Knee Joint Orthosis Hinge with Stationary Rotation Center
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Solution Overview
Problem
Existing knee joint orthoses, prostheses, and braces fail to accurately replicate the kinematics of the natural human knee, leading to unpleasant stresses and impaired mobility due to inadequate recreation of the knee's rotational center.
Innovation Solution
A hinge mechanism with overlapping hinge brackets that allow a combined rolling and sliding movement, featuring curved cut-outs and guide elements to maintain a stationary center of rotation up to 25°, transitioning into a radial displacement, and incorporating adjustable features for varus/valgus positioning and length adjustment to mimic natural knee movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed hinge connection is used between upper leg and lower leg components, then the structure is simple and stable, but it cannot accurately replicate the kinematics of the natural knee joint
Solution Approach 1:
The hinge connection transitions from a fixed, static joint to a dynamic system where the center of rotation can move along a predetermined trajectory. The guide element moves within the curved guide opening, allowing the instantaneous center of rotation to change position dynamically during knee flexion and extension, thereby replicating natural knee kinematics while maintaining structural simplicity.
Solution Approach 2:
A guide element acting as an intermediary component is introduced between the upper leg component and lower leg component. This guide element interacts with the curved guide opening to control and constrain the movement of the center of rotation along a specific path, enabling accurate kinematics reproduction without requiring complex multi-component mechanisms.
2Stability of the object's composition
If the center of rotation is kept stationary for small angles (0-25°), then rotational stability is improved, but the ability to accommodate larger bending ranges is limited
Solution Approach 1:
The hinge system implements a dynamic center of rotation that remains stationary only within the small angle range (0-25°) to maintain rotational stability, then transitions to moving along a curved trajectory for larger bending angles. This dynamic behavior allows the system to optimize for stability when needed while accommodating the full physiological range of knee motion up to 135 degrees.
Solution Approach 2:
The movement range is segmented into two distinct phases: a first phase (0-25°) where the center of rotation remains stationary to provide rotational stability, and a second phase (>25°) where the center of rotation moves along a curved trajectory to accommodate larger bending angles. This segmentation allows optimization for different functional requirements at different stages of knee motion.
3Reliability
If curved guide openings are used to enable rolling and sliding movement, then kinematics accuracy is improved, but manufacturing complexity increases
Solution Approach 1:
The guide element serves as an intermediary that simplifies manufacturing. Instead of creating complex curved openings directly in the hinge brackets, the guide element with its curved surface interacts with simpler openings, thereby achieving the desired rolling and sliding movement with more manufacturable components.
Data Source
AI summary
A hinge for knee joint orthoses, prostheses and/or braces includes first and second hinge brackets overlappingly connected to each other at their ends so that with increasing angle therebetween, a combined rolling and sliding movement is effected in a plane defined by the two hinge brackets. Curves and guide elements at the overlapping ends of the hinge brackets interact such that with increasing angle therebetween, a combined rolling and sliding movement of the second hinge bracket is effected in the plane defined by the two hinge brackets in a direction which leads substantially radial to the axis of the first hinge bracket into the quadrant enclosed between the two hinge brackets, wherein the center of rotation of the two hinge brackets remains substantially stationary for an angle between the hinge brackets of between 0 and 25°.