Flipping-Type Graft Fixation Device Minimizing Flipping Distance
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Solution Overview
Problem
Flipping-type graft fixation devices often result in a significant flipping distance, leading to reduced contact between the graft and bone, which can impede the healing process due to increased graft motion within the tunnel.
Innovation Solution
A graft retention device with an elongated body featuring slidable slots and a tang that allows the graft retention loop to move from one end to a midpoint, minimizing the flipping distance by using a trailing line to reorient the device crosswise within the tunnel, ensuring better bone contact and fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the bar is passed completely outside of the tunnel to initiate flipping, then the bar can be reoriented crosswise, but the suture loop falls back into the tunnel by about 50% of the length of the bar, decreasing graft contact with bone
Solution Approach 1:
The graft retention loop is made slidable along the tang, allowing it to dynamically reposition from a first position near the first end to a second position near the midpoint in response to tension applied during flipping. This dynamic adjustment ensures the loop maintains optimal position within the tunnel throughout the flipping operation, preventing excessive retraction while still allowing complete bar extraction for reorientation.
Solution Approach 2:
The invention changes the positional parameter of the graft retention loop along the tang based on the operational state. When tension is applied to reorient the buckle, the loop's position along the tang changes from the first position to the second position, optimizing the flipping distance and graft contact with bone throughout the procedure.
2Ease of operation
If longer loop lengths are used to accommodate flipping, then the bar can be reoriented, but graft motion within the tunnel increases, potentially slowing healing
Solution Approach 1:
The slidable loop design allows the system to adapt dynamically during flipping. As tension is applied to reorient the buckle, the loop slides along the tang to maintain optimal positioning, thereby minimizing unnecessary graft motion within the tunnel while still enabling complete bar extraction and flipping operation.
Solution Approach 2:
The graft retention loop automatically adjusts its position along the tang in response to tension applied during flipping. This self-adjusting mechanism ensures the loop remains optimally positioned within the tunnel throughout the flipping process, minimizing graft motion and promoting healing without requiring additional control mechanisms.
3Device complexity
If the graft retention loop is fixed at one position, then the structure is simpler, but the flipping distance is increased, reducing graft-bone contact
Solution Approach 1:
The device is segmented into the elongated body with slots defining a tang, and the separable graft retention loop that can slide along the tang. This segmentation allows the loop to independently adjust its position along the tang while the body maintains its structural integrity, achieving both simplicity and positioning precision.
Solution Approach 2:
Rather than a completely fixed loop, the invention provides a loop that can slide along the tang to a predetermined second position near the midpoint. This semi-dynamic approach balances structural simplicity with the ability to optimize graft positioning during flipping, reducing flipping distance while maintaining ease of manufacture.
Data Source
AI summary
A graft retention device has an elongated body with a first and second ends and a midpoint therebetween. A pair of elongated slots formed through the body defines a tang therebetween. A graft retention loop is disposed over the tang and is slidable therealong. A trailing line connects to the body adjacent the slots and extends therefrom through the graft retention loop toward the first end. Tension applied to the trailing line thus tends to urge the graft retention loop away from the first end and toward the midpoint.