Artificial ACL PCL Module for Total Knee Replacement
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Solution Overview
Problem
Current total knee replacement (TKR) prostheses inadequately substitute the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL), leading to reduced functionality and difficulties in physical therapy and limited activity post-surgery, as they often sacrifice the ACL or use incomplete cam and post mechanisms.
Innovation Solution
A prosthetic knee system with artificial ACL and PCL ligaments, comprising a single length of material or discrete components, connected to anatomically correct anchor points on the femoral and tibial components, using synthetic or hybrid materials to replicate the natural ligaments' function and support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the ACL is removed or inadequately substituted with a cam and post mechanism, then the knee replacement can be constructed with simpler components and fewer materials, but the functionality and kinematics of the knee are compromised
Solution Approach 1:
The patent applies the copying principle by creating an artificial ACL that replicates the anatomical structure and function of the natural ligament. The artificial ACL is constructed to mimic the insertion points, orientation, and mechanical behavior of the native ACL, thereby copying its function rather than replacing it with a fundamentally different mechanism like a cam and post.
Solution Approach 2:
The patent replaces the inadequate cam and post mechanical substitution with a more physiologically accurate artificial ligament construct. This substitution uses a continuous cable or strand that dynamically replicates the soft tissue mechanics of the ACL, providing more natural kinematics compared to rigid mechanical components.
2Reliability
If a continuous cable or strand is used to replace both ACL and PCL functions, then the knee kinematics are better preserved, but the device complexity and number of components increase
Solution Approach 1:
The patent merges the ACL and PCL replacement functions into a single continuous cable or strand that passes through both the anterior and posterior aspects of the knee. This unified construct simplifies the overall device by using one component to perform multiple ligament functions, rather than requiring separate artificial ligaments for each function.
Solution Approach 2:
The continuous cable construct exhibits multi-functionality by simultaneously replacing both ACL and PCL functions. The same cable provides anterior and posterior restraint, depending on its routing and attachment points, thereby serving multiple ligamentous functions with a single universal component.
3Ease of manufacture
If the PCL is completely removed and substituted with a post and cam mechanism, then the surgery can be performed with fewer ligament modifications, but the natural knee mechanics are lost
Solution Approach 1:
The patent applies the copying principle to the PCL by creating an artificial structure that replicates the natural ligament's function. The continuous cable is routed to provide posterior restraint similar to the native PCL, copying its mechanical role in controlling knee kinematics during flexion and extension.
Data Source
AI summary
A prosthetic knee with an artificial ACL/PCL. The prosthetic knee includes a femoral component and a tibial component. The artificial ACL/PCL connects the femoral component and the tibial component and includes an anterior cruciate ligament portion connecting an anterior anchor point on the tibial component to a posterior anchor point on the femoral component, and a posterior cruciate ligament portion connecting a posterior anchor point on the tibial component to an anterior anchor point on the femoral component. The artificial ligament may be provided as single length of material and may be pre-assembled into an ACL/PCL module having portions that may be inserted into at least one of the femoral component or the tibial component. A system is also provided for total knee replacement that includes a selection of femoral components, tibial components, and one or more ACL/PCL modules of varying sizes.