Semi-constrained Ankle Prosthesis Lateral Approach
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Solution Overview
Problem
Existing ankle joint prostheses face high failure rates due to inadequate mobility restoration, poor stability, and complications such as aseptic loosening, deep infections, and damage to neurovascular structures during anterior approach surgeries, which compromise the blood supply to the talus.
Innovation Solution
A lateral approach method for implanting an ankle joint prosthesis using crescentic shaped cuts that follow the natural joint contours, preserving the strongest bone areas and utilizing components with curved surfaces for improved bony ingrowth or cement fixation, along with semi-constrained and mobile bearing designs to enhance stability and motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an anterior approach is used to implant ankle joint prosthesis, then the prosthesis can be implanted, but neurovascular structures providing blood flow to the talus are damaged
Solution Approach 1:
The patent inverts the conventional anterior approach by using a posterior approach for implanting the ankle joint prosthesis. This reversal of the surgical approach allows avoidance of the neurovascular structures that supply blood to the talus, thereby preventing iatrogenic damage while still achieving successful prosthesis implantation.
2Productivity
If traditional ankle joint prostheses are used, then joint replacement is achieved, but aseptic loosening of components occurs frequently
Solution Approach 1:
The patent employs curved and contoured surfaces on the prosthesis components that match the natural anatomy of the talar and tibial surfaces. This curvilinear design increases the surface area for contact and improves the mechanical interlocking between the prosthesis and bone, thereby reducing aseptic loosening and enhancing long-term stability.
Solution Approach 2:
The prosthesis design incorporates different surface characteristics at different locations - with enhanced roughness or porosity at the bone-contacting surfaces to promote bony ingrowth and fixation, while maintaining smooth bearing surfaces for low-friction articulation. This localized differentiation of surface properties addresses both fixation stability and joint function.
3Adaptability or versatility
If planar and curved surfaces are used in intermediate element, then controlled freedom of motion is achieved, but wear of surfaces and stress at interface increase
Solution Approach 1:
The patent introduces a third, mobile bearing component as an intermediary between the talar and tibial components. This intermediate mobile bearing allows controlled freedom of motion while distributing contact stresses across larger surface areas, thereby reducing wear at the articulation interfaces compared to direct contact between fixed surfaces.
Data Source
AI summary
The ankle joint prosthesis adapted to involve the patient's distal tibia and talus has, according to the present invention, tibial, talar and mobile or semi-constrained bearing components that are laterally to medially implanted in the patient. The tibial component's top surface has convex curvature in its anterior to posterior plane and is configured so as to approximate and match with the curvature of a prepared portion of the distal tibia; its bottom surface being approximately flat. The talar component's top surface has saddle-shaped, convex curvature in its anterior to posterior plane, it's bottom surface has concave curvature and is configured so as to approximate and match with the curvature of a prepared portion of the talus. The mobile or semi-constrained bearing components have embodiments that comprise a wide variety of geometric shapes. A method for implanting such a prosthesis is also disclosed.