Researchers at the VA Center for Limb Loss and MoBility are improving the patient prescription process by bringing together research, clinician knowledge, and patient care.
Each year in the U.S., more than 150,000 people undergo lower limb amputation (LLA).(1) Many of these new patients will enter into the rehabilitation process, working with prosthetists and clinicians to be fitted with a prosthetic limb and restore mobility.
While enormous advances have been made in the field of prosthetics for LLA, the struggle for both patients and clinicians alike is still very real. Mobility goals, comfort levels, injury prevention, insurance coverage and cost restrictions—the prescription process is full of complex considerations, and it’s far from perfect.
To clinician Beth Halsne and engineer Anne Turner from the VA Center for Limb Loss and MoBility (CLiMB)—a research group based in Seattle focused on preserving and enhancing mobility in Veterans and others with foot and leg impairments or amputations—providing more evidence-based research that clinicians can utilize in the prescription process is key to moving the needle forward for LLA patient outcomes.
On a team led by David Morgenroth, M.D., Halsne and Turner are working with Humotech to explore big questions that bridge the divide between research, clinician knowledge, and patient care. Questions such as:
Could a “test drive” of prosthetic feet, actual or emulated, in the lab predict long-term satisfaction and performance with commercially available feet?
For patients, trying out a range of different commercially-available feet at a clinic can be extremely time-consuming and research suggests it may not always lead to the best patient outcomes. By examining various performance and balance measures as well as patient-reported outcomes, Morgenroth, Halsne and Turner are investigating whether or not emulating commercially-available feet in the lab using Humotech’s Caplex system can predict a person with amputation’s long-term preference for a particular foot.
Funded by the Department of Defense Orthotics and Prosthetics Outcomes Research Program (OPORP), the team hopes the study will overcome the current limitations for selecting the best option for the patient, supplementing the current prescription process and making it more patient-centered. Collaborators on the study centered at the VA Puget Sound Health Care System in Seattle include Humotech, the Brooke Army Medical Center, and the Minneapolis VA Health Care System.
A Closer Look at Forefoot Stiffness
One aspect of the study involves researching the effects of mechanical properties of commercially-available prosthetic feet, including forefoot stiffness.
In a biological foot, the forefoot is dynamic, stiffening when lifting a heavy load and softening when performing a delicate task. Being able to mimic the biomechanics of the human foot is no easy task, but matching the right level of forefoot stiffness in prosthetic feet is crucial for gait and mobility of an LLA patient.
However, clinicians usually rely on manufacturer recommendations when it comes to determining the level of stiffness (“stiffness category”) for a particular patient. This is because there isn’t a lot of research out there on commercially-available feet; the effects of forefoot stiffness have only been studied using experimental prosthetic feet.
Seeking to fill in that gap, Halsne and Turner mechanically-tested forefoot stiffness in variations of five commercially available prosthetic foot types, representing a range of low- to high-activity feet. They observed inconsistencies across stiffness categories and foot sizes that clinicians may typically be unaware of when selecting a prosthetic foot for their patient based on manufacturer recommendations.
Halsne and Turner say the research underscores the importance of publishing standardized mechanical testing results for commercial prosthetic feet, in order to prescribe the optimal foot for a patient with LLA. They presented their research findings at the 2020 American Society of Biomechanics (ASB) conference in August.
Halsne and Morgenroth also recently published their findings on the effect of prosthetic foot stiffness on foot-ankle biomechanics and relative foot stiffness perception in people with below-knee amputation in the journal Clinical Biomechanics.
Bridging the Divide
Halsne and Turner each bring their unique backgrounds and expertise to the table. Halsne is a clinician by training; she also has an MS in Mechanical Engineering. Early on, her career was inspired by a speaker who described working with multidisciplinary teams treating victims of SE Asia landmines. It was a different approach to medicine; instead of trauma triage, the focus was on helping people get back to a meaningful life.
“It’s the marriage of engineering and working with people that I enjoy—that interplay is really rewarding,” she says.
Halsne practiced primarily during her time at the Rehabilitation Institute of Chicago (now called the Shirley Ryan AbilityLab). That organization’s combination of patient care and research inspired her to return to Seattle to pursue her PhD in Rehabilitation Science at the University of Washington.
Before Turner decided to switch to a career in medicine, she was a Boeing flight test engineer. As she progressed through her pre-med classes, she became involved in research, contacted CLiMB, and joined Dr. Morgenroth’s team alongside Halsne. She’s deferred her acceptance to med school in order to continue working with CLiMB.
“There’s a good balance between engineering and medicine in the work that we’re doing,” Turner says.
“Learning about the project—seeing if we can improve on the prosthetic foot prescription process—is really exciting. Even more, talking with patients in the lab, getting to know them, how amputation has affected them, how military life has affected them, has been really inspiring.”
It’s a Team Effort
Through the DoD funded study at CLiMB, Morgenroth, Halsne and Turner are making inroads into critically-needed research on the patient foot prescription process.
“It’s a team effort,” Halsne says, “and this project embodies how a collaboration between engineers, clinicians, and small businesses can really impact patients, improve lives, and address unmet needs in patient care.”
The team effort will continue on into the future. A new 4-year study led by PI Dr. Morgenroth involving Humotech, the VA Puget Sound Health Care System and the Minneapolis VA Health Care System (funded by OPORP) will focus on understanding the relationship between prosthetic foot mechanical properties and stability and falls-related outcomes in those with lower limb loss.
Stay tuned for research updates on this front!
(1) Molina, C.S., & Faulk, J. (2020). Lower Extremity Amputation. StatPearls Publishing. PMID: 31536201 http://creativecommons.org/licenses/by/4.0/