Constrained Knee Spacer With Hinged Intermediate Component
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Solution Overview
Problem
Current knee joint prostheses face challenges in maintaining joint space and stability, especially during treatment periods for infections or significant bone resection, leading to tissue shortening and muscle atrophy, and existing constrained devices lack adaptability and mobility.
Innovation Solution
A constrained spacer device with pre-formed femoral and tibial components, articulated via an intermediate component and hinges, allowing roto-translational motion, and capable of being impregnated with antibiotics for infection treatment, ensuring stability and mobility while adapting to individual bone conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a constrained device with hinge structure and locking pin is used, then joint stability is improved, but device complexity increases
Solution Approach 1:
The constrained spacer device is divided into distinct modular components: a femoral component with condyles, a tibial component with plateau, and an intermediate component with hinge structure. This segmentation allows each component to perform its specific function while maintaining overall joint stability, reducing the complexity of integrating stability mechanisms into a single monolithic structure.
Solution Approach 2:
An intermediate component serves as a mediator between the femoral and tibial components. This intermediate component contains the hinge structure with locking pins that connect to the tibial component, providing the necessary constraint and stability while simplifying the overall assembly by separating the hinge mechanism from the primary articulating surfaces.
2Length of stationary object
If a rigid constrained device is implanted, then joint space maintenance is improved, but adaptability to individual bone conditions deteriorates
Solution Approach 1:
The device incorporates local quality variations through its modular design, where the femoral component features condyles with specific curvature radii that can be selected to match individual patient anatomy. The tibial component has a plateau surface designed to conform to the distal tibia. This allows the rigid constrained structure to adapt to individual bone conditions while maintaining joint space.
Solution Approach 2:
The hinge structure in the intermediate component provides controlled mobility, allowing the device to adapt dynamically to movement patterns and bone conditions. The hinge allows rotation while maintaining constraint, enabling the rigid device to accommodate individual variations in bone geometry and joint mechanics.
3Reliability
If antibiotic impregnation is added to the spacer device, then infection treatment effectiveness is improved, but manufacturing complexity increases
Solution Approach 1:
The spacer device utilizes porous materials, particularly in the bone cement or polymeric components, which provide high surface area and porosity for effective antibiotic impregnation. The porous structure allows antibiotic agents to be incorporated throughout the material matrix, enabling sustained release and effective infection treatment while maintaining compatibility with standard manufacturing processes for porous biomedical materials.
Data Source
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AI summary
Spacer device (1) for the knee joint comprising a femoral component (2), a tibial component (3) and an intermediate component (30), wherein the femoral component (2) is adapted to be constrained to an end of the femoral bone in proximity to the knee joint, wherein the tibial component (3) is adapted to be constrained to an end of the tibial bone in proximity to the knee joint, the femoral component (2) being adapted to come into contact and to articulate with the tibial component (3), wherein the intermediate component (30) is placed in use between the femoral component (2) and the tibial component (3) and wherein the constrained spacer device (1) comprises a first hinge (32a) and a second hinge (32b) adapted to rotatably constrain the femoral component (2) to the tibial component (3).