December 07, 2018 | Contact |

WillowWood Leads Government Grant to Develop Self-Adapting Prosthetic Ankle

WillowWood Leads Government Grant to Develop Self-Adapting Prosthetic Ankle

WillowWood has secured a $2 million Department of Defense Clinical Translational Research Award to develop and validate a self-adapting myoelectrically-controlled ankle utilizing continuously variable ankle stiffness. The research grant will explore the myoelectric collection and application of lower limb muscle contracture data that will be used to control the prosthetic device while determining the appropriate ankle stiffness for a user’s activity in real-time.

A human’s muscles stretch and contract to store and return energy as well as continuously change the stiffness of the ankle depending upon terrain, speed, and intended activity. Existing prosthetic feet are capable of storing and returning energy to the user but do not offer adjustable stiffness levels for different tasks. Due to the complexity of ankle biomechanics, today’s prosthetic feet are unable to automatically adapt stiffness levels. WillowWood is the leader in a Department of Defense Peer-Reviewed Orthopaedic Research Program, Clinical Translational Research Award to address this performance gap. Together with its grant partners, Shirley Ryan AbilityLab (formerly Rehabilitation Institute of Chicago), the University of Michigan and the Louis Stokes Cleveland VA Medical Center, WillowWood aims to develop and validate a variable stiffness prosthetic ankle design that includes myoelectric pattern recognition to improve the function of the prosthetic device.

The prosthetic device, originally conceived at the Center for Bionic Medicine at Shirley Ryan AbilityLab, will be designed to imitate a person’s natural ankle movement during stance phase while allowing the ankle to change the stiffness level during swing phase in order to accommodate different activities. To collect the necessary myoelectric data during the research project, clinical test participants will wear prosthetic liners with embedded electrodes which will capture muscle contracture signals as test participants complete various mobility tasks. The user’s intentions, signaled by the myoelectric pattern, will aid in the control of the ankle.

“There is a significant need to develop prosthetic technologies that can more accurately provide the varying mechanics exhibited by the human foot and ankle, which we believe will address mobility challenges faced by amputees,” stated Jim Colvin, WillowWood’s director of research and technology and principal investigator for the grant. “Amputees will experience numerous benefits from this new design including greater preservation of energy rather than removal of substantial energy due to damping as in current microprocessor controlled prosthetic feet.”

As the second year of the study begins, the product’s initial design and control system has been refined with additional sensor integration. Clinical testing is scheduled to begin in 2019 for a duration of 18 months. The research award is slated for completion by the end of 2020.

Advancements in personal and vehicle armor as well as overall improvements in medical care have increased the U.S. military’s combat injury survival rate. A 2012 article in the Journal of Military and Veteran’s Health estimates over 1,200 service personnel have survived after sustaining one or more limb amputations due to combat injuries. New prosthetic technology, such as that being developed in this research award, will allow service personnel, veterans, and civilians with limb loss to have highly active lifestyles and may also allow more military personnel to return to active duty status and continue their careers in the military.

About WillowWood

WillowWood is a fourth-generation, family owned company and an industry leader in the design, manufacturing, and distribution of prosthetic products, including the Alpha® family of liners and the OMEGA® CAD system. Headquartered in Mt. Sterling, Ohio, WillowWood also has a location in Salt Lake City, Utah, and a network of over 20 global distribution partners. For more information about WillowWood and its products, visit

About Shirley Ryan AbilityLab

The Shirley Ryan AbilityLab, formerly the Rehabilitation Institute of Chicago (RIC), is the global leader in physical medicine and rehabilitation for adults and children with the most severe, complex conditions — from traumatic brain and spinal cord injury to stroke, amputation and cancer-related impairment. The organization expands and accelerates leadership in the field that began at RIC in 1953. The quality of its care and research has led to the designation of “No. 1 Rehabilitation Hospital in America” by U.S. News & World Report every year since 1991. Upon opening in March 2017, the $550 million, 1.2-million-square-foot Shirley Ryan AbilityLab became the first-ever “translational” research hospital in which clinicians, scientists, innovators and technologists work together in the same space, surrounding patients, discovering new approaches and applying (or “translating”) research real time. This unique model enables patients to have 24/7 access to the brightest minds, the latest research, and the best opportunity for recovery. Recent honors for the organization include a Chicago Innovation Award and the Modern Healthcare Design Gold Award. The Shirley Ryan AbilityLab is a 501 (c)(3) nonprofit organization. For more information, go to

About the Louis Stokes Cleveland VA Medical Center

The Louis Stokes Cleveland VA Medical center is part of the Northeast Ohio VA Healthcare System. This healthcare system provides timely, high quality healthcare to more than 8,100 veterans daily through its inpatient and outpatient health care services at 18 locations of care across Northeast Ohio.

About the University of Michigan

The University of Michigan College of Engineering is one of the nation’s top engineering schools. It is home to 11 top-ranked departments, and its research budget is one of the largest of any public university. Michigan Engineering’s mission is to provide scientific and technological leadership, and to improve the quality of life around the world by developing intellectually curious and socially conscious minds, creating collaborative solutions to societal problems, and promoting an inclusive and innovative community of service for the common good. An alumni base of 80,000 spans the globe.

U.S. Army Medical Research Acquisition Activity

The U.S. Army Medical Research Acquisition Activity, 820 Chandler Street, Fort Detrick MD 21702-5014 is the awarding and administering acquisition office. This work was supported by the Office of the Assistant Secretary of Defense for Health Affairs, through the Peer Reviewed Orthopaedic Research Program under Award No. W81XWH-17-1-0704. Opinions, interpretations, conclusions and recommendations are those of the author and are not necessarily endorsed by the Department of Defense.