Multi-axis flexible monolithic prosthetic foot for lower limb rehabilitation.

Abstract

The invention presents a multi-axis composite prosthetic foot based on a monolithic flexible mechanism, applicable to the rehabilitation of lower limb disabilities. The prosthetic foot comprises a concentric multi-ring ankle region, an elastic heel region, a dorsifoot region, a plantar region, and a forefoot / toe region, fabricated monolithicly from elastic composite or fiber-reinforced polymer material. Functional movements of the prosthetic foot are generated through controlled elastic deformation of the flexible mechanism in place of traditional mechanical joints. The multi-axis structure allows for simultaneous multi-degree-of-freedom of movement such as plantar flexion, dorsiflexion, inversion, lateral flexion, torsional movement, and movements adapting to uneven terrain. The concentric elastic rings and serpentine-compliant elements act as equivalent elastic joints, allowing for vibration absorption, shock absorption, and load redistribution during the phases of the gait cycle.The heel and forefoot regions are designed as nonlinear structures capable of storing and returning elastic energy during walking, thereby supporting the propulsion phase and improving gait naturalness. The monolithic structure, without separate mechanical joints, reduces friction, wear, fatigue life, and maintenance requirements during use. The invention can be fabricated using methods such as 3D printing, composite molding, or other fabrication technologies, allowing for easy optimization of geometry and personalization of elastic properties for each user. The proposed solution offers high efficiency in terms of biomechanics, energy return, walking stability, and expands the application possibilities of soft structures and advanced composite materials in the field of lower limb rehabilitation.