Knee Spacer Implant with Trochlear Trench and Antibiotic Reservoirs
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Solution Overview
Problem
Current spacer implants for temporary knee prosthesis replacement do not adequately ensure joint stability during movement, particularly in the sagittal plane, which can stress the joint and disrupt healing during the recovery period after infection.
Innovation Solution
A spacer implant design featuring a femoral condyle with a longitudinal trochlear trench and a tibial plateau with a keel and stud system for secure bone insertion, along with internal reservoirs for time-controlled antibiotic delivery and metal reinforcements for enhanced stability and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a simple cement block spacer is used, then ease of manufacture is improved, but joint stability during movement deteriorates
Solution Approach 1:
The spacer is divided into multiple functional segments: a femoral component with condyles and a tibial component with plateau, connected by a stabilizing structure. This segmentation allows each part to be optimized for its specific function while maintaining overall joint stability during movement.
Solution Approach 2:
Different regions of the spacer have different structural properties tailored to local requirements. The femoral condyles have specific curvature for articulation, the tibial plateau has a flat surface for load distribution, and the connecting structure provides rotational stability. This local optimization ensures both ease of manufacture and joint stability.
2Ease of operation
If unrestricted knee movement is allowed, then ease of operation is improved, but harmful factors increase due to stress on healing joint
Solution Approach 1:
The spacer incorporates a dynamic stabilizing mechanism that allows controlled movement in safe directions while restricting movements that could harm the healing joint. The structure adapts to the patient's movement needs while providing necessary constraints.
Solution Approach 2:
The spacer acts as an intermediary structure between the femur and tibia, providing a stable platform that mediates joint movement. It allows necessary motion for function while filtering out harmful stress patterns through its specific geometric design.
3Adaptability or versatility
If manual shaping of cement spacer is used, then adaptability to anatomy is improved, but manufacturing precision deteriorates
Solution Approach 1:
The spacer design incorporates pre-formed anatomical features and alignment structures that guide proper positioning and orientation during implantation. The femoral condyles and tibial plateau are pre-shaped to match normal joint anatomy, ensuring both adaptability and precision without requiring manual shaping.
Data Source
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AI summary
The present invention relates to a spacer implant (I) for the temporary replacement of a knee prosthesis, said implant (I) having a femoral condyle (1) and a tibial plateau (2), the lower surface (7) of the femoral condyle (1) resting on the upper surface (8) of the tibial plateau (2), the lower surface (7) of the femoral condyle (1) having a convex shape while the upper surface (8) of the tibial plateau (2) has a concave shape, a pin (9) supported by the tibial plateau (2) and penetrating into a receiving means (17) provided on the femoral condyle (1), the femoral condyle (1) comprising two flanges (12, 13) having different sizes and being joined together via a base (7) through which a groove (17) passes and forms the receiving means, the shorter flange (13) consisting of two elements (15) referred to as condyles, which are spaced apart from one another by the extension of the groove (17), and a stabilizing bar (16) joining the two condyles (15) together at the free end of said flange (13).