Introduction

Researchers at the Defense Health Agency (DHA) and the Henry M. Jackson Foundation (HJF) have developed a lower extremity exoskeleton to assist individuals with bone stress injuries, specifically tibial stress fractures. Conventional management of tibial stress fractures requires up to 18 weeks of rest and activity modification, which is disruptive for Military trainees and athletes. The RESTORE aims to reduce stress on the tibia during load-bearing activities and enable faster rehabilitation while allowing continued mobility.

Applications and Advantages:

• Reduces tibial stress during walking, running, and other load-bearing activities.
• Enables rapid return to high activity levels, shortening rehabilitation time.
• Modular and adjustable design fits multiple users without requiring customization, enabling rapid interventions.
• Simple mechanical design without hinges, springs, or elastic components reduces maintenance complexity.

Description of the Invention

The invention comprises three primary components: a proximal cuff that wraps around the calf beneath the knee, a height adjustable posterior strut, and a rigid footplate that interfaces with footwear. The posterior strut extends from the back of the proximal cuff to the rear of the footplate, providing structural support and energy storage/return during gait phases. The proximal cuff includes an anterior portion of both flexible and semi-rigid materials and a semi-rigid posterior portion, secured by hook-and-loop straps for adjustability across different calf sizes. Materials used include carbon fiber, fiberglass, aluminum, and thermoformable plastics. Unlike pneumatic casts that immobilize the user, or traditional exoskeletons designed for severe limb salvage, which require hours of clinical and technical fabrication time, this exoskeleton is novel in its modular, adjustable design. The RESTORE enables tibial offloading during active use to facilitate both healing and continued mobility. Its non-obviousness lies in combining modular adjustability, advanced materials, and functional integration with footwear to address tibial stress fractures effectively.

Figure:

FIG. 1A: Anterior medial view of the orthosis showing the proximal cuff, posterior strut, and footplate.
FIG. 1B: Posterior view highlighting the posterior strut extending from the cuff to the footplate.

Inventors:

• W. Lee Childers (DHA)
• William B. Johnson (DHA)
• Ciera A. Price (HJF)
• Emily M. McCain (HJF)

Innovation Status:

The prototype was developed through iterative testing with a robotic surrogate and a validation study of the prototype has been published: McGrath, R. L., Price, C. A., Johnson, W. B., & Childers, W. L. (2024). Advancing Exoskeleton Development: Validation of a Robotic Surrogate to Measure Tibial Strain. Bioengineering, 11(5), 490. https://doi.org/10.3390/bioengineering11050490 .

A functional prototype is now being pilot tested in healthy participants. Preliminary pilot data suggests that the prototype reduces tibial load relative to no device during running and walking. The next steps are to collect data on an additional 12 participants to complete the pilot testing and to further optimize materials, trim lines, and adjustable features for the next iteration of the prototype.

Intellectual Property Status:

A PCT patent application has been filed.