Modular Knee Prosthesis Inserts for ACL and PCL Kinematics
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Solution Overview
Problem
Existing total knee replacements (TKR) inadequately substitute the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL), leading to reduced functionality and difficulty in adjusting to physical activity post-surgery due to the lack of anatomically correct replacement.
Innovation Solution
A modular knee joint prosthesis with interchangeable femoral and tibial inserts that mimic the function of both ACL and PCL, allowing for a more anatomically correct simulation of knee kinematics through a system of gears and tracks that guide motion between flexion and extension positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a crude cam and post mechanism is used to substitute the ACL, then the TKR can be constructed with simpler mechanics, but the ACL function is only partially replaced and normal knee kinematics cannot be achieved
Solution Approach 1:
The artificial ligament is segmented into two distinct portions: an ACL portion with a first geometry configured to engage the femoral component, and a PCL portion with a second geometry configured to engage the tibial component. This segmentation allows each portion to be optimized for its specific ligament replacement function while maintaining a unified structure.
Solution Approach 2:
The artificial ligament incorporates dynamic engagement mechanisms where the ACL portion engages and disengages with the femoral component based on knee flexion angle, and the PCL portion similarly engages with the tibial component. This dynamic behavior replicates the natural ligament function that activates only during specific ranges of motion.
2Productivity
If the ACL is removed in most TKR cases, then the surgery can be performed more routinely, but the reconstructed knee has reduced functionality and limited patient mobility
Solution Approach 1:
The artificial ligament structure provides self-regulating functionality where the ACL and PCL portions automatically engage and disengage based on the knee's natural range of motion without requiring external control mechanisms. The geometry of the engagement surfaces ensures proper kinematics are maintained throughout the movement cycle.
3Adaptability or versatility
If a modular design with interchangeable inserts is used, then the prosthesis can be tailored to specific patient anatomy, but the device complexity increases
Solution Approach 1:
The artificial ligament is designed as a universal component that can be used across different TKR configurations. The single structure incorporates both ACL and PCL replacement functionality, and the engagement surfaces are designed to work with standard femoral and tibial components, reducing the need for multiple specialized parts.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
A modular knee joint prosthesis (700) is configured to move between an extended position and a flexion position. The modular knee joint prosthesis includes a femoral component (702) that is configured to be mounted to a femur. The femoral component has a first cutout or opening (712) in a central region thereof for receiving a femoral insert (705). The modular knee joint prosthesis also includes a tibial component (704) that is configured to (i) be mounted either directly or indirectly to a tibia, and (ii) engage the femoral component. The tibial component has a second cutout or opening (723) in a central region thereof for receiving a tibial insert (706). A kit includes the modular knee joint prosthesis, at least two of the femoral inserts having different geometries, and at least two of the tibial inserts having different geometries.