Toggle Linkage Knee Gap Tensioner for Balanced Ligament Control
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Solution Overview
Problem
Current gap balancing techniques in total knee arthroplasty are complex and difficult to execute, especially when trying to achieve proper balance with the patella in place, as existing devices are large and overly complicated, and not adaptable to different knee systems.
Innovation Solution
A knee gap tensioning apparatus with a tensioner-balancer system comprising a baseplate, top plate, and linkage mechanism that applies a load to the joint gap, allowing for measurement of gap distance, angle, and load, while enabling linear movement of the top plate relative to the baseplate through rotational input, facilitating balanced ligament tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If current gap balancing devices are used, then ligament tension can be applied, but the devices are large, overly complicated, and difficult to operate
Solution Approach 1:
The device is divided into distinct functional modules: a baseplate for attachment to one bone, a top plate for attachment to the other bone, and a linkage mechanism connecting them. This segmentation allows each component to be optimized independently and simplifies the overall structure compared to monolithic gap balancing devices.
Solution Approach 2:
The tensioner-balancer is designed with universal attachment features that can accommodate different knee systems and anatomies. The baseplate and top plate can be attached to various bone surfaces, and the linkage mechanism can accommodate different gap configurations, making the device adaptable to multiple surgical scenarios rather than being limited to a single knee system.
2Device complexity
If current gap balancing devices are used, then ligament tension can be applied, but the devices are large and overly complicated
Solution Approach 1:
The patent extracts only the essential components needed for gap balancing: the baseplate, top plate, and linkage mechanism. Unnecessary features and complex subsystems found in prior art devices are removed, resulting in a lighter, simpler device that maintains full functionality for applying and measuring ligament tension.
3Measurement precision
If current gap balancing techniques are used, then gap measurements can be obtained, but it is difficult to achieve proper balance with the patella in place
Solution Approach 1:
The linkage mechanism acts as an intermediary between the baseplate and top plate, providing a controlled mechanical connection that transmits force while allowing precise measurement of gap changes. This intermediary structure enables accurate measurements to be obtained even when the patella is in place, as the linkage can accommodate the anatomical constraints while maintaining measurement capability.
4Adaptability or versatility
If current gap balancing devices are used, then ligament tension can be applied, but they are not adaptable to different knee systems
Solution Approach 1:
The tensioner-balancer incorporates universal attachment interfaces and adjustable linkage configurations that can accommodate different knee systems and anatomical variations. The baseplate and top plate can be secured to various bone surfaces, and the linkage mechanism can be adjusted to match different gap configurations, making the device versatile across multiple surgical scenarios without increasing complexity.
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
Enables precise and efficient gap balancing during total knee arthroplasty, allowing for patella-in-place procedures and adaptable to various knee anatomies, improving surgical outcomes by ensuring symmetric and balanced flexion and extension gaps.
Implementation Method 1
the linkage is configured so as to produce linear movement of the top plate relative to the base plate, in response to a rotational movement of one or more of the links
Implementation Method 2
a tensioner-balancer operable to apply a load to a gap between the bones of a joint
Data Source
AI summary
A knee gap tensioning apparatus includes: a baseplate, a top plate, and a linkage operable to move the top plate relative to the bottom plate between retracted and extended positions, the linkage including: a first toggle linkage, including a lower link and an upper link; a second toggle linkage, including a lower link and an upper link; a connector linkage interconnecting the first and second toggle linkages; wherein the links comprise parallel pivot axes and the linkage is configured so as to produce linear movement of the top plate relative to the base plate, in response to a rotational movement of one or more of the links; and wherein the linkage includes an input shaft coupled to the linkage and configured to accept a rotary input about an axis parallel to the parallel pivot axes of the links of the linkage.