Multi-axis Ankle Prosthesis with Adjustable Joint Axes
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Solution Overview
Problem
Current ankle prostheses often employ single or two-axis fixation designs, leading to unnatural gait, discomfort, and low adaptability to different environments and terrains due to their kinematic mechanical properties differing from those of healthy ankles.
Innovation Solution
A small-size multi-axis ankle prosthesis with a biomechanically designed structure that allows individual adjustment of joint axis angles, incorporating a lower part, joint axis, upper part, springs, and oil-free bushings, enabling precise angle adjustments to mimic human ankle movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single axis or two axes fixation design is adopted, then the structure is simple, but the kinematic mechanical properties differ from healthy ankles, causing unnatural gait and low adaptability
Solution Approach 1:
The ankle prosthesis is divided into multiple independent rotational axes (first rotational axis for talocrural joint, second rotational axis for subtalar joint) that can move relative to each other. This segmentation allows each axis to independently replicate specific ankle movements, achieving multi-axis kinematic properties that closely match healthy human ankle mechanics while maintaining modular structural simplicity
Solution Approach 2:
The prosthesis employs dynamic rotational joints that allow real-time adjustment of movement angles and axes. The first and second rotational axes enable dynamic adaptation to different terrains and walking conditions by adjusting the orientation and range of motion, transforming a static simple structure into a dynamic system that mimics healthy ankle adaptability
2Ease of manufacture
If fixed angle design is used, then manufacturing is easy, but wearers cannot adjust to different terrains and environments
Solution Approach 1:
The prosthesis incorporates adjustable rotational axes with movable connecting blocks and positioning holes that allow users to adjust the angle and orientation of the first and second rotational axes according to different terrains and personal needs. This dynamic adjustment capability is achieved through simple mechanical structures including arc-shaped slots, positioning holes, and locking mechanisms that maintain ease of manufacture while providing versatile adaptability
Solution Approach 2:
The design allows changing of geometric parameters (angles, positions) of the rotational axes through adjustable connecting blocks and positioning mechanisms. Users can modify the orientation angles of the first and second rotational axes to match different walking conditions, transforming a fixed-parameter design into a variable-parameter system that maintains manufacturing simplicity
3Adaptability or versatility
If multi-axis structure is implemented, then movement coordination and adaptability improve, but device complexity increases
Solution Approach 1:
The complex multi-axis movement is segmented into two primary rotational degrees of freedom (first rotational axis for dorsiflexion/plantarflexion, second rotational axis for inversion/eversion). This segmentation simplifies the overall structure by breaking down complex multi-axis kinematics into manageable independent rotational joints, reducing structural complexity while maintaining movement coordination
Solution Approach 2:
The prosthesis merges the talocrural joint and subtalar joint functions into a single integrated structure with two rotational axes. By combining these joint functions into one unified prosthesis unit rather than separate components, the design achieves multi-axis movement coordination while avoiding the complexity of multiple separate mechanical assemblies
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 prosthesis improves movement coordination and adaptability, reduces energy consumption, and enhances wearing comfort by allowing adjustable angles, providing a more natural gait and better environmental adaptability.
Implementation Method 1
a first spring 1, a second spring 2, a third spring 3 and a fourth spring 4
Implementation Method 2
an oil-free bushing group 21
Data Source
AI summary
A small-size multi-axis ankle joint prosthesis is provided. Two ends of each of four springs are fixedly connected with two spring seats at an upper part and at the lower part respectively. The joint axes are positioned in a space surrounded by the lower part, the four springs and the upper part. Front and rear perforated blocks in the joint axes are respectively in bolted connection with a fifth arc hole pair g and a sixth arc hole pair h of a second arc plate in the upper part. Left and right perforated blocks in the joint axes are respectively in bolted connection with a second arc hole pair e and a third arc hole pair f of the first arc plate in the lower part.