Artificial Knee Post Inclined Surface Dislocation Prevention
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Solution Overview
Problem
Conventional artificial knee joints face challenges in preventing dislocation of the thighbone coupling member during knee movement, often requiring increased wear on the bearing member or more bone removal during surgery, which complicates dislocation prevention and restoration.
Innovation Solution
The design features a post with an upper surface inclined at a predetermined angle and an upper curved surface extending posteriorly from the upper surface, with a lower curved surface having a larger radius of curvature, allowing the thighbone coupling member to naturally descend and prevent dislocation without increasing the amount of bone to be cut or wear on the bearing member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the height of the post is increased to increase jump distance and prevent dislocation, then dislocation prevention is improved, but wear of the bearing member increases and amount of bone to be cut increases
Solution Approach 1:
The patent changes the geometric parameters of the post by inclining the upper surface at a predetermined angle (e.g., 5-15 degrees) and designing specific curvature radii for the upper and lower curved surfaces. This parameter optimization allows the post to achieve adequate jump distance for dislocation prevention while maintaining reasonable contact area with the cam to reduce bearing member wear, avoiding the need to simply increase post height.
Solution Approach 2:
The patent applies curvature to the post surface by designing an upper curved surface extending posteriorly from the upper surface and a lower curved surface, both with specific radius of curvature values. These curved surfaces enable smooth cam motion and distribute contact stresses, preventing dislocation through geometric constraint rather than increased height, thereby reducing wear on the bearing member.
2Reliability
If the height of the post is increased to increase jump distance and prevent dislocation, then dislocation prevention is improved, but amount of bone to be cut increases
Solution Approach 1:
The patent optimizes the geometric parameters of the post including inclination angle of the upper surface and radius of curvature of curved surfaces to achieve adequate jump distance without increasing post height. This allows dislocation prevention while minimizing the amount of bone that needs to be removed during knee replacement surgery, as the effective jump distance is achieved through angular and curvature design rather than height increase.
3Ease of manufacture
If the upper surface of the post is not inclined, then manufacturing is simple, but the thighbone coupling member cannot be restored after dislocation
Solution Approach 1:
The patent designs the upper surface of the post as an inclined surface rather than a horizontal plane, and adds upper and lower curved surfaces with specific radii of curvature. This inclined configuration creates a natural guidance path for the cam during rollback motion, enabling the thighbone coupling member to be restored to its proper position after dislocation while maintaining relatively simple manufacturing processes.
Data Source
AI summary
An artificial knee joint, which includes an upper surface at which a post performs a motion relative to a cam of the thighbone coupling member, is configured such that a radius of curvature of an upper curved surface extending posteriorly from the upper surface is larger than that of a lower curved surface, so as to prevent the cam of the thighbone coupling member from deviating from an inflection point existing between the upper curved surface and the lower curved surface, and is configured such that the upper surface is inclined at a predetermined angle, so as to allow the thighbone coupling member to be restored while naturally descending along the upper surface even when the thighbone coupling member is dislocated, thereby increasing a jump distance without increasing an amount of bone to be cut.