Researchers Explore AFOs for Treating Achilles Tendinopathy

In Elisa Arch’s Orthotics and Prosthetics for Enhanced Mobility Lab, at the University of Delaware (UD), Newark, students are exploring how a specially designed ankle-foot orthosis (AFO) from medical device start-up Biomotum, Portland, Oregon, can help people with Achilles tendinopathy (AT) regain mobility. The device, used alongside sensors, is tested on a split-belt treadmill, allowing students to collect precise data on tendon load while experimenting with stiffness adjustments that could enhance rehabilitation outcomes. Her work has received seed funding from UD’s Big Ideas Challenge.

According to Arch, associate professor of kinesiology and applied physiology in UD’s College of Health Sciences, “AFOs have never been tested in people with Achilles tendinopathy.”

“AFOs are like a spring, and the tendon is like a giant rubber band,” explained Arch. “As the ankle tries to bend, the rubber band controls how much it bends. The AFO provides resistance to bending, which is what your calf muscles and Achilles tendon also do.”

The Biomotum device allows separate adjustment of dorsiflexion and plantarflexion stiffness, which is key for AT rehabilitation and may help avoid adverse side effects. Arch hypothesizes that higher stiffness provides greater tendon offloading and that gradually reducing stiffness as the tendon heals could support recovery. Using stiffness to assist an injured joint is a relatively new concept. Arch notes in the clinic that an AFO’s stiffness is not traditionally quantified.

“If we can prove feasibility in concept, which the [National Institute of Health] wants to see, we could get larger awards,” said Arch, who believes her research may be of interest to the US Department of Defense. “AT is a common overuse injury in active service members. If we can put an AFO on them and have them up and active earlier in rehab, they can return to duty sooner.”