Femoral Component Angled Cement Pockets
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Solution Overview
Problem
During knee replacement surgery, the preloaded bone cement tends to escape from the femoral component as it is positioned on the surgically-prepared distal femur, leading to 'cement ploughing' and additional surgical steps to remove extraneous cement.
Innovation Solution
The femoral component features angled cement pockets on its fixation surfaces, which hydraulically load and contain bone cement, reducing cement ploughing and enhancing cement filling and pressurization for improved bonding to the bone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If bone cement is preloaded on the bone-contacting surfaces of the femoral component, then bonding between the femoral component and the distal femur is improved, but the bone cement tends to escape from the femoral component during positioning, leading to cement ploughing and additional surgical steps
Solution Approach 1:
The fixation surface is segmented into multiple cement pockets distributed across the surface. Each pocket acts as an independent containment chamber for bone cement, preventing uncontrolled escape while maintaining bonding strength through distributed cement placement.
Solution Approach 2:
The cement pockets serve as intermediary structures between the femoral component and the bone cement. These pockets control the interaction between the rigid femoral component and the viscous bone cement, allowing the cement to be contained and pressurized effectively without escaping and causing ploughing.
2Strength
If bone cement is contained and pressurized in cement pockets, then bonding to the bone is enhanced, but the cement must be precisely contained within defined pockets during implantation
Solution Approach 1:
The cement pockets are pre-formed as integral features of the femoral component before implantation. This preliminary structuring of cement containment chambers eliminates the need for precise manual cement placement during surgery, as the pockets are already positioned and sized to contain and pressurize the cement effectively.
Solution Approach 2:
The cement pockets are designed with specific geometric parameters (depth, width, orientation) that optimize cement containment and pressurization. By controlling these parameters, the system achieves enhanced bonding strength while reducing the precision requirements for cement application during implantation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The angled cement pockets effectively contain bone cement, reducing cement ploughing and improving the bonding of the femoral component to the distal femur, thereby simplifying the surgical procedure and enhancing the stability of the implant.
Implementation Method 1
the angled arrangement of the posterior cement pocket hydraulically loads the bone cement within the cement pocket
Implementation Method 2
The angled arrangement of the posterior cement pocket enhances containment of the bone cement
Data Source
AI summary
An implantable orthopaedic knee prosthesis includes a femoral component that is configured to be coupled to a surgically-prepared distal femur. The femoral component has an articular side that includes a posterior femoral condyle surface. A fixation side is opposite the articular side, and it includes a posterior fixation surface that extends generally in the superior/inferior direction. The posterior fixation surface has an angled posterior cement pocket formed therein.