Prosthetic Knee Locking Mechanism for Stable Extension
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Solution Overview
Problem
Existing prosthetic knee joints require multiple devices and costly modifications to achieve stable fixation in specific positions, particularly for new amputees who lack control over the knee joint.
Innovation Solution
A prosthetic joint design featuring a pawl with a locking mechanism and an adjustable spring system, allowing for secure fixation in the extension position, combined with an adjustable wedge and damping arrangement for smooth transition between extension and flexion positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a prosthetic knee joint is designed to allow free rotation during flexion and extension, then ease of operation is improved, but stability in fixed positions deteriorates
Solution Approach 1:
The prosthetic knee joint employs a dynamic locking mechanism with a pawl that can selectively engage with locking surfaces at specific positions (such as the extended position) while allowing free movement during flexion. This dynamic system transitions between locked and unlocked states based on the knee's position, providing stability when needed and freedom of movement when required.
Solution Approach 2:
The pawl acts as an intermediary element between the upper and lower parts of the prosthetic knee joint. It mediates the interaction by selectively engaging with locking surfaces to provide stability at specific positions while otherwise allowing smooth rotation, thus bridging the need for both stability and ease of operation.
2Adaptability or versatility
If multiple prosthetic knee joints are used to provide both free movement and fixed position capability, then functionality is improved, but device complexity and cost increase
Solution Approach 1:
The invention merges the functions of free movement and fixed position stability into a single integrated prosthetic knee joint. The locking mechanism with pawl and locking surfaces is incorporated directly into the joint structure, eliminating the need for separate devices or modifications. This combination provides both modes of operation within one unified system.
Solution Approach 2:
The prosthetic knee joint is designed with multi-functionality, serving both as a free-moving joint during normal operation and as a stable fixed-position device when the pawl engages with the locking surfaces. This universal design allows the same device to adapt to different user needs without requiring multiple specialized components.
3Stability of the object's composition
If a locking mechanism is added to fix the knee joint in certain positions, then stability is improved, but device complexity increases
Solution Approach 1:
The locking mechanism is designed to be self-actuating through the user's natural movement. As the knee approaches the extended position, the pawl automatically engages with the locking surfaces through the mechanical action of the joint itself, without requiring additional actuators, motors, or complex control systems. The spring-loaded pawl self-regulates its engagement based on the joint's position and applied forces.
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
Enables cost-effective, single-device functionality with stable fixation in the extended position, enhancing control for novice amputees and reducing the need for multiple prosthetic joints and modifications.
Implementation Method 1
an elastic element disposed in the lower part of the knee
Implementation Method 2
the spring preferably is a mechanical compression spring, its spring path and characteristic being adjustable by a screwing device
Implementation Method 3
the fixing means is a pawl hinged to the upper part of the knee, said pawl being engageable into a recess of the clamping member
Implementation Method 4
Between the clamping member and the lower part of the knee there is preferably provided an adjustable adjusting wedge
Implementation Method 5
the axis of rotation of the clamping member is eccentrically connected for rotation to at least one advance push-rod that is hinged to a spring piston of a spring carried in the lower part of the knee
Data Source
AI summary
The invention relates to a prosthetic joint which can be used as an artificial knee. Said prosthetic joint consists of a knee upper part (1), a knee lower part (2) and a fixing element (8) connecting said two lower parts. The knee upper part is rotationally arranged about the rotational axis (4) of the fixing element and rotation occurs counter to the force of an elastic element (17) which is arranged in knee lower part. Detachable fixing means (7), which are used to fix at least one rotational position, are provided between the knee upper part and the fixing element.