Adjustable Graft Fixation Device With Mechanical-Advantage Suture
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Solution Overview
Problem
Existing fixation methods for tissue, particularly in arthroscopic surgery, face challenges in achieving reliable coupling of soft tissue to bone, especially in procedures like ACL repair, due to difficulties in adjusting graft tension and positioning.
Innovation Solution
An adjustable fixation device with a cleat and flexible connector, featuring axial and transverse sliding engagement portions, allows for adjustable tensioning and secure attachment of implantable medical devices like grafts, using a suture with a 4:1 mechanical advantage to minimize elongation and shearing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional fixation methods are used to couple soft tissue to bone, then the surgical procedure can be performed, but the reliability of fixation is insufficient and adjustment of graft tension is difficult
Solution Approach 1:
The fixation device incorporates a dynamic adjustment mechanism that allows the graft tension to be modified after implantation. The flexible connector with sliding engagement portions enables the system to transition from a static to a dynamic state, permitting surgeons to optimize graft tension post-operatively while maintaining secure fixation to bone.
Solution Approach 2:
The device enables change in the tension parameter of the graft after surgical implantation. Through the sliding engagement mechanism, the physical parameter of tension can be adjusted within a specific range, allowing optimization of fixation reliability without requiring revision surgery.
2Adaptability or versatility
If a flexible connector with sliding engagement portions is used, then adjustability of graft tension is improved, but the device complexity increases
Solution Approach 1:
The flexible connector is divided into distinct functional segments: a first portion with intra-connector sliding loop engagement and a second portion with connector-device sliding loop engagement. This segmentation allows each portion to perform its specific function independently, simplifying the overall design while maintaining adjustability.
Solution Approach 2:
The sliding engagement portions provide controlled dynamic movement within defined geometric constraints. The loops slide along predetermined paths, enabling tension adjustment without requiring complex mechanisms or multiple components, thus balancing adaptability with structural simplicity.
3Strength
If the flexible connector is threaded through cleat openings, then secure attachment is achieved, but friction and chafing increase
Solution Approach 1:
The flexible connector is designed as a smooth, continuous loop that distributes contact pressure along its length rather than concentrating stress at single points. This flexible structure reduces chafing on the soft tissue graft while maintaining sufficient friction for secure attachment to the cleat openings.
Solution Approach 2:
The connector features rounded loops and curved engagement surfaces that distribute contact forces more evenly. The curved geometry reduces stress concentration and minimizes chafing on the graft tissue compared to sharp-edged or angular connector designs.
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 device provides improved stability and adjustability, allowing precise tensioning and positioning of grafts, reducing the risk of fixation failure and maintaining joint functionality during healing.
Implementation Method 1
The connector comprises an intra-connector sliding loop engagement portion and a connector-device sliding loop engagement portion. The tensioning end portion of the flexible connector further comprises an axial sliding connector-connector engagement portion and a transverse sliding connector-connector engagement portion
Data Source
AI summary
An adjustable fixation device includes a cleat portion and a suture portion, where the suture portion has a loop portion and a suture tail. Pulling on the suture tail places in tension a graft coupled to the loop portion. The suture is arranged to convey a mechanical advantage so that substantial force can be readily and controllably applied to the graft.