Flexible Orthopedic Hinge With Tunable Stiffness and Joint Guidance

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Solution Overview

Problem

Existing lightweight orthopedic device hinges lack adaptability to different activity levels, rigidity, strength, and motion control, and fail to dynamically conform to the user's limb shape, particularly between flexion and extension, while providing insufficient guidance and interference with other orthopedic device components.

Innovation Solution

A monolithic, flexible hinge body made from a polymeric material that extends continuously from one end to another, with an articulating section that can adjust its radius to fit the user's limb, incorporating a receptacle for an insert to modify stiffness and featuring a rib for reinforcement, allowing for angular control and minimal interference with natural leg motion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a robust hinge with multiple parts and structural elements is used, then joint guidance and movement facilitation are improved, but weight, cost, bulk, and complexity increase

Engineering Contradiction:
Improvejoint guidanceVSAvoidhinge weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent combines multiple hinge components (articulating section, reinforcement elements, strap mounting features) into a single monolithic polymeric structure. This integration eliminates the need for separate metal parts, fasteners, and moving components while maintaining joint guidance functionality, directly resolving the contradiction between reliability and weight.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent employs a flexible polymeric shell structure that provides hinge functionality without rigid metal components. The polymeric material forms a thin-walled but structurally sound articulating section that guides joint movement while being significantly lighter than traditional metal hinges, addressing the weight versus reliability trade-off.

Inventive Principle:
Principle #30Flexible shells and thin films

2Weight of moving object

If a lightweight hinge is used, then weight is reduced, but adaptability to different activity levels and rigidity control are insufficient

Engineering Contradiction:
Improvehinge weightVSAvoidrigidity adaptability
Core Design Contradiction:
Weight of moving objectVSAdaptability or versatility

Solution Approach 1:

The patent applies local quality by incorporating a receptacle for an insert at the articulating section, allowing localized stiffness modification without affecting the overall lightweight structure. The insert can be selectively added or removed to adjust rigidity according to different activity levels, enabling a single lightweight hinge design to adapt to varying support requirements.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The hinge design incorporates dynamic adaptability through the optional insert mechanism that allows users to adjust rigidity based on activity level. The polymeric material itself provides inherent flexibility that adapts to motion, and the insert system enables dynamic reconfiguration of structural properties without adding significant weight.

Inventive Principle:
Principle #15Dynamics

3Ease of operation

If a monolithic polymeric hinge body is used, then flexibility and fit are improved, but strength and stiffness may be reduced

Engineering Contradiction:
ImproveflexibilityVSAvoidhinge strength
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The patent employs composite material strategies by combining polymeric material with an optional rigid insert. The polymeric base provides flexibility and conformability, while the insert (when added) contributes strength and stiffness. This composite approach allows the hinge to achieve both flexibility for ease of operation and sufficient strength for structural support.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The monolithic polymeric hinge body incorporates curved and contoured surfaces that distribute stress more effectively than flat rigid structures. The articulated section features optimized curvature that enhances flexibility while maintaining structural integrity, allowing the hinge to bend repeatedly without failure despite being made from polymeric material.

Inventive Principle:
Principle #14Spheroidality (Curvature)

4Object-affected harmful factors

If the articulating section protrudes minimally, then interference with natural leg motion is reduced, but structural support may be compromised

Engineering Contradiction:
Improveinterference with leg motionVSAvoidstructural support
Core Design Contradiction:
Object-affected harmful factorsVSStrength

Solution Approach 1:

The patent segments the hinge structure into distinct functional zones: a minimal-protrusion articulating section for low interference, and integrated reinforcement elements (ridges, ribs) that provide structural support within the same compact form. The strap mounting features are also integrated into the articulating section rather than requiring separate protruding components, maintaining minimal profile while delivering adequate support.

Inventive Principle:
Principle #1Segmentation

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 hinge provides enhanced strength, stability, and dynamic accommodation to the user's limb dimensions, harmonizing support and flexibility while minimizing bulk and interference, thus offering improved fit and motion guidance without sacrificing any functional aspect.

Implementation Method 1

The hinge body is formed from a polymeric material and may be less hard than metal materials as found in conventional hinges... The single material structure may be compliant and adapted to flexibly bend not just within an angular range, but also transversely relative to a neutral longitudinal axis

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The articulating section has an adjustable floating center variable radius within the angular range... The articulating section preferably protrudes minimally from the orthopedic device, and occupies a minimal space over the user's leg... the articulating section minimizes substantial rigid structure along the medial and lateral sides

Methodology Applied
Scientific EffectVariable stiffness:

Data Source

PatentEP3664754B1Hinge for orthopedic device
Publication Date: 2021.09.29 OSSUR ICELAND EHF
  • EP3664754B1 patent drawingFigure 1
  • EP3664754B1 patent drawingFigure 2~3
  • EP3664754B1 patent drawingFigure 4~6B

AI summary

A hinge (102) has a hinge body (105) forming an articulating section (107) extending between a first end (109) and a second end (111) of the hinge (102). The articulating section (107) is adapted to bend from a neutral axis (N-N) when the first and second ends (109, 111) are parallel to an angular range in which the first end (109) is arranged among a plurality of angles within the angular range relative to the second end (111). The hinge body (105) may define a receptacle (142) along the articulating section (107), and an insert (126) may be provided for insertion into the receptacle (142). The insert (126) can modify the stiffness of the hinge (102) in the angular range and is arranged parallel to the neutral axis (N-N).