Adjustable Tissue Graft Fixation Loops With Reduced Suture Creep
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Solution Overview
Problem
Current methods for tissue graft fixation, particularly with adjustable suspensory fixation, face challenges such as the need for additional materials like suture tape, potential damage to grafts due to whipstitching, and increased slip or creep of sutures within loops, especially in shorter tunnels, which can compromise surgical precision and safety.
Innovation Solution
Development of fixation devices and methods that utilize detachable bodies, slots, and cradles to secure adjustable suture loops without additional materials, minimize suture slip/creep, and allow for secure attachment to bone blocks, including helical needles for graft stitching and independent adjustable suture systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If whipstitching is used to secure the graft end to the closed loop, then the graft can be secured, but the graft may be compromised and it may be difficult to form on such a small piece of tissue
Solution Approach 1:
The patent removes the need for whipstitching by extracting the graft end securing function from the closed loop design. Instead of stitching the graft to the loop, the loop is configured to engage the graft end directly through friction and geometric interlocking, eliminating the harmful stitching process while maintaining secure attachment
Solution Approach 2:
The patent introduces an intermediary structure - the adjustable fixation device with its specific loop configuration - that mediates between the graft end and the bone tunnel. This intermediary device provides a secure attachment mechanism without requiring direct stitching of the graft tissue itself
2Ease of manufacture
If suture tape or comparable material is used to couple the loop through a hole drilled in the bone block, then the fixation can be completed, but additional materials are required to complete the repair
Solution Approach 1:
The adjustable fixation device is designed as a universal component that performs multiple functions: it provides the closed loop for graft attachment, acts as the bone block interface through its cortical button or engagement features, and eliminates the need for separate suture tape. This multi-functional design reduces the quantity of additional materials required
Solution Approach 2:
The patent merges the functions of the fixation device and the suture coupling system into a single integrated component. The adjustable fixation device incorporates features that directly engage with the bone block and provide the necessary loop structure, combining what were previously separate components into one unified device
3Ease of operation
If adjustable fixation loops are used, then fixation length calculations are minimized and the graft can bottom in the tunnel, but slip or creep of the suture within the loop is more common
Solution Approach 1:
The patent applies local quality by creating specific zones within the loop structure that provide different functions: a smooth section for graft passage, a friction zone for suture engagement, and a locking section for position stabilization. This localized variation in surface properties and geometry prevents slip and creep while maintaining adjustability
Solution Approach 2:
The adjustable fixation device incorporates dynamic elements that allow the loop to adapt its configuration. The device can transition between adjusted states while maintaining stability in the final position, providing both ease of operation during surgery and stability during healing
4Manufacturing precision
If high forces are applied to reduce the adjustable suture loop, then the loop can be reduced to the required size, but the surgeon or surgeon's gloves may be injured or damaged
Solution Approach 1:
The patent replaces the manual mechanical system of pulling and reducing the loop with high forces with a controlled mechanical reduction system. The device incorporates features such as controlled cinching mechanisms or pre-configured loop structures that achieve the required reduction through distributed forces and mechanical advantage, eliminating the need for high-force manual pulling that could injure the surgeon
Data Source
AI summary
Methods and devices for tissue graft fixation include fixation devices attached to an adjustable fixation loop of suture without compromising the graft or requiring additional material to complete the repair. Other fixation devices are attachable to an independent adjustable suture system. Adjustable fixation loops minimize slip/creep of the suture within the loop.