Hydraulic Prosthetic Feet: Task-Specific Biomechanical and User‑reported Effects in Individuals with Transtibial Amputation

Background:

Hydraulic prosthetic feet are intended to improve functional adaptability during ambulation, particularly on uneven and inclined surfaces. Although previous studies have reported benefits in clinically relevant outcomes such as safety and mobility, their specific effects relative to conventional energy storage and return (ESR) feet remain insufficiently characterized.

Objective:

To compare the biomechanical and user‑reported effects of two hydraulic prosthetic feet with a conventional ESR foot during walking and standing tasks in individuals with transtibial amputation.

Study Design:

Exploratory cross‑over study.

Methods:

Ten experienced transtibial prosthesis users completed testing with three prosthetic feet: a nonhydraulic ESR reference foot and two hydraulic feet differing in ankle range of motion (ROM) and foot design. Participants performed walking and standing tasks. Outcome measures included spatiotemporal gait parameters, minimum toe clearance, ankle kinematics and power, ground reaction forces, joint moments, and participant-reported socket comfort and perceived physical effort.

Results:

Both hydraulic feet consistently increased prosthetic-side minimum toe clearance across all walking tasks, primarily due to a more dorsiflexed ankle orientation during swing. Across biomechanical and subjective outcomes, effects were more pronounced during nonlevel tasks.

Hydraulic feet altered ankle function, characterized by adapted ankle motion and increased energy absorption. No consistent or systematic foot‑dependent differences were observed in fundamental spatiotemporal gait metrics. Despite differences in available hydraulic ROM, both hydraulic feet produced largely similar biomechanical outcomes across walking tasks.

During standing on slopes, load distribution between limbs was more symmetrical with hydraulic feet during uphill standing. Participant‑reported socket comfort and perceived physical effort improved during ramp walking and standing, with stronger and more consistent effects observed for the hydraulic foot with greater ROM.

Conclusions:

The effects of hydraulic prosthetic feet were task-specific, with the greatest biomechanical and subjective benefits observed during walking and standing tasks requiring adaptation to nonlevel surfaces. Despite differences in available hydraulic ROM, both hydraulic feet produced largely similar functional outcomes.

Clinical Relevance Statement:

Improved toe clearance, slope adaptation, and perceived comfort associated with hydraulic prosthetic feet may reduce tripping risk and physical effort during everyday ambulation on nonlevel surfaces. These findings support the consideration of hydraulic ankle‑foot systems in the prosthetic prescription for active individuals with transtibial amputation. ( J Prosthet Orthot. 2026;XX:XX–XX).