Knee Augment Offset Coupler Rotational Stability
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Solution Overview
Problem
In knee arthroplasty and revision surgeries, existing prosthesis kits face challenges in achieving stable fixation of tibia and femoral implants, especially in cases with compromised bone quality and ligamentous attachments, which affects the rotational stability and functionality of the implants.
Innovation Solution
A knee prosthesis kit is designed with cone-shaped members that are secured to the implants, providing additional stability by extending from the implant base and accommodating various bone deformities, along with an offset coupler and wedge components to enhance fixation and rotational stability, using fasteners and a taper lock mechanism for secure attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional prosthesis kits are used, then the basic fixation function is provided, but rotational stability is insufficient in compromised bone conditions
Solution Approach 1:
The prosthesis system is divided into modular components: a base implant, an offset coupler, and an intramedullary rod that can be independently selected and combined. This segmentation allows the surgeon to customize the configuration to match specific bone deformities while maintaining rotational stability through the offset coupling mechanism.
Solution Approach 2:
The offset coupler introduces a spatial offset between the implant axis and the intramedullary rod axis, creating a moment arm that resists rotational forces. This dimensional change from a simple axial connection to an offset connection provides rotational stability without requiring additional complex components.
2Strength
If the prosthesis is designed for high stability, then fixation strength improves, but the device complexity increases
Solution Approach 1:
The intramedullary rod is inserted into and nested within the offset coupler, which itself attaches to the base implant. This nested configuration provides multiple levels of fixation strength while keeping the overall structure compact and the number of discrete components manageable.
Solution Approach 2:
The offset coupler acts as an intermediary component that connects the base implant to the intramedullary rod. This mediator provides the offset geometry needed for rotational stability while simplifying the connection interface between the implant and rod, avoiding the need for complex direct attachment mechanisms.
3Adaptability or versatility
If the prosthesis components are made adaptable for different bone deformities, then versatility improves, but manufacturing precision requirements increase
Solution Approach 1:
The offset coupler is designed with universal features that allow it to work with various base implants and intramedullary rods. Standardized interfaces and the inherent offset geometry provide adaptability to different bone deformities without requiring custom-manufactured components for each case, thereby controlling manufacturing precision requirements.
Data Source
AI summary
A knee prosthesis kit includes an implant and an augment. The implant has a base and a stem extending from the base, and the augment has a base and a conical, cylindrical, or anatomic portion extending from the base. The augment base has at least two openings for receiving fasteners for securing the knee augment to the implant. The portion and the base define a bore for receipt of the implant post. A coupler includes a mating portion for receipt in a bore of an implant post, and a cone-shaped portion extending from the mating portion. A method of providing fixation of knee implants includes securing an augment to an implant and positioning a conical, cylindrical, or anatomic portion of the augment within the intramedullary canal of the tibia or femur.