Artificial Knee Joint Projection Recess Stability
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Solution Overview
Problem
Existing artificial knee joints require additional stabilization means due to the incongruence of osseous partners, often leading to cruciate ligament tears from uncontrolled twisting movements, necessitating surgical replacement and anchoring procedures.
Innovation Solution
An artificial joint design that incorporates a projection and recess system allowing for controlled posterior sliding and blocking, mimicking the function of both cruciate ligaments, thereby providing anatomical stability without the need for additional auxiliary means, with adjustable and variable displacement limits based on flexion angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional artificial knee joint design is used with incongruent osseous partners, then the joint structure is simpler, but additional stabilization means are required and cruciate ligament tears occur from uncontrolled twisting movements
Solution Approach 1:
The patent merges the stabilizing function into the joint geometry itself through the shaping formed by the projection and recess. The projection on one joint part fits into the recess of the other joint part, creating an integrated stabilizing structure that eliminates the need for separate stabilizing components while preventing uncontrolled twisting movements
Solution Approach 2:
The shaping formed by the projection and recess acts as an intermediary structure that mediates between the incongruent osseous partners. This intermediate geometric feature provides the necessary stability and controls movement without requiring additional ligamentous or mechanical stabilizers
2Reliability
If cruciate ligament replacement surgery is performed with tendon anchoring, then joint stability is restored, but surgical trauma and procedural complexity increase
Solution Approach 1:
The patent extracts the stabilizing function from the biological ligamentous apparatus and implements it through the artificial joint's geometric shaping. By removing the dependency on cruciate ligaments and their surgical replacement, the design eliminates the associated surgical trauma and complex anchoring procedures while maintaining joint stability
Solution Approach 2:
The shaping formed by the projection and recess copies the stabilizing function of the natural cruciate ligaments through geometric constraints rather than biological tissue. This functional copying allows the joint to achieve stability without requiring ligament replacement surgery
3Ease of manufacture
If fixed stop position is used in artificial joint, then manufacturing is simpler, but adaptability to different patients and conditions is reduced
Solution Approach 1:
The patent implements a dynamic stop mechanism where the position of the stop is not fixed but varies with the flexion angle of the joint. As the joint flexes, the projection moves along the recess, allowing the stop position to adapt automatically to different flexion angles and patient-specific requirements, thereby combining manufacturing simplicity with clinical adaptability
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 design ensures stable joint movement by limiting posterior displacement and preventing undesired sliding, allowing for natural ligamentous apparatus functionality replacement, reducing the need for additional stabilizers and minimizing trauma during surgical procedures.
Implementation Method 1
The artificial joint has a shaping which is formed by a projection associated with the first joint part and a recess associated with the second joint part and which determines the relative position of the two joint parts in the transverse plane and also forms a stop for a sliding movement of the joint parts relative to one another
Implementation Method 2
the functional surfaces being pivotable about one pivot axis in each case, and being formed in such a way that upon extension/flexion of the joint a combination of a rolling and a sliding movement occurs
Implementation Method 3
a combination of a rolling and a sliding movement occurs
Data Source
AI summary
An artificial joint as an endoprosthesis for a human joint, including a first joint part having two first functional surfaces, a second joint part having two second functional surfaces, the two first and second functional surfaces of each joint part being convex-concave, concave-convex, or convex-convex in a proximal-distal direction, a projection associated with the first joint part; and a recess associated with the second joint part. The recess is configured to engage with the projection so as to determine a relative position of the first and second joint parts in a transverse plane of the joint and to form a stop for a sliding movement of the first and second joint parts relative to each other. The two first functional surfaces are pivotable about a pivot axis with respect to the second functional surfaces.