Artificial Knee Joint Locking Mechanism for Stance Phase Stability
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Solution Overview
Problem
Current artificial knee joints face challenges in providing automatic and controlled locking mechanisms that ensure stability during weight-bearing phases while allowing unrestricted motion, often resulting in uncontrollable knee flexion and instability, especially when the user tries to fully extend the knee before loading weight.
Innovation Solution
An artificial joint design featuring a locking mechanism integral with the lower portion, which automatically engages and disengages based on the load's position relative to a control axis, utilizing a latch member and biasing means, such as a spring, to stabilize the joint and allow for voluntary flexion, with optional swing-phase control for enhanced mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If an automatic locking mechanism is used to provide stability during weight-bearing, then support and stability are improved, but the timing of locking may cause uncontrollable knee flexion and falling
Solution Approach 1:
The locking mechanism is designed to engage automatically when the knee approaches full extension during the stance phase, before weight loading occurs. This preliminary locking action prevents the timing problem where locking occurs after weight loading, which would cause uncontrollable flexion and falling.
2Reliability
If a manual disengagement mechanism is used for the locking mechanism, then the locking function is reliable, but the user requires a free hand to operate it which discourages therapeutic knee bending
Solution Approach 1:
The disengagement mechanism is designed to be automatically activated by the user's own knee flexion motion. When the user flexes the knee, the relative movement between the femoral component and tibial component automatically triggers the disengagement of the locking mechanism, eliminating the need for manual operation with a free hand and encouraging therapeutic knee bending.
3Stability of the object's composition
If the knee joint axis is placed behind the load bearing plane to improve stability, then support phase stability is improved, but ideal gait characteristics are not achieved
Solution Approach 1:
Instead of using a fixed mechanical alignment to provide stability, the invention employs a dynamic locking mechanism that activates automatically based on the knee's position and loading conditions. The locking mechanism engages when the knee approaches full extension during stance phase and disengages during swing phase, providing stability when needed while maintaining natural gait characteristics without requiring altered joint alignment.
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 solution provides automatic and reliable engagement and disengagement of the locking mechanism, ensuring improved stability and support during weight-bearing phases while allowing for natural and unrestricted motion, reducing manufacturing costs and design complexity, and enabling use in both prosthetic and orthotic applications.
Implementation Method 1
utilizing a latch member and biasing means, such as a spring, to stabilize the joint
Data Source
Figure 1a
Figure 1b
Figure 2a-b~5a-b
AI summary
An artificial joint including a main body and a lower portion adapted to pivotally engage the main body about a control axis while having a locking means that is integral with the lower portion. An upper portion adapted to pivotally engage the main body about a flexing axis and has an engagement means adapted to engage and disengage the locking means upon the pivoting rotation of the upper portion relative the main body. A biasing means is adapted to engage both the main body and the lower portion thereby biasing the locking means to engage the engagement means, and at least one stopping surface adapted to limit motion between the main body and the lower portion. The locking means is activated when a load is imposed on the artificial joint and passes through a line posterior to the control axis, and is desactivated when the load passes through a line anterior to the control axis.