NextStep Robotics seeks FDA authorization to use its lower body exoskeleton for more than just exercise

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A Baltimore startup could help stroke survivors improve how they move, even months after rehab ends.

NextStep Robotics’ AMBLE device targets foot drop, a condition that limits someone’s ability to lift the front of the foot while walking. The assistive tech is gathering another FDA authorization, with affordability front of mind, according to CEO Bradley Hennessie.

“Most small community-based clinics can’t afford a $120,000 exoskeleton system,” Hennessie told Technical.ly.

Most rehabilitation happens in lower-budget clinics rather than resource-rich institutions, Hennessie said. AMBLE charges clinics a subscription fee for the device and software package, instead of an upfront fee, but costs can vary, Hennessie said. 

The device is worn on the knee, paired with a sensor on the shoe that tracks a patient’s steps in real time. It helps lift the foot with robotic assistance, adjusting as the patient gets stronger. 

AMBLE is currently FDA-cleared as an exercise device, which allows NextStep to sell it to clinics for use during gait therapy. But Hennessie said he hopes the next level of FDA clearance, called a De Novo submission, will expand its use.

The team completed its three-year, National Institutes of Health–funded clinical trials in 2024, after the onset of the COVID-19 pandemic delayed the study’s start. Conducted at the University of Maryland, Baltimore, the trials found that patients continued to improve in key walking measures for months after training ended, including follow-ups more than a year later.

That outcome is significant, Hennessie said, because patients are typically told that functional recovery plateaus about six months after a stroke, with limited expectations for further improvement. 

“Our clinical trial results show that it has much more benefit than just being helpful during exercise,” Hennessie said.

Potential for spine, arm assistive tech 

While AMBLE was initially developed to treat foot drop, the company sees broader potential for the technology. 

Most recently, NextStep received approval from the Kennedy Krieger Institute to test the device with spinal cord injury patients. The team is planning to gather preliminary data from a small pool of patients before conducting a larger study, Hennessie said. 

NextStep is also developing other devices. 

The company is creating a standalone version of its shoe-based sensor that can track how someone walks without the exoskeleton, according to Hennessie. The sensor is designed to monitor changes in walking patterns and, over time, help identify patients at risk of falling. 

NextStep is also developing an upper-extremity device, for the arm or hand, that uses the same “assist-as-needed” approach as AMBLE. 

The company is finalizing its shoe sensor product. An initial prototype of its upper extremity device was developed and tested as a part of a Ph.D. project at the University of Maryland, Baltimore. 

“We make sure that,” Hennessie said, “the user is making as much of the motion on their own [as possible].”