Anatomic Metaphyseal Sleeves for Revision Knee Fixation
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Solution Overview
Problem
Current revision knee arthroplasty components fail to match the anatomical shape and size of the proximal tibia and distal femur, leading to inadequate bone contact, increased stress, intra-operative fractures, and implant malalignment, which compromises long-term fixation and stability.
Innovation Solution
Development of anatomically shaped metaphyseal sleeves and cones that align with the specific anatomy of the proximal tibia and distal femur, utilizing CT scan data and 3D modeling to optimize fit and minimize the risk of fractures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If uniform circular or semi-circular metaphyseal sleeves are used, then device complexity is reduced and ease of manufacture is improved, but the contact area with native bone is insufficient and implant stability deteriorates
Solution Approach 1:
The metaphyseal sleeve is designed with an asymmetric anatomy-based shape that matches the natural contours of the proximal tibia and distal femur, replacing the traditional uniform circular or semi-circular design. This asymmetric geometry optimizes contact with the native bone surface, improving implant stability and fixation while accounting for the non-uniform anatomical structure of the metaphyseal region
Solution Approach 2:
The sleeve incorporates varying wall thicknesses and surface characteristics at different locations to match the specific anatomical requirements of various regions of the metaphysis. This local differentiation allows for optimized bone contact and stress distribution while maintaining manufacturing feasibility through modular construction
2Ease of operation
If non-anatomic devices are forced into anatomic spaces, then ease of operation is improved, but the risk of intra-operative fractures increases
Solution Approach 1:
Instead of forcing the implant to conform to a simplified geometric space, the design inverts the approach by making the implant conform to the actual anatomical space. The anatomy-based shape is prepared to match the natural contours of the bone, allowing the device to fit naturally without requiring excessive bone removal or forcing, thereby reducing intra-operative fracture risk
3Manufacturing precision
If metaphyseal sleeves with uniform shape are used, then device complexity is reduced, but implant alignment precision and fixation durability deteriorate
Solution Approach 1:
The anatomy-based shape is determined through pre-operative CT scanning and 3D modeling, allowing the optimal geometry to be planned before surgery. This preliminary characterization of the patient's specific anatomy enables customization of the sleeve shape to match the unique metaphyseal contours, achieving high precision fit while streamlining the surgical procedure
Data Source
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Figure 3A~3B
AI summary
A prosthetic system is disclosed for providing motion between a first bone and a second bone of a joint. The system can comprise a support structure (e.g., sleeve or a cone, 2420d) having a first end surface (3420), a second end surface (3430), an exterior surface (3440) extending from the first end surface to the second end surface, and an inner surface (3450) defining a passageway (3460) extending from the first end surface to the second end surface, wherein the exterior surface of the support structure is configured to be received in a cavity of the first bone such that the first end surface is flush with or beneath a surface of the first bone. The first end surface is within an axial plane defined by the first end surface and an outermost edge of the first end surface, and a longitudinal axis (LA) of the passageway of the support structure is offset with respect to a geometric center point of the axial plane.