthotics. A new design methodology is required to increase throughput and lower material usage, while maintaining structural integrity and functionality.
- Multiple materials: Both stiff material for structural functionality and a soft material for comfortable interfacing are needed in one custom orthosis.
- Lack of clinical interface and system integration: There is no software system that can seamlessly process all the data from the patient’s 3D scan geometry to shape of the orthosis, and to the printable command file.
Military Veterans May Be the First to Benefit
Aligning with the team’s commitment to military veterans and their families, the US Veterans Administration (VA) in Ann Arbor, Michigan will be one of the first partners to receive this solution with the goal of deploying it to VA Orthotics & Prosthetics locations nationwide once testing is complete. From 2005 to 2009, the annual VA spending on O&P related items has increased almost 80%, from $907M to $1.6B. About 1.5 million orthoses were provided to veterans in 2009. These numbers are continually growing as the number of enrollments in VA Healthcare increases with the aging of the overall population. As concluded in the American Orthotic Prosthetic Association (AOPA) study, the savings for Medicare could be $1.3B per year by 2020 after full deployment of this solution to the VA network.2
[caption id="attachment_125702" align="alignright" width="306"] The Cyber-Physical System workflow[/caption]
The CYBER team believes that cloud-based design and additive manufacturing technologies provide the opportunity to improve healthcare professionals’ care to patients, with a goal to achieve a “One-Day Visit” in which patients can visit a clinic and walk away in their custom orthoses on the same day. Integrating additive manufacturing into orthotics and prosthetics patient care is an opportunity for the manufacturing community to make a positive impact in healthcare; the success of this project is expected to make the manufacturing process more efficient and reliable, so that orthotics and prosthetics service can be more accessible to people who need it saving VA Healthcare and Medicare expense.
This project is scheduled to complete its proof-of-concept in 2017.
This material is based on research sponsored by Air Force Research Laboratory under agreement number FA8650-12-2-7230. The U.S. Government is authorized to reproduce and distribute reprints for Governmental purposes notwithstanding any copyright notation thereon.
The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of Air Force Research Laboratory or the U.S. Government.
1. Patient specific ankle-foot orthoses using rapid prototyping, Mavroidis et al., January 2011. Link: http://jneuroengrehab.biomedcentral.com/articles/10.1186/1743-0003-8-1
2. Data available at http://mobilitysaves.org/