Session: Research Posters

Paper Number: 171240

User-Tuned Mechanical Intelligence: A Passive Ankle-Foot Orthosis With Interchangeable Reconfigurable Compliant Joints 

Foot drop is a neuromuscular impairment that limits a patient’s ability to dorsiflex the ankle during the swing phase of gait, resulting in reduced toe clearance and a significantly increased risk of falls. Individuals with foot drop often adopt compensatory strategies such as exaggerated hip and knee flexion (steppage gait), leg circumduction, or contralateral vaulting to avoid toe drag. These compensations increase metabolic cost, redistribute joint loading proximally, and reduce both walking efficiency and postural stability. Ankle-foot orthoses (AFOs) serve as the primary clinical intervention for managing foot drop. Their primary function is to assist dorsiflexion during swing and provide support during stance. However, most commercially available AFOs offer static, one-size-fits-all solutions that do not reflect the complex biomechanical needs of individual users or adapt to different gait impairments and rehabilitation stages.This study presents the development of a modular passive ankle-foot orthosis (pAFO) designed to accommodate a wide range of foot drop gait presentations, which may result from neurological, muscular, or orthopedic conditions. These varying etiologies influence different phases of the gait cycle, necessitating a device that can adapt its mechanical response accordingly. We address this need by integrating mechanical intelligence into the orthosis through a fully passive yet structurally adaptive architecture. Rather than relying on sensors or powered actuators, the system leverages geometry, material compliance, and modular reconfiguration. The orthosis includes a Reconfigurable Compliant Joint (RCJ), which replaces conventional hinge joints with geometry-based elastic components capable of storing and releasing mechanical energy. The RCJ generates passive torque about the ankle’s sagittal axis by the input of the user’s body weight and joint rotation, and can be changed to tune the stiffness and motion characteristics of the device to their specific needs. The orthosis features an external shoe-mounting system compatible with a variety of footwear types, foot lengths, and heel loading points. Adjustable medial and lateral support arms enable changes in both height and anatomical positioning of frontal plane stabilization thereby allowing for clinician-specific configurations and adaptation to patient needs. .To evaluate the mechanical behavior of the pAFO, we developed a benchtop gait simulation rig with six-degree-of-freedom (6-DOF) sensors to capture ankle joint kinematics and loading patterns across simulated gait phases. Preliminary tests demonstrate that different RCJ configurations produce distinct torque profiles that aid dorsiflexion and improve foot clearance. These findings support the potential of this passive device to provide tailored mechanical correction across a variety of drop foot conditions, offering a customizable, scalable alternative to traditional AFO designs.

Presenting Author: Vanessa Young Kennesaw State University

Presenting Author Biography: Interdisciplinary Engineering PhD Student and Graduate Researcher at the Southern Polytechnic Compliant Mechanisms (SPCM) Lab, Kennesaw State University

Authors:

Vanessa Young Kennesaw State University
Jamie Assaf Kennesaw State University
Sabrina Scarpinato Kennesaw State University
Ayse Tekes Kennesaw State University