Synthetic Ligament Toggle Anchoring for ACL Reconstruction
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Solution Overview
Problem
Existing synthetic ligament assemblies for ACL reconstruction face challenges such as bone resorption due to small anchoring devices, limited tissue in-growth due to dense structures, and the need for additional tissue harvesting, which can compromise residual hamstring function and increase surgical complexity.
Innovation Solution
A synthetic ligament assembly featuring an elongate woven scaffold with a weftless region forming an internal space for a toggle, allowing for tissue in-growth and secure bone anchoring without additional mechanical bonds, using a toggle with a large bone-facing surface for reduced contact stress and enhanced tissue integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a small EndoButton is used to anchor the ligament, then the bone tunnel diameter can be kept small, but the device exerts large force on the bone causing bone resorption
Solution Approach 1:
The anchoring device transitions from a two-dimensional button pressing against the bone surface to a three-dimensional toggle with a bone-facing surface that distributes load across a larger volume of bone, reducing stress concentration and preventing bone resorption while maintaining small tunnel dimensions
Solution Approach 2:
The invention changes the geometric parameters of the anchoring device by introducing a toggle structure with optimized surface area and dimensional proportions, allowing the same anchoring function to be achieved with reduced contact stress on the bone
2Object-affected harmful factors
If the anchoring device is made larger to reduce contact stress on bone, then bone resorption is reduced, but the device cannot effectively stride the tunnel without requiring a skin incision
Solution Approach 1:
The toggle is designed as a dynamic structure that can be inserted in a compact configuration and then deployed to its functional size within the tunnel, allowing easy insertion without incision while achieving the necessary large bone-facing surface area for stress distribution
Solution Approach 2:
The toggle structure allows the large bone-facing surface to be nested within a compact form factor during insertion, similar to a doll within a doll, enabling the device to pass through the tunnel easily and then expand to its functional configuration for anchoring
3Strength
If a dense structure is used for the ligament assembly, then mechanical strength is improved, but tissue in-growth is limited
Solution Approach 1:
The ligament assembly employs different structural densities in different regions - denser structures where mechanical strength is needed and more porous structures where tissue in-growth is required, optimizing both functions simultaneously through spatial variation of material properties
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 solution reduces bone resorption risk, promotes effective tissue in-growth, and eliminates the need for additional tissue harvesting, providing a more stable and efficient ACL reconstruction method with reduced surgical complexity and improved patient outcomes.
Implementation Method 1
the inner component which is treated to promote the in-growth of tissue following implantation
Implementation Method 2
an elongate woven ligament scaffold which can be located in a tunnel in a bone... the scaffold comprising a plurality of warps extending in a length direction of the scaffold and a plurality of wefts extending transverse to the warps
Implementation Method 3
a toggle having a bone facing surface... securing the scaffold and the inner component in the bone tunnel by contact between the bone facing surface of the toggle and a surface of the bone
Data Source
AI summary
The invention relates to synthetic ligament assemblies for implantation in a body of a patient, such as synthetic ligament assemblies for the reconstruction of the anterior cruciate ligament (ACL). A synthetic ligament assembly (22) comprises an elongate woven ligament scaffold (26) which can be located in a tunnel (18, 20) in a bone (12, 14) wherein the scaffold has an internal space (40) in which an inner component (24) can be placed, which is treated to promote the in-growth of tissue following implantation. The scaffold is folded in a weftless region to form an eye (46) which receives a toggle (28). The scaffold and the inner component are secured in the bone tunnel by contact between the toggle and a surface of the bone.