Sequentially Anchoring Dual Graft Ligaments in Single Bone Tunnel
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Solution Overview
Problem
Current double-bundle ACL replacement techniques face challenges in accurately anchoring dual graft ligaments within a single bone tunnel, due to limited space and the complexity of replicating the native ACL's mechanical interactions, leading to potential long-term adverse effects.
Innovation Solution
A sequentially-actuated graft anchor system featuring a longitudinal sleeve with radially spaced ligament-contacting surfaces and an asymmetrically offset actuating member, allowing for frictional engagement of each graft ligament with the bone tunnel and sleeve, enabling precise tensioning and anchoring of dual graft ligaments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single bone tunnel is used for dual graft ligaments, then the procedure is simplified and fewer tunnels are required, but the limited space within the single tunnel makes it difficult to accurately anchor both graft ligaments and replicate the native ACL's mechanical interactions
Solution Approach 1:
The single bone tunnel is segmented into multiple engagement zones along its longitudinal axis. The asymmetrically offset profile creates sequentially engaged thresholds at different longitudinal positions, allowing each graft ligament to be anchored at distinct locations within the same tunnel. This segmentation enables precise spatial separation of the two graft ligaments while maintaining a single tunnel structure.
Solution Approach 2:
The invention transitions from a two-dimensional cross-sectional view of the bone tunnel to a three-dimensional longitudinal engagement sequence. The asymmetrically offset profile extends along the longitudinal axis, creating engagement thresholds at different depths within the tunnel. This dimensional approach allows both graft ligaments to be anchored with precision in the limited space of a single tunnel by utilizing the longitudinal dimension.
2Ease of operation
If traditional symmetric anchoring techniques are used in a single tunnel, then the procedure is simpler, but it cannot accurately replicate the native ACL's double-bundle structure and mechanical interactions
Solution Approach 1:
The asymmetrically offset profile introduces asymmetry into the anchoring mechanism, creating engagement thresholds at different longitudinal positions rather than symmetric simultaneous engagement. This asymmetric design allows the first and second graft ligaments to be engaged at different locations and times, accurately replicating the native ACL's double-bundle structure where the anteromedial and posterolateral bundles have different mechanical functions. The asymmetric profile maintains operational simplicity while achieving functional accuracy.
Solution Approach 2:
The asymmetrically offset profile is designed with engagement thresholds positioned at specific longitudinal locations before the anchoring procedure begins. This preliminary configuration of engagement zones allows the surgeon to sequentially engage each graft ligament at its predetermined optimal location, ensuring accurate replication of the native ACL's mechanical interactions without complicating the surgical procedure.
3Productivity
If dual graft ligaments are anchored simultaneously in a single tunnel, then the procedure is faster, but it is difficult to apply appropriate tensioning and anchoring forces to each ligament independently
Solution Approach 1:
The asymmetrically offset profile creates a periodic sequence of engagement thresholds along the longitudinal axis, allowing the actuating member to engage each graft ligament in sequential periods rather than simultaneously. The first engagement threshold is reached before the second, enabling the surgeon to apply tensioning and anchoring forces to each ligament independently in a controlled sequence. This periodic engagement maintains productivity by anchoring both ligaments in a single procedure while ensuring precise control over the tensioning of each individual ligament.
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
This system effectively anchors dual graft ligaments within a single bone tunnel, replicating the native ACL's mechanical interactions, potentially improving long-term knee joint function and reducing complications associated with traditional techniques.
Implementation Method 1
The actuating member is advanced distally into the sleeve inner lumen to cause frictional engagement of the graft ligament with the bone tunnel and the sleeve
Data Source
AI summary
An apparatus for anchoring at least two graft ligaments within a longitudinal bone tunnel includes a longitudinal sleeve having at least two ligament-contacting surfaces located in lateral opposition to a sleeve inner lumen. The sleeve is configured for at least partial insertion into the bone tunnel with each graft ligament positioned laterally adjacent a different ligament-contacting surface and at least partially located between the bone tunnel and the sleeve. An actuating member has proximal and distal actuating member ends. An asymmetrically offset profile is defined by the sleeve and/or the actuating member. The asymmetrically offset profile has engagement thresholds. The actuating member is inserted into the sleeve to cause frictional engagement of each graft ligament with both the bone tunnel and at least one ligament-contacting surface, the frictional engagement of each graft ligament being temporally spaced apart from the frictional engagement of at least one other graft ligament.