Anatomically Aligned Prosthetic Ankle with Passive Assist

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Solution Overview

Problem

Prosthetic ankles fail to anatomically align with users' natural physiology, leading to difficulties in walking, balance, and increased risk of falling, especially on uneven terrain or stairs, due to the lack of precise replication of natural ankle movement.

Innovation Solution

An anatomically aligned prosthetic ankle with a passive dorsi-flexion tendon assist mechanism, featuring a tibia section, talus, and prosthetic foot, where the talus and tibia are connected by a rotatable connector to mimic the user's natural ankle alignment, and a pneumatic or hydraulic spring assist mechanism to provide adjustable push-off force and resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a prosthetic ankle is designed with simplified structure, then device complexity is reduced, but anatomical alignment precision deteriorates

Engineering Contradiction:

Improveprosthetic ankle structureVSAvoidanatomical alignment precision

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The prosthetic ankle is divided into distinct anatomical segments (tibia section, talus, foot) connected by articulated joints. Each segment can be independently manufactured and assembled, allowing for precise anatomical alignment of individual components while maintaining overall structural manageability. The segmentation enables complex anatomical geometry to be achieved through simpler, modular parts.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A connector element (rod or pin) serves as an intermediary between the tibia section and talus, providing a precise mechanical interface that ensures accurate anatomical alignment. This intermediary component allows for controlled rotational and pivotal movements while maintaining the precise spatial relationship between bone segments, resolving the contradiction between structural simplicity and alignment precision.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If a prosthetic ankle lacks passive assist mechanism, then device complexity is reduced, but gait naturalness deteriorates

Engineering Contradiction:

Improveassist mechanism structureVSAvoidgait naturalness

Core Design Contradiction:

Device complexityVSEase of operation

Solution Approach 1:

The passive spring assist mechanism is designed to automatically provide dorsi-flexion assistance during the gait cycle without requiring external power sources or active control. The spring mechanism self-actuates based on the natural motion of the ankle, providing push-off force during the pre-swing phase and reducing plantarflexion resistance during stance phase, thereby enhancing gait naturalness through self-service mechanical assistance.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

A pneumatic or hydraulic spring assist mechanism is integrated into the prosthetic ankle to provide adjustable passive assistance. The pneumatic/hydraulic spring delivers controlled forces to assist dorsi-flexion during gait, mimicking the function of natural tendons and muscles. This allows for enhanced gait naturalness while keeping the overall device relatively simple, as the pneumatic/hydraulic system provides complex force characteristics through a single integrated component.

Inventive Principle:

Principle #29Pneumatics and hydraulics

3Manufacturing precision

If the talus is aligned in standard anatomical position, then anatomical alignment is improved, but adaptability to different users deteriorates

Engineering Contradiction:

Improveanatomical alignmentVSAvoiduser-specific alignment adjustment

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The connector is designed with adjustable alignment capabilities, allowing the talus to be positioned at different coronal and transverse angles relative to the tibia section. This dynamic adjustability enables the prosthetic ankle to be customized to match the specific anatomical variations of different users, while maintaining precise anatomical alignment when properly configured. The adjustable design resolves the contradiction by allowing the system to adapt between standard alignment and user-specific requirements.

Inventive Principle:

Principle #15Dynamics

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution enables a more natural gait and improved balance by closely matching the user's anatomical alignment, enhancing push-off force and stability during locomotion, thereby reducing the risk of falls and improving overall mobility.

Implementation Method 1

a pneumatic spring including a cylinder configured to produce a preset or adjustable force assist

Methodology Applied

Scientific EffectPneumatic spring:

Implementation Method 2

a pneumatic or hydraulic spring assist mechanism to provide adjustable push-off force and resistance

Methodology Applied

Scientific EffectHydraulic spring:

Data Source

PatentUS20220273468A1Anatomically Aligned Prosthetic Ankle

Publication Date: 2022.09.01 LOMA LINDA UNIVERSITY

AI summary

The present disclosure relates to an anatomically aligned prosthetic ankle with a passive assist and associated methods. The prosthetic ankle includes a talus movably coupled to a tibia section by a connector about which the talus is pivotal such so during locomotion by a user of the prosthetic ankle. The passive to assist provides a selected dorsi-flexion force to aid in the push-off or pre-swing phases of gait for the user.