Knee Orthosis Asymmetric Force Distribution via Segmented Straps

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Solution Overview

Problem

Existing knee orthoses for treating genu varum and genu valgum deformities are bulky, uncomfortable, and have limited adjustability, as the tensioning elements are often complex and poorly positioned, leading to symmetrical force distribution and potential skin irritation.

Innovation Solution

The thigh and lower leg contact elements are connected to the knee element via tensioning elements in either the ventral or dorsal area, allowing for easier connection and adjustability, with the option to change the point of force application by shifting the elements, and using inelastic straps that can be variable in length to accommodate different activities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If tensioning elements are arranged in loops around the leg with symmetrical force distribution, then the force can be uniformly applied to the leg, but the positions of contact elements cannot be adjusted and the structure becomes complex and expensive

Engineering Contradiction:
Improvesymmetrical force distributionVSAvoidcomplex tensioning element guidance structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The tensioning element is divided into two separate segments: one connecting the thigh contact element to the knee element, and another connecting the lower leg contact element to the knee element. This segmentation allows independent positioning and adjustment of each contact element while maintaining force distribution, eliminating the need for complex loop structures.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The connection is moved from a three-dimensional loop structure around the leg to a two-dimensional arrangement where tensioning elements connect contact elements to the knee element in the frontal plane. This dimensional simplification reduces structural complexity while maintaining functional effectiveness.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Force

If tensioning elements are positioned in the ventral area to apply force, then force can be applied effectively, but skin irritation and discomfort occur during sitting or haptic activities

Engineering Contradiction:
Improveforce application effectivenessVSAvoidskin irritation and discomfort
Core Design Contradiction:
ForceVSObject-affected harmful factors

Solution Approach 1:

The knee element is designed with differentiated local qualities: a ventral side with higher rigidity for effective force transmission, and a dorsal side with lower rigidity or cushioning properties to reduce skin irritation and discomfort during sitting or haptic activities. This local differentiation allows the same component to satisfy both force application and comfort requirements.

Inventive Principle:
Principle #3Local quality

3Force

If rigid materials are used for thigh and lower leg braces to apply large forces, then sufficient force can be applied to treat deformities, but the orthosis becomes bulky and uncomfortable with low acceptance

Engineering Contradiction:
Improveforce magnitude applied to legVSAvoiduser comfort and acceptance
Core Design Contradiction:
ForceVSEase of operation

Solution Approach 1:

The thigh and lower leg contact elements are designed as flexible, thin components that conform to the leg contours, replacing bulky rigid braces. These flexible elements can still transmit sufficient corrective forces while providing comfort and aesthetic appeal, significantly improving user acceptance.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The orthosis utilizes composite material structures combining rigid components (for force transmission in the connecting element) with flexible, comfortable materials (for contact elements). This composite approach allows the system to deliver effective corrective forces while maintaining user comfort through soft, conforming contact surfaces.

Inventive Principle:
Principle #40Composite materials

Data Source

PatentEP3897476B1Knee orthosis
Publication Date: 2022.11.16 OTTOBOCK SE & CO KGAA
  • EP3897476B1 patent drawingFigure 1~2
  • EP3897476B1 patent drawingFigure 3~5

AI summary

The invention relates to a knee orthosis having a ventral and a dorsal portion, a thigh contact element (6), a lower leg contact element (8) and a knee element (14), at least one bracing element (12) and at least one inelastic strap (16), the thigh contact element (6) and the lower leg contact element (8) being connected to the knee element (14) in the ventral region by the at least one bracing element (12) and in the dorsal region by the at least one inelastic strap (16) or vice versa.