Total Ankle Prosthesis with Segmented Articular Surfaces
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Solution Overview
Problem
Existing ankle prostheses constrain joint movement, leading to unnatural gait cycles and stress at the bone-component interface due to limited degrees of freedom and uneven weight distribution, resulting in early wear and potential revision requirements.
Innovation Solution
A total ankle prosthesis design featuring talar and tibial components with spheroidal and cylindrical articular surfaces, allowing for area and line contact to distribute weight evenly and provide three degrees of freedom, mimicking natural joint movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If artificial articular surfaces are shaped to facilitate articulation, then movement between joint components is enabled, but weight is concentrated in very small areas causing non-uniform and early wear
Solution Approach 1:
The tibial condyle articular surface is segmented into multiple distinct articular portions (first, second, third articular portions) with different geometric characteristics. The first articular portion has a first curvature, the second has a second curvature, and the third has a third curvature, allowing different regions to contact the talar condyle at different times during the gait cycle, thereby distributing weight across multiple areas rather than concentrating it in a single small contact zone.
Solution Approach 2:
Different portions of the tibial condyle articular surface are given different local geometric properties (curvatures) to match specific functional requirements. The first, second, and third articular portions have different curvatures that correspond to different phases of foot motion, allowing each local region to optimize weight distribution and reduce stress during its active contact period.
2Stability of the object's composition
If articular surfaces are constrained to limit degrees of freedom, then joint stability is improved, but unnatural gait cycle is resulting and stress manifests at bone-component interface
Solution Approach 1:
The articular surfaces are designed with multiple articular portions that dynamically engage with the talar condyle during the gait cycle. As the foot moves through different phases (heel strike, midstance, push-off), different articular portions sequentially contact the talar condyle, allowing the joint to naturally adapt its degrees of freedom to match physiological movement patterns while maintaining stability through continuous articular contact.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 2C~2G
AI summary
A total ankle prosthesis (100) that includes a talar component (110) that has a bone contacting side for contacting a talus and an articular side opposite the bone contacting side. The articular side has first (112a) and second (112b) condyles separated by an intercondylar notch (114). The first condyle defines a spheroidal convex surface (113a). The prosthesis also includes a tibial component (105) that has a bone contacting side for contacting a tibia and an articular side. The articular side has first (132a) and second (132b) condyles separated by an intercondylar spine (134). The first condyle of the tibial component defines a concave surface. The concave surface has a condylar edge (144) that defines a perimeter thereof and a plurality of articular portions positioned between anterior (144a) and posterior (144p)extents of the condylar edge. A first articular portion (140a) of the articular portions is spheroidal and a second articular portion (140b) is defined by a cylindrical helix (132a').