Knee Orthosis Helicoidal Axis Hinge Design
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Solution Overview
Problem
Existing knee orthoses do not fully account for the natural movement of the knee, particularly in the sagittal, frontal, and transverse planes, limiting their effectiveness in stabilizing and guiding the knee joint after ligament instabilities, osteoarthritis, or surgeries.
Innovation Solution
A knee orthosis with a helicoidal axis mechanism, comprising a femoral section and a tibial section that pivot relative to each other via medial and lateral hinges with superposed spherical shells, allowing movement in six degrees of freedom, and customizable to conform to individual anatomy using 3D modeling and additive manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If existing orthoses are designed to account for roll back femoral action, then sagittal plane movement is improved, but natural movement in all three planes is not fully accounted for
Solution Approach 1:
The patent transitions from a single-plane (sagittal) hinge mechanism to a multi-plane helicoidal axis mechanism that enables movement in sagittal, frontal, and transverse planes simultaneously. The helicoidal axis allows the orthosis to replicate the complex three-dimensional motion patterns of the natural knee joint, addressing the limitation of existing single-plane designs.
Solution Approach 2:
The patent employs a dynamic helicoidal axis that can adapt its orientation and movement characteristics based on the knee's position and loading conditions. This dynamic capability allows the orthosis to accommodate varying movement requirements across different planes of motion, rather than being constrained to a fixed single-plane mechanism.
2Device complexity
If a single hinge axis is used, then device complexity is reduced, but the ability to guide natural knee movement in six degrees of freedom is limited
Solution Approach 1:
The patent divides the knee joint movement into two separate hinge mechanisms (medial and lateral hinges) that work in conjunction with each other. Each hinge is responsible for specific movement components, and their combined action produces the full six degrees of freedom required for natural knee motion, distributing the complexity across multiple specialized components rather than requiring a single complex mechanism.
Solution Approach 2:
The patent employs spherical shell structures in the hinge design that allow for multi-directional rotation and movement. The spherical geometry inherently provides capability for motion in multiple planes and degrees of freedom, enabling the hinges to accommodate the complex three-dimensional motion patterns of the natural knee joint while maintaining a relatively simple structural form.
3Ease of manufacture
If existing orthoses are designed for general use, then ease of manufacture is improved, but customization to individual anatomy is limited
Solution Approach 1:
The patent enables customization of specific local parameters such as hinge position, axis orientation, and shell geometry to match individual patient anatomy while maintaining the overall structural design and manufacturing process. This allows standardization of the basic orthosis components for ease of manufacture, with customization applied only to the specific geometric parameters that affect fit and function for each patient.
Solution Approach 2:
The patent utilizes adjustable and variable geometric parameters in the hinge and shell design that can be modified to accommodate different anatomical configurations. By making key dimensions and orientations variable rather than fixed, the orthosis can be adapted to individual patient anatomy while using the same fundamental manufacturing processes and component designs.
Data Source
AI summary
A knee orthosis is provided. In described embodiments, the knee orthosis is designed to follow a natural movement of a wearer's knee along an asymmetric helicoidal axis of rotation. In some embodiments, the knee orthosis has hinges with shells having displacing geometric centers which do not coincide. In some embodiments, the knee orthosis is made of femoral and tibial hinges manufactured as single integral pieces. In some embodiments, the orthosis is configured to realign the wearer's knee in a frontal plane. Corresponding methods for designing and manufacturing a custom knee orthosis are also provided.